Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 39 num. 5 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Relationship between fatness and puberty in Black Indigenous and SA Landrace gilts</b>]]> In a 2 x 2 factorial design, attainment of puberty in 32 Black Indigenous (BI) and 60 SA Landrace (SAL) gilts was studied under the effects of two treatment diets fed individually ad libitum. Treatment 1 contained 160 g CP and 13.6 MJ DE/kg DM, and Treatment 2, a 25% dilute of Treatment 1 using wood shavings, contained 120 g CP and 10.2 MJ DE/kg DM. Target weights set for BI gilts were from 10 to 50 kg and for SAL, 15 to 120 kg. A sample was slaughtered at each target weight. Reproductive organs were removed, measured and the number, size and physiological state of follicles recorded. Carcasses were deboned and the soft tissue analysed for moisture, protein and fat content. Treatments affected growth significantly. Cumulative mass (lnkg) was regressed against cumulative ME intake (lnME) with b the allometric coefficient in a linear autoregressive model. A change in b indicated a change or breakpoint of physiological development. Puberty was taken to coincide with the breakpoint. Age and weight at puberty differed by treatment for each genotype. Estimated live weight fat (percentage) and carcass fat (percentage) at these ages show a close range between genotypes and treatment diets. <![CDATA[<b>Optimum growth rate of Belgian Blue double-muscled replacement heifers</b>]]> Belgian Blue double-muscled (BBDM) heifers (n = 341) were used to investigate the effect of body weight (BW) at first calving at an age of two years (BWC). Females with a birth weight (BWB) <40 kg realized a lower body weight gain (BWG) up to an age of four months and they also had a significant lower BWC. Dams with a higher BWC gave birth to calves with a higher birth weight. Milk yield during the first four months after calving linearly increased with a significantly higher BWC (R² = 0.34). Females with a daily BWG from zero to four months of age of <0.6 kg have a lower BWC than females with a higher growth rate. A higher rate of gain from zero to four months did not affect subsequent heifer BWG. There was a tendency for a BW-loss during the last trimester of the gestation when BW at conception was lower, especially when this period coincided with the grazing season. This may be due to a reduced intake capacity of BBDM animals and a heavy BWB of the offspring. With mean adult BW of BBDM cows of ca. 710 kg, heifers should gain approximately 0.8 kg/d from birth to conception, to achieve 55 - 60% of their adult BW at the conception at 15 months of age. A lower BWC was only partly compensated from the first up to the third calving, but there was no clear effect on the interval from the first to the third calving. From the present study we can conclude that it is desirable to strive for a pre-partum BW of about 600 kg in BBDM heifers when their first calving occurs at an age of 24 months. Extra attention should be paid to the nutrition of BBDM heifers to realize an accelerated growth rate before they become pregnant. <![CDATA[<b>Influence of dietary lipid sources on sensory characteristics of broiler meat</b>]]> A study was conducted to determine the influence of different dietary lipid sources and inclusion levels on sensory characteristics of chicken breast meat. Eight isoenergetic (15.1 MJ AME/kg DM) and isonitrogenous (223 g CP/kg DM) diets were formulated, using high oleic sunflower oil (HOSO), sunflower oil (SO), fish oil (FO) and tallow (T) at 30 g/kg and 60 g/kg inclusion levels. Eight hundred, day-old Ross 788 broiler males were randomly allocated to the eight treatments (n = 100) and further subdivided into four replicates/treatment (n = 25). All birds receive a commercial starter diet for the first 14 days, where-after the experimental diets were fed for 28 days. At 42 days of age, three birds/replicate (n = 12/treatment) were randomly selected, weighed and slaughtered at a commercial abattoir. Breast muscles were removed from the chilled carcasses (4 ºC) and de-skinned. Meat samples were wrapped in aluminium foil and steamed (200 ºC) before cutting into smaller pieces (2.5 cm³) and served to the respondents (n = 75) of a consumer panel. Each respondent tasted eight meat samples while completing a nine-point hedonic scale questionnaire. Meat samples of the HOSO treatment were preferred, while FO samples were the least acceptable to the respondents. These results suggested that dietary lipid sources could be used to manipulate sensory characteristics of broiler breast meat according to consumer preferences. <![CDATA[<b>The effect of breed type and lactation status on reproductive performance in Awassi ewes</b>]]> This study was conducted to evaluate the effect of breed types and lactation status on reproductive performance of hormonally-treated Awassi ewes. A total of 282 ewes were treated with intravaginal progestagen sponges and equine chorionic gonadotropin. Ewes were mated with fertile rams following sponge removal. Lambing rate was similar between brown-and black-faced ewes, while the percentage of multiple births, fecundity and prolificacy were greater in black-faced ewes. Lambing rate and the percentage of multiple births were similar between lactating and dry ewes. Fecundity tended to be greater in lactating ewes, while prolificacy was similar regardless of lactation status. Results of the present study indicate that black-faced Awassi ewes respond better to hormonal treatment than brown-faced ewes while the lactation status does not appear to influence the ewes' response to hormonal treatment. <![CDATA[<b>Reproductive performance of two sow lines under arid climatic conditions</b>]]> Data (n = 4836) from a pig company in Namibia recorded over the period 2002 - 2007 were analysed to: (i) compare performance of two sow lines for the age at first farrowing (AFF), number born alive (NBA), life total born (LTB), weaning-to-conception interval (WCI), farrowing index (FI) and; (ii) estimate preweaning piglet mortality, non-productive sow days (NPSD) and replacement rates in two sow lines. The mating scheme involved a within herd grandparent programme where line A was the grandparent stock and line C the parent stock. NBA and WCI were analyzed as repeated measures traits. The least square means (d) for AFF were 363.3 ± 3.1 and 353.6 ± 2.4 for A and C, respectively. The NBA increased from first to fifth parity and then declined, but females served during the summer months of October - December (mean monthly temperature = 24.5 ºC) had smaller litter sizes, compared to those in other seasons. Sows weaning piglets in the cold months of May - September (mean monthly temperature = 15.4 ºC) had the shortest WCI. LTB increased by 10.9 ± .1 piglets per unit increase in parity at culling. The FI was 2.4 for both lines. The preweaning piglet mortality was 10.7% for A and 14% for C. The NPSD was 76 d in A and 52 d in C; replacement rate was 50.5% in A and 42.1% in C. Component traits of reproduction indicate depressed performance during the summer period. Management efforts should be directed at further mitigation of heat stress in breeding pigs and reduction of preweaning piglet mortality in line C. <![CDATA[<b>Relationships between cock semen viability and the fertility of artificially inseminated South African indigenous chicken breeds</b>]]> One hundred and sixty hens and 32 cocks of four different South African indigenous chicken breeds (Naked Neck (NN), Ovambo (OVB), Potchefstroom Koekoek (PK) and Venda (VD) were used in this study. Reproductive performance tests as determined by the number of ejaculations per five minutes of abdominal sexual massage (5ASM) were used to select 16 high performing (HP) and 16 low performing (LP) cocks from a population of 80 cocks. Cocks with >2 ejaculates/60 min or <1 ejaculate/60 min following ASM were considered as HP or LP cocks, respectively. Semen was collected from each cock following 5ASM, evaluated for semen viability and 0.05 mL diluted semen used to inseminate five hens per breed, in each experimental group. Significant differences in ejaculation rates and semen quality and quantity were recorded in the four breeds of cocks - with the HP cocks of the PK breed producing the highest ejaculation rate (4.1 ± 0.1/60 min), ejaculate volume (0.7 ± 0.02 mL), sperm motility (92 Class Test 2 ± 0.7), percentage live sperm (88.4 ± 0.7%) and total sperm per ejaculate. Significant differences were also recorded in hen fertility and subsequent hatchability of set eggs. Semen from the HP cocks were superior to those from the LP cocks, as evidenced in most of the fertility and hatchability parameters, with PK layers producing eggs that gave the highest average egg weight (58.04 ± 0.9 g), fertility (74.3 ± 0.2%), hatchability of set eggs (84.03 ± 0.7%), percentage of normal chicks (98.1 ± 0.7%) and chick weight (37.9 ± 0.3 g). Results suggest that selection of high performing cocks following five minutes of sexual massage prior to semen collection enhances semen quality and quantity leading to significant improvement in the fertility of artificially inseminated hens. <![CDATA[<b>Effect of saponified high fat sunflower oilcake and lipoic acid on fat quality of lambs</b>]]> Sheep fat contains relatively high levels of saturated fatty acids while poly-unsaturated fatty acids (PUFA) are toxic to cellulolytic bacteria and are also saturated in the rumen. Stabilization of residual oil in sunflower oilcake by conversion into calcium salts would be advantageous. Alpha lipoic acid acts as an anti-oxidant to ameliorate the effects of oxidative stress caused by high dietary levels of PUFA. Residual oil (14%) in mechanically extracted (expeller) sunflower oilcake (SFOC) was saponified in situ and compared in a complete feedlot diet (100 g crude protein and 31 g extractable fat/kg feed) with commercially extracted oilcake containing 2.4% residual oil (control diet with 29 g fat and 123 g crude protein kg feed) fed to four groups of 10 SA Mutton Merino weaner lambs (ca. 23 kg) for nine weeks. Both diets were fed either with, or without a weekly oral dosing of 500 mg α-lipoic acid. Fatty acid composition was determined on back fat samples while thiobarbituric acid-reactive substances (TBARS) were determined on samples of m. longissimus dorsi stored for zero and six months and displayed for six days. The back fat of the lambs on the saponified expeller SFOC diets contained significantly higher levels of saturated fatty acids and lower levels of mono-unsaturated fatty acids. PUFA were unaffected. High TBARS levels (>1.0) were found after six months storage. Non significant increases in TBARS were observed in the groups that received lipoic acid. <![CDATA[<b>Diet selection by Nguni goats in the Zululand Thornveld</b>]]> The aim was to determine diet selection of goats grazing/browsing in Zululand Thornveld. An experiment was done in spring (November 2007) and autumn (March/April 2008) at Owen Sitole College of Agriculture, KwaZulu-Natal. Diet selection was estimated using direct observation of animals and an indirect plant-based method. The browse species observed in the plant-based methods were: Gymnosporia senegalensis (Gs), Acacia nilotica (An), Acacia karroo (Ak), Scutia myrtina (Sm) and Dichrostachys cinerea (Dc). Selection was determined by observing at regular intervals 40 marked branches on 10 plants of each browse species. Direct observation of diet selection was done by observing two goats in a base herd of 24 castrated males when they were allowed to forage together in a paddock of 1 ha. Observations were made every minute for three hours in the morning and 1.5 hours in the afternoon. The relative abundance of the browse species in the veld was determined and used to estimate the selection index (utilization relative to availability). In both seasons, the three most selected species according to the plant-based observations were Sm, Ak and Dc. Consistently, An experienced moderate defoliation and Gs the least. However, on the basis of the selection index the species followed the order: An>Dc>Ak>Sm>Gs in spring and An>Sm>Dc>Ak>Gs in autumn. The selection index was negatively correlated to all fibre attributes although the correlation attained significance only for NDF, ADF and lignin but not for tannins and cellulose. Both methods did not rank species in the same order, thus suggesting the need for further methodological refinement. <![CDATA[<b>Effect of limestone particle size on egg production and eggshell quality of hens during late production</b>]]> A study was conducted to determine the influence of different particle size limestone in layer diets on egg production and eggshell quality during the later stages of egg production (>54 weeks of age). Calcitic limestone (360 g Ca/kg), consisting of small (<1.0 mm), medium (1.0 - 2.0 mm) and large (2.0 - 3.8 mm) particles were obtained from a specific South African source that is extensively used in poultry diets Isoenergetic (14.32 MJ AME/kg DM) and isonitrogenous (172.01 g CP/kg DM) diets with a dietary Ca content of 39.95 g Ca/kg DM were used. Sixty nine, individual caged Lohmann-Silver pullets, 17 weeks of age, were randomly allocated to the three treatments (n = 23) for the determination of various egg production and eggshell quality characteristics. Egg production and eggshell quality data recorded on individual basis at 54, 58, 64 and 70 weeks of age were pooled to calculate and statistical analysed parameter means for the late production period. Different limestone particle sizes had no effect on any of the tested egg production and eggshell quality parameters. These results suggested that larger particles limestone are not necessarily essential to provide sufficient Ca2+ to laying hens for egg production and eggshell quality at end-of-lay, provided that the dietary Ca content satisfies the requirements of the laying hen. <![CDATA[<b>Effect of limestone particle size on bone quality characteristics of hens at end-of-lay</b>]]> A study was conducted to determine the effect of different limestone particle sizes in layer diets on bone quality characteristics at end-of-lay hens. Calcitic limestone (360 g Ca/kg DM) that is extensively used in commercial poultry diets was obtained from a specific South African source. Limestone particles were graded as small (<1.0 mm), medium (1.0 - 2.0 mm) and large (2.0 - 3.8 mm) and included (94.4 g/kg) into isoenergetic (14.3 MJ AME/kg DM) and isonitrogenous (172 g CP/kg DM) layer diets. Sixty-nine, individual caged Lohmann-Silver pullets, 17 weeks of age, were randomly allocated to the three treatments (n = 23) for the determination of various bone dimensional and mechanical properties at end-of-lay. At 70 weeks of age, 10 birds per treatment (n = 10) were randomly selected and sacrificed for the removal of tibia and humerus bones. Different limestone particle sizes had no effect on bone weight, length or diameter at 70 weeks of age. However, an increase in limestone particle size resulted in a significant increase in tibia breaking strength and -stress. These results suggested that larger particles limestone (>1.0 mm) have a beneficial effect on improving the mechanical properties of bone of older laying hens. <![CDATA[<b>Effect of dietary lipid sources on production performance of broilers</b>]]> A study was conducted to determine the influence of different dietary lipid sources and inclusion levels on production performance of male broilers. Eight isoenergetic (15.1 MJ AME/kg DM) and isonitrogenous (223 g CP/kg DM) diets were formulated, using high oleic sunflower oil (HO), sunflower oil (SO), fish oil (FO) and tallow (T) at a 30 g/kg and 60 g/kg dietary inclusion level. Eight hundred (800), day-old Ross 788 broiler males were randomly allocated to the eight treatments (n = 100) and were further subdivided into four replicates/treatment (n = 25). All birds receive a standard commercial diet for the first 14 days, where-after the experimental diets were fed for 28 days. Feed intake and body weights were recorded weekly, while mortalities were recorded and dead birds weighed daily. Mortalities were brought into consideration during the calculation of average daily feed intake (g feed/bird/day) and feed conversion ratio (g feed/g body weight gain). Contrary to saturated fatty acids (T), the inclusion of unsaturated fatty acids (HO, SO, FO) at a higher level (60 g/kg) resulted in a significantly improved FCR. It seems that the optimum dietary inclusion level of saturated fatty acids is lower (30 g/kg) than that of unsaturated sources. <![CDATA[<b>Influence of dietary lipid sources on carcass traits of broilers</b>]]> A study was conducted to determine the influence of different dietary lipid sources on dressing percentage, breast meat yield and breast weight of male broiler birds. Four isoenergetic (15.1 MJ AME/kg DM) and isonitrogenous (222.3 g CP/kg DM) diets were formulated, using high oleic sunflower oil (HO), sunflower oil (SO), fish oil (FO) and tallow (T) at a 60 g/kg dietary inclusion level. Four hundred, day-old Ross 788 broiler males were randomly allocated to the four treatments (n = 100) and further subdivided into four replicates/treatment (n = 25). All birds receive a standard commercial diet for the first 14 days, where-after the experimental diets were fed for another 28 days. At 42 days of age, three birds/replicate (n = 12/treatment) were randomly selected, weighed and slaughtered at a commercial abattoir. Chilled carcasses (4 ºC) were weighed to determine dressing percentage. Breast muscles were removed from the chilled carcasses, skinned and weighed for the calculation of breast meat yield. Breast meat yield were expressed as a percentage of the live body weight as well as carcass weight. This study showed that the broilers fed a diet supplemented with 60 g/kg tallow had a better dressing percentage, breast meat yield and breast weight compared to other treatments. These results suggested that dietary lipid sources could be used to improve certain carcass traits of broilers. <![CDATA[<b>Feed utilization and growth of Dorper wethers on <i>Opuntia</i>-based diets</b>]]> Incremental levels of sun-dried and coarsely ground cactus pear (Opuntia ficus-indica var. Algerian) cladodes were used to substitute part of the lucerne hay in balanced diets fed to Dorper wethers (n = 28; 33.90 ± 2.98 kg) during a trial period of 63 days. The three treatment diets (T0, T24 and T36) comprised respectively (air dry basis) 0, 240 and 360 g/kg Opuntia; 660, 410 and 285 g/kg lucerne hay; 300 g/kg maize meal; 0, 10 and 15 g/kg feed grade urea; and 40 g/kg molasses meal. Apparent DM digestibility coefficients increased significantly (0.714, 0.732, and 0.756) with Opuntia inclusion in diets. Feed dry matter (DM) intake (1.368, 1.345 and 1.317 kg DM/day) and average daily gain (117.8, 116.4 and 95.6 g/day) decreased slightly as Opuntia inclusion increased. Similar to previous studies the ingestion of Opuntia caused the production of wet faeces by the wethers. It was concluded that adequate nutrients were provided by these diets for maintenance and a moderate level of production in the Dorper wethers. <![CDATA[<b>Simplification of urea treatment method of wheat straw for its better adoption by the farmers</b>]]> Limited use of cereal straws in livestock feeding is due to their low voluntary intake, low protein contents and low digestibility. Nutritional value of these roughages can be improved through chemical or physical methods. Efficacy of treating straw with urea for improving its nutritive value is considered equivalent to anhydrous or aqueous ammonia. However, the adoption rate of urea treatment by farmers is low, maybe due to relatively tedious technology and higher requirement of labour. There is need to simplify urea treatment methods. In the present study an effort has been made to simplify the existing urea treatment method so that farmers could easily adopt this technique. The new method involves weighing the required amount of urea (4% of straw), mixing it with double the amount of farm manure (as urease source), giving 30% moisture by adding water, putting this mixture in a bag, piling the straw on the bag, again moistening the straw with water (50% of straw) and incubating this material for a month under the cover of plastic sheet or mud plaster. In this method three steps including preparation of urea solution, sprinkling of solution on straw and pressing the straw during treatment process, have been eliminated which resulted in saving labour by 55%. The efficiency of the new method, however, is about 30% less than the conventional urea treatment method. <![CDATA[<b>Effect of All-lac xcl 5x, Acid-pak 2x, Bio-mos® and Zinc Bacitracin on nutrient digestibility and gastrointestinal morphology of broiler chickens</b>]]> An experiment was conducted with Ross broiler chickens from day-old to 42 d of age. A prebiotic (Bio-Mos®), probiotic (All Lac XCL 5x), organic acid (Acid pak 2x), individually or in combination were used to supplement an antibiotic growth promoter (Zinc Bacitracin). The chickens were challenge with Clostridium perfringens (CP) at 21, 22 and 23 days of age to determine the efficacy of these additives for replacing antibiotics in hindering the effects of CP on the villus surface area. Feed additives in this experiment prevented the negative effects of CP as the treated birds did not have lesions on their villus surfaces. <![CDATA[<b>Growth, haematological and biochemical responses of growing lambs injected with growth hormone and supplemented with calcium soaps of fatty acids</b>]]> Physiological and productive responses to recombinant bovine somatotropin (rbST) injection and calcium soap of fatty acids (CSFA) supplementation were studied in post-weaning male Rahmani lambs. Male lambs (n = 20) of similar initial body weight (27.9 kg) and age (162 d) were divided randomly into four equal groups. The first was fed the injected with 100 mg of rbST biweekly; the third (basal diet and served as control; the second (GH) was CSFA) was supplemented with 50 g/d of CSFA and the fourth (GH + CSFA) was injected with 100 mg of rbST biweekly plus 50 g/d of CSFA. Treatments increased the average daily gain and final body weight. Concentration of insulin-like growth factor-1 (IGF-1) in lambs treated with (GH) and (GH + CSFA) was higher than that of CSFA and control groups. Haematological parameters (RBC, WBC, and haemoglobin concentrations) did not change. Animals injected with rbST had higher serum total protein than other treated groups and controls. Control lambs showed the least serum albumin concentration. Injection of rbST and supplementation of CSFA increased serum glucose in treated lambs compared to controls. Serum urea concentration was not affected by injection of GH, while CSFA supplementation decreased serum urea concentration compared to the control. Serum triglycerides concentration decreased in rbST-injected lambs than other treatment groups. Lambs supplemented with CSFA only or combined with rbST had higher concentration of serum cholesterol than control or rbST-injected lambs. The results of the present study suggest that rbST and CSFA may increase the average daily gain and improve the physiological status of growing lambs. <![CDATA[<b>Determining the optimum temperature for dry extrusion of full-fat soyabeans</b>]]> Full-fat soyabeans (FFSB) intended for use in monogastric nutrition need to undergo heat treatment so that present anti-nutritional factors can be inactivated. Under- or over-treatment will decrease the level of amino acids available to the animal. In this study, the slope-ratio technique was used in two trials with broilers for determining the optimum treatment temperature for soyabeans. Average daily weight gain (ADWG) and feed conversion efficiency (FCE) were used as response parameters. The optimum temperature for dry extrusion of FFSB was 144 ºC for Trial 1 and 138 ºC for Trial 2. Similar temperature values were generated by both ADWG and FCE. Either one can therefore be used as response parameter for determining the optimal heat treatment conditions of FFSB for use in poultry feeding. <![CDATA[<b>Sample preparation of <i>Medicago sativa</i> L. hay for chemical analysis</b>]]> The objective of this study was to quantify the effect of the grinding procedure on the moisture and crude protein concentration of a ground Medicago sativa L. hay sample for quality grading. An additional aim was to investigate the accuracy of electronic moisture testers (EMT). Variance of analyses revealed significant differences in moisture concentration between ground (CV = 16.1%) and unground (CV = 27.4%) samples ranging from 14.7 up to 41.1% of the unground sample. The grinding process had a non-significant influence on the CP concentration of the final grounded product. EMT failed to accurately predict moisture concentration around the moisture area of critical concern (16% and higher) where heat and/or mould damage are likely to occur. It was concluded that analytical moisture standards for Medicago sativa L. hay should be based on the original moisture concentration of samples in the unground state to be relevant for quality grading. <![CDATA[<b>A Bayesian approach to the Japanese Black cattle carcass genetic evaluation</b>]]> Volumes of the routine carcass field data used in the official genetic evaluation for carcass traits in Japanese Black cattle are increasing rapidly. The purposes of this paper are to describe a Bayesian approach via Gibbs sampling (GS) to be used in the Japanese Black carcass genetic evaluation, and in particular using a very large carcass field data, to compare breeding values for sires and dams of animals with records estimated using GS and the conventional empirical best linear unbiased prediction (EBLUP) employing the restricted maximum likelihood (REML) estimates of variance components. The total of six carcass traits evaluated were carcass weight, rib eye area, rib thickness, subcutaneous fat thickness, estimated muscle yield percentage and marbling score. As prior distributions for GS, uniform, normal and independently scaled inverted chi-square distributions with degree of belief and scale parameters of -2 and 0 were used for nuisance parameters, breeding values and variance components, respectively. The posterior means were calculated using every 10th sample from a total of 90 000 samples, after 10 000 samples had been discarded. Moment and rank correlations between breeding values estimated by the GS and the REML-EBLUP were all very close to one, and the coefficients and the intercepts for linear regression of the GS on the REML-EBLUP estimates were substantially one and zero, respectively, showing a very good agreement between breeding value estimation by the GS and the REML-EBLUP. <![CDATA[<b>Growth and slaughter characteristics of Ankole cattle and its Boran and Friesian crossbreds</b>]]> One hundred and forty four bulls comprising 48 animals of each breed, i.e. purebred Ankole (ANK) and its crossbreds with Boran (AXB) and Friesian (AXF) were assigned to three feeding systems (FS) to evaluate their performance for improved beef production. The bulls, averaging 191 ± 9.6 kg live weight and 18 months of age, were arranged in a completely randomized design in a 3 X 3 factorial treatment arrangement. The feeding systems comprised: T1 (Grazing alone), T2 (Grazing + concentrate) and T3 (feedlot finishing with maize stover plus 60% concentrate fed ad libitum). Both genotype and feeding system affected growth and slaughter characteristics. The AXF crossbreds had higher average daily gain (ADG) (620 g/day) than ANK (560 g/day) and AXB (500 g/day). Average daily gain was higher in T3 (850 g/day) than in T2 (550 g/day) and T1 (270 g/day). Hot carcass weight and dressing percentage varied in a descending order of 145, 132, 110 kg and 52, 51 and 50% for T3, T2 and T1, respectively. Similar trends were observed for non-carcass components although there were no differences between T3 and T2. Except for external non-carcass components, genotype did not affect slaughter characteristics. The results of this study indicated that the indigenous Ankole cattle have a great potential for beef production when finished in a feedlot even without crossbreeding. <![CDATA[<b>Prospects of performing multiple-country comparison of dairy sires for countries not participating in Interbull international genetic evaluations</b>]]> International trade with genetic material has lead to the foundation of Interbull, an international organization that performs international evaluations of dairy bulls, enabling countries to obtain breeding values of foreign bulls on their on scale. Not all countries have the possibility to participate in the evaluations with their own national breeding values. The aim of this study was to find an alternative method that does not require national breeding values. Argentina was used as a representative of countries without national breeding values. For this study national breeding values for 909 Argentinean bulls were available; these records were used in a normal Interbull international evaluation and used as reference. The alternative method considers Argentinean bulls as unrecorded, but correlated to bulls in other countries. This method was used with seven different correlation matrices, giving seven alternatives to compare with the reference. Results showed correlation between reference and the alternative methods ranging between 0.926 and 0.973, and loss in genetic gain between 2.82% and 11.9%. This means that this alternative method could be used for countries that do not have national breeding values to submit for international evaluations. <![CDATA[<b>Genetic relationships between calving interval and linear type traits in South African Holstein and Jersey cattle</b>]]> Genetic correlations between first calving interval (CI) and linear type traits in South African Holstein and Jersey cattle were estimated to assess the possibility of using type information as selection criteria for CI. All linear type traits routinely evaluated under the National Genetic Evaluation Programme (18 for Jersey and 17 for Holstein) were considered. Data were obtained from the National Dairy Animal Recording Scheme and comprised records of 30 503 Holstein cows in 640 herds and 27 360 Jersey cows in 460 herds. Multiple-trait animal models were used to estimate parameters, based on the restricted maximum likelihood (REML) methodology. Fixed effects in the model varied depending on the individual trait. Linear type traits reflecting body size generally had much higher correlations with CI than udder characteristics. Genetic correlations of CI with body size traits were mostly positive in both breeds, ranging from 0.04 ± 0.16 with bone structure to 0.51 ± 0.08 with body depth, dairy strength and rear leg set. Correlations between CI and body depth (0.51 ± 0.08), angularity (0.32 ± 0.08) and rump angle (0.32 ± 0.12) indicate that cows with deep, more angular bodies and low pins have longer CI. Genetic correlations with udder type traits were generally low, ranging from -0.01 ± 0.20 with udder width to 0.25 ± 0.11 with rear teat placement. The highest genetic correlations with CI were for rear leg rear view (-0.70 ± 0.34), body depth (0.51 ± 0.08), dairy strength (0.51 ± 0.09), rear leg set (0.51 ± 0.06), foot angle (-0.44 ± 0.04) and rump angle (0.32 ± 0.05) in the Jersey and rump height (0.31 ± 0.08), angularity (0.32 ± 0.08) and body depth in the Holstein (0.51 ± 0.08). These traits may therefore be used in the analysis of CI to carry out early prediction of fertility and increase the accuracy of evaluation. <![CDATA[<b>Characterization of sheep populations of Kenya using microsatellite markers</b>: <b>implications for conservation and management of indigenous sheep populations</b>]]> Indigenous sheep of Kenya are very important to resource-poor farmers and pastoralists. They have over time adapted to the harsh environmental conditions of the arid and semi-arid lands where they are faced with challenges of persistent droughts, diseases, conflicts and poor nutrition, yet show resistance to gastrointestinal nematodes. In recent years, these indigenous sheep populations have been crossbred indiscriminately to exotic breeds particularly the Dorper. A study was undertaken to determine the level of genetic diversity and relatedness between the various sheep populations and breeds of Kenya. This paper reports results on the genetic diversity and admixture observed using microsatellite DNA markers. <![CDATA[<b>Association of the polymorphism in the 5' flanking region of the ovine IGF-I gene with growth traits in the Baluchi sheep</b>]]> The insulin-like growth factor 1 (IGF-I) gene has been described in several studies as a candidate gene for growth traits in farm animals. The present preliminary study attempts to establish associations between growth traits and genetic polymorphisms at the 5' flanking region s IGF-I in the Baluchi sheep. The DNA of 102 sheep of the indigenous Iranian Baluchi breed was evaluated. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis of the 5' flanking region (Exon1) of the ovine IGF-I gene revealed three banding patterns (genotypes) named as A/A, A/B and B/B. The evaluation of an association effect between these SSCP patterns with birth weight (BW), weaning weight (WW), and average daily gain from birth to weaning (GBW), weaning to six month (GWS) and from six month to yearling age (GSY) suggest a positive effect of pattern (Genotype) A/B with GBW and weaning weight (WW). Pattern (Genotype) B/B had a superior birth weight when compared to those of individuals with other patterns. Moreover, the A/A pattern (Genotype) appeared favourable for live weight at yearling age. These results confirmed the potential usefulness of this gene in marker-assisted selection programmes for sheep breeding. <![CDATA[<b>Non-genetic and genetic factors influencing growth performance in Murrah Buffalos</b>]]> Live weight data from 590 Murrah buffalo calves (140 male and 450 female calves) maintained at the Central Cattle Breeding Farm, Alamadhi, Tamil Nadu, India, born in the period between 1990 and 2004 were used for this study. Data were analysed using least-squares procedures. The adjusted birth weights of male and female calves were 33.0 ± 0.49 and 31.9 ± 0.27 kg, respectively, with an overall value of 32.4 ± 0.30 kg. The mean body weight at three, six, nine and 12 months of age pooled over periods, season and sex were 62.0 ± 0.65, 87.9 ± 0.95, 112.4 ± 1.23 and 134.16 ± 1.41 kg, respectively. Period of calving influenced the weight significantly at birth, three and six months of ages only. The effect of dam parity on body weight at different ages was highly significant. The calves born during the dam's second parity were generally heavier than those born in other parities. Generally, males had a higher body weight than females at all age groups. All the growth traits showed medium heritability (direct) estimates, which ranged between 0.12 ± 0.01 and 0.22 ± 0.16. The genetic correlations were all medium to high and positive. The genetic parameter estimates indicated that the six months weight can be used as a selection tool for genetic improvement of growth traits considering its high heritability and positive genetic correlations with succeeding growth traits. <![CDATA[<b>Genetic and non-genetic factors affecting body weight in Tellicherry goats</b>]]> Data on 566 Tellicherry goats, recorded between 1988 and 2007 were used to study the effect of non-genetic factors on body weight and daily gain from birth to 12 months of age. The least-squares means for body weight at birth and at 12 months of age were 2.17 ± 0.03 and 18.78 ± 0.44 kg, respectively. The pre- and post-weaning average daily weight gains were 72.41 ± 1.68 and 37.46 ± 1.49 g, respectively, and the associated growth efficiencies were 3.11 ± 0.08 and 1.34 ± 0.05, respectively. Significant differences associated with the year of kidding were observed in body weight, weight gain and efficiency in weight gain at different stages of growth. Growth rate of kids born between December and February was relatively slower than those born in other months and this can result from seasonal changes and suggests that it is necessary to plan the kidding season rationally by controlling the oestrus and mating time. The kids born as twin had lower birth weight and slower early growth rate than those born as single but had a higher post-weaning growth rate. The heritabilities of different traits were moderate to high, except for birth weight, which was of low heritability. The phenotypic and genetic correlations among the different body weights were positive and low to high in magnitude. <![CDATA[<b>Economic values for dairy production traits under different milk payment systems in South Africa</b>]]> Economic values of milk volume (VOL), fat yield (FYLD), protein yield (PYLD), live weight (LWT), longevity (LON), calving interval (CIV) and somatic cell score (SCS) were derived for Holstein and Jersey cattle, based on milk payment systems of four major milk buyers in South Africa. The economic value of somatic cell score was calculated for only two of the payment systems. A bio-economic model was used to calculate economic values by determining changes in profit arising from an independent unit increase in each trait. Economic values for VOL, FYLD and PYLD varied substantially among the payment systems; particularly PYLD which ranged from ZAR 7.62/kg to ZAR 21.88/kg. Payment systems that do not pay for milk volume resulted in a negative economic value (-ZAR 0.49/l) for VOL. Live weight and CIV had constant economic values across payment systems (-ZAR 6.62/kg and -ZAR 5.75/day for Holstein and -ZAR 7.49/kg and -ZAR 4.19/day for Jersey, respectively, for LWT and CIV). Economic value of LON varied slightly with payment system (ZAR 1.09/day to ZAR 1.23/day in the Jersey and ZAR 3.59/day to ZAR 3.68/day in the Holstein). The economic value of SCS differed substantially between the two payment systems and was higher in the Holstein (-ZAR 949.26/score and -ZAR 1795.57/score) than in the Jersey (-ZAR 433.87/score and -ZAR 912.90/score). Relative emphasis of traits in the breeding objectives for South African dairy cattle should take due cognisance of the diversity in milk payment systems. <![CDATA[<b>A systems approach to the south african dairy industry</b>]]> Milk production in South Africa comes under pressure periodically as a result of market forces, but can dairy producers effectively respond to these market forces? During these periods a large number of dairy cows are slaughtered and their numbers decrease. As the average productive life of dairy cows is 2.3 lactations, their numbers cannot be increased easily if market forces change. This paper demonstrates that the national dairy herd can only increase by 1 - 3% per life cycle through normal population growth. Short-term financial issues influencing the milk price or input costs can thus have a drastic and long-term effect on the population dynamics of the national herd. The low surplus numbers imply that selection pressure from the female side is almost non-existent. This raises the question as to whether South Africa breeds of dairy cattle are adapted to local conditions especially as large quantities of semen are imported. The low participation of only 24% in official milk recording is of concern as the performance of cows in milk recording is substantially better, viz. the difference between cows in milk recording and those that are not, as far as the productive herd life is concerned, is an improvement of 43%, and in milk production 81%. World-wide agricultural production is increasingly practiced in a systems relationship. The South African dairy industry must realize how interdependent they are and begins to think in terms of a systems approach. <![CDATA[<b>A comparative study on growth performance of crossbred and purebred Mecheri sheep raised under dry land farming conditions</b>]]> In order to improve mutton production, Dorset x Mandya and Dorset x Nellore halfbred rams were mated with Mecheri ewes to produce Dorset x Mecheri x Mandya and Dorset x Mecheri x Nellore quarterbreds. Least-squares analyses of the body weight of crossbred (n = 541) and purebred (n = 959) Mecheri sheep were made. The overall means for bodyweight of crossbred Mecheri sheep at birth, three, six, nine and 12 months of age were 2.27 ± 0.05, 7.97 ± 0.24, 11.84 ± 0.38, 14.73 ± 0.48 and 17.55 ± 0.56 kg, respectively and for purebred Mecheri sheep the values were 2.27 ± 0.02, 7.80 ± 0.10, 11.48 ± 0.15, 14.04 ± 0.17 and 16.23 ± 0.18 kg, respectively. Crossbreds had higher body weight than purebred Mecheri sheep at all age groups. However, it was not significant up to nine months of age. In general, period of lambing and sex of the lambs had significant effects on body weight of both genetic groups at different ages. The estimates of heritability for body weight ranged from 0.177 ± 0.129 to 0.338 ± 0.176 among different age groups. Highest heritability estimates were obtained for body weight at three and six months of age, hence these traits may be considered as selection criteria for improving the body weight of Mecheri sheep at different age groups. <![CDATA[<b>A comparison between hominy chop and defatted maize germ meal as the main energy source in diets of feedlot steers</b>]]> Defatted maize germ meal (DMG) is arbitrarily rated at a lower economic value than maize meal or hominy chop (HC). Five treatments with 15 steers each were fed different inclusion levels of DMG (0%, 25%, 50%, 75% and 100%), replacing hominy chop during the fattening period. Slaughter data were collected for carcass performance evaluation. DMG has lower fat levels and higher NDF (fibre) levels than HC. A slightly higher feed intake (8.1% for T5 vs. T1) and lower gain (-4.4% for T5 vs. T1) of steers on DMG containing diets resulted in a 9 to 14% poorer feed conversion ratio in comparison to steers on the HC diet. No differences were observed between carcass weights for all treatments and dressing percentage did not differ between T1 (57.4%) and T5 (57.8%). Pricing levels need to be adjusted to reflect the nutritional value of DMG. <![CDATA[<b>Herbage yield in Signalgrass pastures as affected by grazing management</b>]]> Signalgrass is largely planted as cultivated pasture in Brazil, but no management targets have been identified. The objective of this study was to evaluate daily herbage accumulation rate (HAR) in Signalgrass pastures grazed at two intensity x two frequency treatments using steers. Target intensities corresponded to 5 and 10 cm post-graze sward height and frequencies were determined by pre-graze sward light interception (LI = 95 or 100%) by the canopy. The trial was carried out from January 2007 to April 2008 on an Entisol. Less frequently grazed pastures had higher HAR during the entire period (29 and 36 kg/ha for 95 and 100%-LI, respectively). There was no intensity effect on HAR, except in the 2007 summer season (January to March) when pastures grazed to 10 cm had a higher HAR (59 kg/ha) than those grazed to 5 cm (45 kg/ha). Total leaf yield increased when regrowth was longer (7930 vs. 8729 kg/ha for 95 and 100%-LI, respectively), but stem and dead material yield increased as well (4877 vs. 7155 kg/ha for 95 and 100%-LI, respectively). The advantages of extending the rest period due to increased HAR was counterbalanced by the great influence of stem and dead material, decreasing pasture leafiness and likely forage nutritive value on the grazed stratum. <![CDATA[<b>Fractional rate of degradation (k<sub>d</sub>) of starch in the rumen and its relation to <i>in vivo</i> rumen and total digestibility</b>]]> Fractional rate of degradation (kd) of fermentable nutrients in the rumen is an important parameter in modern feed evaluation systems based on mechanistic models. Estimates of kd for starch was obtained on 19 starch sources originating from barley, wheat, oat, maize and peas and treated in different ways both chemically and physically. The starch sources were fed in mixed diets together with grass silage and soya bean meal and allocated ad libitum to fistulated dairy cows. The starch content varied between 13 and 35% in ration dry matter for the different starch sources. The design was a series of cross-over experiments with two cows and two periods. Ruminal starch pool was estimated from rumen evacuation and starch flow was estimated by duodenal and faeces sampling. Fractional rate of rumen degradation was estimated from the equation [kd = rumen degraded/rumen pool] and rumen and total digestibility of starch from flow measurements. The relation between kd and rumen digestibility (RD) was estimated to [kd = 1.139 - 3.580*RD + 3.078*RD2; R2 = 0.45; valid for 0.58<RD<0.90] and to total digestibility (TD) to [kd = 7.888 - 19.33*TD + 11.89*TD2; R2 = 0.57; valid for TD>0.81]. It is concluded that the relations between kd and starch digestibility can be used to estimate kd for feed table use from experiments where starch digestibility is known and within the range valid for the equations estimated. <![CDATA[<b>Factors influencing energy demand in dairy farming</b>]]> The efficiency of energy utilization is one of the key indicators for developing more sustainable agricultural practices. Factors influencing the energy demand in dairy farming are the cumulative energy demand for feed-supply, milk yield as well as the replacement rate of cows. The energy demand of dairy farming is assessed on the basis of direct and indirect energy inputs. The comparison of different replacement rates and milk yields shows clearly that both have a considerable influence on the energy intensity of dairy farming. The feed energy requirement/kg milk produced is decreased with an increase in individual performance of the animals. Nevertheless, this effect diminishes gradually with milk yields higher than 8 000 kg/cow/year. Additionally, energy demand increases with higher replacement rates of cows. Milk yields higher than 8 000 kg/cow/year can clearly not compensate for the increase in the cumulative energy demand. Therefore milk yields considerably higher than 8 000 kg/cow/year are not advisable from the view-point of the cumulative energy demand for feed-supply. A decreasing service life of the dairy cows (increasing replacement rate) causes a higher energy demand per kg milk, but its influence is only marginal. <![CDATA[<b>The effect of dietary ionophores on feedlot performance of lambs</b>]]> This study was conducted to evaluate the effect of different rumen fermentation modifiers (ionophores) in feedlot finisher diets on the production performance of S.A. Mutton Merino lambs. Monensin (16.4 mg/kg), lasalocid (33.0 mg/kg) or salinomycin (17.5 mg/kg) was incorporated into a commercial high-protein (398 g CP/kg DM) concentrate. Treatment diets consisted of maize meal (650 g/kg), lucerne hay (150 g/kg) and a protein concentrate (200 g/kg; containing an ionophore or not) to supply isonitrogenous (177 g CP/kg DM) total mixed diets during the experimental period. Sixty lambs (29.7 ± 2.5 kg) were randomly allocated to the treatment groups (n = 15/treatment) and each treatment was further subdivided into five replicates (n = 3/replicate). Individual body weight and average feed intake per replicate were recorded weekly and used to calculate the feed conversion ratio (FCR) and average daily gain (ADG). Ionophore treatment had no effect on any of the feedlot performance parameters measured (feed intake: 1379, 1434, 1534 and 1559 g DM/day; ADG: 298, 314, 340 and 329 g/day; FCR: 4.66, 4.58, 4.51 and 4.74 g DM intake/kg live weight gained for the Control, Monensin, Lasalocid and Salinomycin treatments, respectively. The results suggest the efficiency of the different rumen fermentation modifiers to be similar and financial implications and/or animal preference would influence their usage in sheep diets. <![CDATA[<b>Multi-trait and random regression mature weight heritability and breeding value estimates in Nelore cattle</b>]]> Mature weight breeding values were estimated using a multi-trait animal model (MM) and a random regression animal model (RRM). Data consisted of 82 064 weight records from 8 145 animals, recorded from birth to eight years of age. Weights at standard ages were considered in the MM. All models included contemporary groups as fixed effects, and age of dam (linear and quadratic effects) and animal age as covariates. In the RRM, mean trends were modelled through a cubic regression on orthogonal polynomials of animal age and genetic maternal and direct and maternal permanent environmental effects were also included as random. Legendre polynomials of orders 4, 3, 6 and 3 were used for animal and maternal genetic and permanent environmental effects, respectively, considering five classes of residual variances. Mature weight (five years) direct heritability estimates were 0.35 (MM) and 0.38 (RRM). Rank correlation between sires' breeding values estimated by MM and RRM was 0.82. However, selecting the top 2% (12) or 10% (62) of the young sires based on the MM predicted breeding values, respectively 71% and 80% of the same sires would be selected if RRM estimates were used instead. The RRM modelled the changes in the (co)variances with age adequately and larger breeding value accuracies can be expected using this model. <![CDATA[<b>Effect of dietary lipid sources on lipid oxidation of broiler meat</b>]]> The objective of this study was to investigate the effects of different dietary lipid sources and inclusion levels on lipid oxidation of thigh and breast muscle of male broilers. Eight isoenergetic (15.12 MJ AME/kg DM) and isonitrogenous (222.8 CP/kg DM) diets were formulated, using sunflower oil (SO), high oleic sunflower oil (HOSO), fish oil (FO) and tallow (T) at 30 g/kg and 60 g/kg inclusion levels. Eight hundred, day-old Ross 788 broiler males were randomly allocated to the eight treatments (n = 100) and further subdivided into four replicates/treatment (n = 25). All birds received a standard diet for 14 days whereafter the experimental diets were fed for an additional 28 days until termination of the study. Birds were slaughtered under commercial abattoir conditions at 42 days of age. Carcasses from 12 birds per treatment (n = 12) were trimmed for breast and thigh cuts by removing the skin. Twelve breast and thigh samples from each treatment group were stored at 4 ºC for seven days under an oxygen permeable overwrap film and another 12 breast and thigh samples were vacuum packed and stored at -18 ºC for 100 days. Meat samples were used for thiobarbituric acid reactive substances (TBARS) analysis. Birds fed FO showed significantly more oxidation in both thigh and breast meat than birds from any of the other treatments during storage. These results indicated that dietary lipid sources do influence the lipid oxidation processes of broiler meat. <![CDATA[<b>Effect of lignin type on extent and rate of neutral detergent fibre digestion and potential energy yield</b>]]> The objective of this work was to study the effects of both Klason lignin (KL) and acid detergent lignin (ADL) on in vitro neutral detergent fibre (NDF) digestion (IVNDFd) in an effort to assess if acid labile phenolic compounds affect the rate of degradation (k d). Eighty five forages (lucerne, maize silages and grasses) were analyzed for NDF, ADL, KL and IVNDFd (6, 12, 24, 30, 36, 48, and 96 h fermentations were used for k d estimations). Correlations were estimated among lignin types (KL vs . ADL), lignin and extent of IVNDFd, and lignin type and NDF k d and tested for significance. Within and among all forage types, the correlation between ADL and KL was in general positive when on NDF basis and high and positive when on DM basis (0.77 to 0.90). Within and among all forages, only ADL was consistently negatively correlated with IVNDFd at all time points (-0.54 to -0.94). Correlations among forages for NDF k d and lignin type were not consistent. Among all forages, KL was negatively correlated with IVNDFd and NDF k d. The correlation between IVNDFd and ADL increased as fermentation length increased among all forages. However, the correlation of KL and IVNDFd was greatest up to 48 h of fermentation suggesting that the soluble phenolics affected both the rate and extent of IVNDFd. Unlike ADL, KL disappeared during IVNDFd, and in most forages there was a high negative correlation associated with the difference between KL and ADL (ΔL) and IVNDFd, except for brown midrib hybrids maize and early cut grasses that had a different behaviour. Among forages, a one unit increase in ΔL corresponded to an average 18% decrease in the k d demonstrating that the greater the difference between KL and ADL the lower the rate of digestion. <![CDATA[<b>Rate of intake in wethers fed a temperate pasture with different feeding schedules and supplemented or not with additives</b>]]> The effect of the feeding schedule and the use of additives on the intake and its rate were studied on animals consuming a temperate pasture. Twenty four wethers (47.8 ± 6.4 kg BW), housed in metabolism cages, were fed a fresh pasture (80% Lotus corniculatus) and assigned to four groups. Group AD had forage available all day; group 1D was fed for 6 h/day; group 1D&B was fed 6 h/day plus 2% DM intake level of buffer (75% NaHCO3-25% MgO) and group 1D&S was fed 6 h/day plus 6.2 x 10(9) CFU/animal/day of Saccharomyces cerevisiae. Daily intake and its rate were measured weighing the amount offered and refused every one hour for six hours. Orthogonal contrasts were performed on data to study the effect of feeding schedule, the use of additives and the type of additive used. There were no differences in g of DM ingested/kg BW0.75/day (mean value: 52.8). Groups fed 6 h/day showed a higher rate of intake for every hour studied (i.e. hour 2: AD: 5.9 vs. 6 h/day: 7.2). Within groups fed 6 h/day plus the buffer supplemented one presented the highest cumulative intake, at 20.9 g DMi/kg BW. <![CDATA[<b>Reduction of forces on the teats by single tube guiding in conventional milking parlours</b>]]> Udder health considerably affects the economics of dairy farming. There are different reasons for poor udder health; one of them is the milking technique. In earlier studies it was shown that automatic milking systems (AMS) have advantages over conventional milking systems (CMS). Quarter individual milking and automation are therefore possibilities to improve the milking process. Single tube guiding allows controlling each quarter individually to measure cell count or end the process according to the cows needs. This study evaluates the effect of a single tube milking system used in a conventional milking parlour. Forces on the teats regarding different udder formations and vacuum behaviour were recorded. The investigated single tube milking system MultiLactor® is produced by the company Siliconform GmbH, Türkheim, Germany. Balanced allocation of vertical force for all teats is important for proper and gentle milk withdrawal and to maintain udder health. Measurements of force distribution in AMS and MultiLactor® systems proved their superiority to conventional milking clusters. Furthermore, all the other force directions were reduced to nearly zero in AMS and MultiLactor®. Higher adaptability to irregular udder formations is also expected. In conclusion "wrong" positioning of the teat cups is expected to be solved by implementing clawless milking clusters. <![CDATA[<b>Estimation of genetic parameters of test day fat and protein yields in Brazilian Holstein cattle using an autoregressive multiple lactation animal model</b>]]> This study was aimed to estimate variance components and genetic parameters for daily fat and protein yields of Brazilian Holstein cattle, using an autoregressive test day multiple lactations (AR) animal model. Data consisted of test day (TD) records produced by Holstein cows under milk recording supervised by the Brazilian Holstein Association, calving from 1993 to 2004. Medium to high heritability estimates (from 0.18 to 0.30 and from 0.30 to 0.43 for fat and protein TD yields, respectively) suggest opportunities for larger genetic gain by selection. Results from this study confirm the potential of using TD yields to replace the lactation model to estimate breeding values of Holstein cows in Brazil. Further studies are needed to compare these results with other modelling approaches e.g., the RR model. <![CDATA[<b>Effects of total dissolved solids on the accumulation of Br, As and Pb from drinking water in tissues of selected organs in broilers</b>]]> Water quality constituents ingested through drinking water can affect the animal's physiology negatively and, through bioaccumulation in tissues, pose a biohazard to consumers. The study evaluated the effectiveness of a total dissolved solid (TDS) treatment as a possible alleviator of the accumulation of potentially hazardous chemical constituents (PHCC) in drinking water in broiler tissues. The trial design was 4 treatments x 7 replicates x 12 mixed Ross broilers per replicate. Treatments were T1 = TDS (NaCl) <500 mg/L + Br, As, Pb < 0.005 mg/L, T2 = TDS <500 mg/L + Br, As, Pb 0.1 mg/L, T3 = TDS 1500 mg/L + Br, As, Pb < 0.005 mg/L, T4 = TDS 1500 mg/L + Br, As, Pb 0.1 mg/L, administered through the drinking water from Days 1 to 42. Water intake and growth performance were recorded. Broilers were slaughtered, samples taken of liver, kidney, heart, thigh and breast tissue and analysed for accumulation of elements. TDS significantly (P <0.05) effected the accumulation of elements in some tissues. This confirmed the risk of ingesting PHCC through drinking water, and showed the potential of reducing the risk of accumulating PHCC in selected tissues by the controlled application of TDS in drinking water. However, the concentration attained within a short production period did not exceed the maximum allowable concentration for these elements in broiler tissue destined for human consumption. <![CDATA[<b>Effect of supplementary feed and stocking rate on the production of ostriches grazing irrigated lucerne pasture</b>]]> This study was conducted to determine the effect of two different levels of supplementary feed and two different stocking rates on the production of grazing ostriches. One hundred and seventy ostriches were randomly allocated to four groups and kept on irrigated lucerne pasture with or without supplementary feed from approximately 58 kg to a target weight of 95 kg. The ostriches rotationally grazed lucerne pasture at one of two stocking rates, i.e. 15 birds/ha or 10 birds/ha and were fed one of two levels of supplement i.e. 0 g or 800 g feed/d formulated according to the nutrient requirements of the relevant group of birds. Data were analyzed by ANOVA. There was no interaction between the supplementary feed and stocking rate regarding mean live weight at 54 weeks of age and feed conversion ration (FCR). Data were provided as the two main effects of level of supplementation and stocking rate. Significant differences in mean live weight at 54 weeks of age and FCR of the birds were observed between the different levels of supplementary feed. The parameters measured for the two different stocking rates used in this study (10 birds/ha vs. 15 birds/ha) did not differ from each other and did not influence either mean live weight at 54 weeks of age, average daily gain (ADG) or FCR. The two groups which received 800 g supplementary feed/d reached slaughter weight (95 kg) within the set of 54 weeks of grazing for the trial, while the two groups which received no supplementary feed did not achieve slaughter weight by 54 weeks on the pasture. Ostriches receiving supplementation of 800 g/bird/day had significantly better FCR's than birds receiving no supplementation. There was a significant interaction between level of supplementary feed and stocking rate regarding ADG of the birds. As stocking rate increased, average daily gains of birds receiving no supplementary feed declined. This study indicates that ostriches being kept on grazing and receiving supplementary feed will exhibit improved and faster growth rates than ostriches which only have access to grazing and receive no supplementary feed. <![CDATA[<b>The nutritive value of South African <i>Medicago sativa</i> L. hay</b>]]> A study was conducted to evaluate the variation and expand the existing and limiting nutritive value database of Medicago sativa L. hay (168 near-infrared reflectance spectroscopy spectrally selected samples) in South Africa. The highest moisture content recorded (140 g/kg) was safely below the critical moisture level of 160 g/kg for effective storage. Coefficient of variation (CV) ranged from 1.2% for dry matter (DM) up to 66.2% for acid detergent fibre-crude protein (ADF-CP). The average ash content was 130 g/kg (73 to 295 g/kg), indicating soil contamination. Fibre fractions varied as follows: acid detergent fibre (ADF) (213 to 473 g/kg), neutral detergent fibre (NDF) (289 to 659 g/kg), lignin (43 to 163 g/kg), cellulose (163 to 364 g/kg) and hemicellulose (53 to 199 g/kg). The mean IVOMD for both 24 and 48 h (693 and 732 g/kg DM, respectively), was representative (CV = ± 8%) of the Medicago sativa L. hay population. Crude protein (CP) (average = 207 g/kg DM) consists of 76.9% true protein. According to ADF-CP, 6% of the samples were heat damaged. High mean Ca (13.5 g/kg), P (25.3 g/kg) and Fe (874 mg/kg) values were recorded. <![CDATA[<b>Prediction of chemical composition of South African <i>Medicago sativa</i> L. hay from a near infrared reflectance spectroscopy spectrally structured sample population</b>]]> The near infrared reflectance spectroscopy (NIRS) to predict chemical and digestibility parameters was investigated. Samples (n = 168) representing the spectral characteristics of the South African Medicago sativa L. hay population were chemically analysed for the development of calibration equations. Values for r² and ratio of prediction to deviation (RPD) used as estimates of calibration accuracy for these parameters were classified as follows: good for dry matter (DM) (r² = 0.97; RPD = 4.84), crude protein (CP) (r² = 0.97; RPD = 4.57), acid detergent fibre (ADF) (r² = 0.95; RPD = 3.97), neutral detergent fibre (NDF) (r² = 0.95; RPD = 3.99), lignin (r² = 0.94; RPD = 3.61), ash (r² = 0.93; RPD = 3.12) and chloride (Cl) (r² = 0.95; RPD = 3.74); intermediate for NDF-crude protein (NDF-CP) (r² = 0.91; RPD = 2.96), sugar (r² = 0.91; RPD = 2.82), in vitro organic matter digestibility at 24 hr (IVOMD24) (r² = 0.90; RPD = 2.84) and 48 hr (IVOMD48) (r² = 0.89; RPD = 2.70); and low (RPD <2.31) for soluble protein (SP), ADF-crude protein (ADF-CP), fat, starch, NDF digestibility (NDFD) and the macro minerals (Ca, P, Mg, P, Na and S). The results recorded in the present study indicated that the NIRS technique is acceptable for DM, CP, ADF, NDF, lignin, ash and Cl analysis and for inclusion in quality models. <![CDATA[<b>Evaluation of models for assessing <i>Medicago sativa</i> L. hay quality</b>]]> A study was conducted to evaluate current proposed models for assessing Medicago sativa L. hay quality, using near infrared reflectance spectroscopy (NIRS) analyses and Cornell Nett Carbohydrate and Protein System (CNCPS) milk production prediction as a criterion of accuracy. Application of the theoretically-based summative total digestible nutrients (TDNlig) model of Weiss et al. (1992), using lignin to determine truly digestible NDF, explained almost all of the variation in milk yield (MY) (r² = 0.98). However, this model involves high analysis costs to develop and maintain NIRS calibrations and several of its components were poorly predicted by NIRS and therefore, not suited for quality assessment in practice. Current available models (forage quality index (FQI), relative forage quality (RFQ); relative feed value (RFV)) for assessing Medicago sativa L. hay quality revealed lower accuracies (r² = 0.83, r² = 0.76, r² = 0.61, respectively), especially when protein was included in the model (total forage quality index (TFI); r² < 0.49). The developed empirical equation named lucerne milk value (LMV), including ADF, ash and lignin (Y = b0 - b1ADF - b2ash - b3lignin) (r² = 0.96), proved to be the most practical, simplistic, economical and accurate quality evaluation model for commercial application. <![CDATA[<b>Can repeated superovulation and embryo recovery in Boer goats limit donor participation in a MOET programme?</b>]]> This study evaluated the effect of repeated superovulation and embryo recovery in 15 Boer goat does. Does were synchronised for oestrus using CIDR's for 17 days and superovulated with pFSH during the natural breeding season (autumn). Cervical inseminations with fresh undiluted semen were performed 36 h and 48 h following CIDR removal and the embryos surgically flushed six days after the second AI. Does superovulated for the first time recorded a shorter mean (± s.e.) induced duration of oestrus (20.8 ± 1.0 h), when compared to those repeatedly superovulated (30.4 ± 6.7 h). The mean (±s.e.) number of structures and embryos recovered were significantly lower in does treated repeatedly (6.0 ± 1.7 and 3.8 ± 1.7) than does superovulated for the first time (12.9 ± 0.5 and 11.7 ± 0.5), respectively. The mean (±s.e.) number of unfertilised ova per donor was significantly higher in repeatedly superovulated does (5.5 ± 1.6), compared to does superovulated for the first time (0.1 ± 0.1). The fertilisation rate and the number of transferable embryos were significantly lower in does treated repeatedly, compared to does superovulated for the first time. These results indicate that the number of times that a Boer goat doe can be utilised as the embryo donor may be limited to three times. <![CDATA[<b>Effect of cryoprotectant on the cryopreservation of South African Kolbroek pig semen</b>]]> The study evaluated the effect of different cryoprotectants on post-thaw survival and motility of Kolbroek sperm. Semen from Kolbroek boars was collected with the gloved hand technique. Ejaculates were diluted with Beltsville thawing solution (BTS) at a ratio of 1 : 1 prior to freezing. Semen was diluted with egg yolk tris; thereafter, one of the three cryoprotectants (14% glycerol, 14% DMSO or 7% glycerol + 7% DMSO) were added. Diluted samples were then loaded into 0.5 mL straws and cooled with a programmable freezer. Thereafter the semen straws were plunged directly into liquid nitrogen (-196 ºC) and stored for 48 h. Frozen straws were thawed at 39 ºC for a minute and evaluated for sperm motility and survival at 0, 30, 60 and 90 min post-thaw. The post-thaw sperm survival frozen using glycerol as a cryoprotectant was significantly higher immediately after thawing, compared to DMSO, however, similar to the combination of glycerol and DMSO. There was no significant difference on motility rate immediately (0 min) post-thaw between the three cryoprotectants. Sperm cryopreserved with glycerol exhibited a significantly higher percentage motility at 30, 60 and 90 min post-thaw than in the other cryoprotectants. Based on sperm motility, glycerol was a better cryoprotectant for cryopreservation of Kolbroek boar sperm. <![CDATA[<b>Modelling the long-term consequences of undernutrition of cows grazing semi-arid range for the growth of their progeny</b>]]> Undernutrition of cows grazing semi-arid range as a result of drought or heavy stocking rates reduces prenatal and pre-weaning growth of their calves. A mechanistic model has been developed that simulates the productivity of vegetation and cattle on semi-arid savanna rangeland in southern Africa. When cows are stocked at 0.200 cows/ha instead of 0.123 cows/ha the model predicted that empty body weights of their progeny at birth and weaning would be reduced by 2.9 and 43.8 kg, respectively. If all young animals are stocked at 0.22 animals/ha after weaning, differences in empty body weight at weaning are predicted to persist almost unchanged for a further two years. The model also predicted that undernutrition of cattle aged 21 months would be followed by partial compensatory growth. Comparison of simulated results with data from experiments in Zimbabwe indicates that the model realistically simulates the effects of stocking rate on cattle growth. <![CDATA[<b>Production and breeding performance of South African dairy herds</b>]]> Comparisons between production and breeding potential of different feeding systems (Concentrates, Mixed and Pastures) in South Africa were made. Data of active cows participating in performance testing as at November 2007 were used. Holstein cows numbered 68280 in 254 herds and Jersey cows 51275 in 248 herds. Average milk production and lactation number were 8147 ± 2260 and 2.9 ± 1.8 for Holstein and 5347 ± 1156 and 3.1 ± 2.0 for Jersey, respectively. Most Holstein and Jersey herds (53%) were on Mixed rations, followed by Concentrates (28%) and Pastures (19%). Milk production was 9967 ± 2022; 6996 ± 1623 and 7143 ± 1549 kg for Holstein and 6385 ± 1233; 5155 ± 955 and 4753 ± 1022 kg for Jersey cows, respectively, for Concentrates, Mixed and Pasture systems. Most sires used were local (49% of Holstein sires and 68% of Jersey sires). Imported Holstein sires were mostly from USA (30%) and The Netherlands (17%), and foreign Jersey sires (26%) were mostly from the USA. Farmers seemed to select the same sires on the different feeding regimes. Differences between feeding regimes were significant. <![CDATA[<b>The influence of supplementary light on Dorper lambs fed intensively</b>]]> The objective of this trial was to quantify the differences in average daily gain (ADG), backfat thickness (BFT), eye muscle area (EMA), fat thickness (FT) on different body parts, the feed conversion ratio (FCR), body measurements and the weight of internal organs of Dorper lambs exposed to supplemented light. For this study 120 Dorper lambs (115 ± 10 days old), weighing 29.8 ± 5.01 kg, were used. The lambs were randomly divided into three homogeneous groups (20 castrated and 20 intact males/group). Two groups were then exposed to either 16 h or 24 h of supplemented light at 145 lux, and a control the normal photoperiod. The animals were fed ad libitum with pellets containing 9.5 MJ ME/kg DM and 120 g CP/kg in open pens. The animals were weighed every seven days while ultrasound scanning of the EMA and BFT was done at the beginning and the end of the 35 d trial. The ADG, FCR and feed intake (FI) were calculated at the end of the trial. Linear body measurements including shoulder height, body length and heart girth were taken at days 1 and 35. All the animals were slaughtered at the end of the trial. The carcasses were weighed, graded and the FT was measured with a caliper. It was concluded that there are no differences between treatments in terms of body measurements, ultrasound scanning, ADG and FCR. <![CDATA[<b>Influence of dietary energy level on the production of breeding ostriches</b>]]> A study was conducted to determine the influence of dietary energy level on the production of breeding ostriches. Six diets varying in ME content (7.5, 8.0, 8.5, 9.0, 9.5 and 10.0 MJ ME/kg feed) were provided to both males and females at an average rate of 3.4 kg/bird/day. Dietary protein and lysine levels were held constant respectively at 120 (g/kg feed) and 5.8 (g/kg feed). The trial ran over one breeding season and production records recorded included egg production, chick production, number of infertile eggs, number of dead-in-shell eggs and weight change of breeders. No significant differences were observed for total eggs produced per female per season (44.3 ± 7.6), number of chicks hatched (15.6 ± 4.1), number of infertile eggs (11.8 ± 3.9) and for number of dead-in-shell eggs (11.9 ± 3.1). Analysis of variance revealed no significant difference in the weight change of female birds on different treatments, although regression analysis revealed an increase of 2.4 kg per female bird per 0.5 MJ increase in dietary energy value of the feed. Significant differences in the weight change of male breeders were observed which ranged between 6.3 ± 2.7 kg and 18.4 ± 2.8 kg over the breeding season. Overall, the weight of male breeders increased by 1.9 kg per 0.5 MJ increase in dietary energy content (R² = 0.09). It was concluded that the energy supplied for both male and female breeders was in excess of their requirements, since both sexes increased in weight over the season. <![CDATA[<b>Improving the quality of wool through the use of gene markers</b>]]> This study aimed at identifying gene markers associated with wool quality traits in Merino and Merino Cross sheep using a candidate gene approach. Polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis was used to identify sequence variation in the KAP1.3 and K33 genes, while agarose gel electrophoresis was used to detect length variation in the KAP1.1 gene. Two half-sib families (SL1 and SL2) were created for analysis and wool samples were collected from the mid-side region of the SL1 progeny at 12, 24 and 36 months of age, and of the SL2 progeny at 12 months of age. The association of alleles was analysed for each year of phenotypic data by an analysis of variance (ANOVA) tests, using SPSS® version 15. Analysis of each of KAP1.1, KAP1.3 and K33 genes revealed potential gene markers to select for animals with increased staple length, increased staple strength, higher yield, whiter and brighter wool. The results obtained are consistent with KAP1.1, KAP1.3 and KRT1.2 being clustered on one chromosome. Results also indicated that the keratin genes on chromosome 11 are recombining relatively frequently at recombination "hotspots". It appears as though genes coding for the KRTs and KAPs have the potential to impact on wool quality and could potentially be exploited in gene marker-assisted selection programmes in the wool industry for the rapid conversion of wool from one type to another <![CDATA[<b>Effect of heat stress on six beef breeds in the Zastron district</b>: <b>the significance of breed, coat colour and coat type</b>]]> A study was done to determine which factors had the greatest influence on a heifer's susceptibility to heat stress. Parameters tested were breed, coat colour, coat score, hide thickness, weight gain, respiration rate and body condition score. The study was conducted in the southeastern Free State. Afrikaner, Bonsmara, Braford, Charolais, Drakensberger and Simmentaler heifers were subjected to a heat tolerance trial. A total of 60 heifers, 10 of each breed were evaluated. Rectal temperature (Tre) was used as a parameter to determine heat stress. The heifers were evaluated on 10 days, at 14:00 during the winter of 2007 and on seventeen days, at 14:00 during the summer of 2007/8 (after 1 h in the sun, no access to shade). In winter a significant difference in rectal temperature Tre between breeds was measured on seven occasions. Phenotypical factors tested for did not affect Tre in winter. In summer significant differences in Tre were measured on 12 occasions between breeds. The following factors had a significant influence on Tre in the following breeds: Afrikaner - hide thickness, Bonsmara - hide thickness, Charolais - coat score. <![CDATA[<b>Silage fermentation attributes and certain rumen parameters in sheep fed two grass silages harvested at different stages of maturity</b>]]> The aim of this study was to compare two tropical grass species, Panicum maximum and Digitaria eriantha, in terms of silage fermentation attributes and certain rumen fermentation characteristics of silage made either at the boot or full bloom stages of growth. A lower silage pH was recorded for the D. eriantha than for the P. maximum silage. Neither species nor maturity stage had a significant effect on silage ammonia nitrogen, or lactic, acetic and butyric acid concentrations. For P. maximum silage total N was higher at full bloom than at the boot stage. D. eriantha had a higher total nitrogen content than P. maximum silage at the boot stage. Rumen pH was lower in sheep fed D. eriantha than P. maximum silage. In P. maximum fed sheep, a higher rumen NH3-N concentration was recorded when silage from the full bloom stage was fed compared to silage from the boot stage. In sheep fed D. eriantha silage, higher concentrations of acetic, propionic, butyric and total volatile fatty acids in the rumen were recorded from full bloom than from the boot stage. Neither species nor stage of maturity had significantly influenced the acetic : propionic acid ratio. The results suggested no significant difference between the species, but the full bloom stage showed a higher nutritive value and better preservation compared to the boot stage silage in both D. eriantha and P. maximum silage. <![CDATA[<b>Influence of grass species and stage of maturity at ensiling on intake and partial digestibility by sheep</b>]]> The aim of this study was to compare intake and partial digestibility of organic matter (OM) and nitrogen (N) of two ensiled tropical grass species, P. maximum and D. eriantha, made either at the boot or full bloom stage of growth. Intake and digestibility were determined by the double marker technique where Yb and Cr were infused continuously into the rumen with a peristaltic pump. Except for OM disappearance in the digestive tract, neither species nor stage of harvesting had an effect on intake, digesta flow and OM disappearance within the rumen and small intestine. For P. maximum silage, N intake (g/d) was higher at the full bloom than at the boot stage. Total abomasum N flow (g/d), non-ammonia nitrogen (NAN) flow (g/d), NAN flow per N intake and NAN disappearance as % of N intake in the gastrointestinal tract (GIT) were higher for sheep fed on D. eriantha than P. maximum silage made at full bloom. In D. eriantha silage NAN disappearance was higher for silage at full bloom than D. eriantha silage at boot stage. The true N-digested (%), however, did not differ significantly between the species or stage of maturity. In terms of NAN disappearance in the lower GIT it is evident that silage made from D. eriantha at the full bloom stage is superior to silage made at the boot stage, as well as to silage made from P. maximum. <![CDATA[<b>Influence of species/cultivar and season on the quality of <i>Atriplex</i> grown at different sites in South Africa</b>]]> Atriplex species/cultivars [Atriplex nummularia, A. canescens (Santa Rita) and A. canescens (Field Reserve 1)] were compared in terms of chemical composition and in vitro digestibility. The plant material was sampled at different seasons (autumn and winter) and from different sites (Hatfield in the Gauteng Province and Mier and Lovedale, both in the Northern Cape Province) and were analysed for crude protein (CP), neutral detergent fibre (NDF) and in vitro digestibility (IVOMD). The CP and IVOMD of the leaves were higher than the stem for the Atriplex species. Leaf percentage for the autumn samples was not affected by species at Hatfield and Mier, but A. canescens (Field Reserve 1) had lower leaf percentage at Lovedale as well as for winter samples at Hatfield. At Lovedale, however, A. nummularia had the highest leaf : stem ratio compared to A. canescens (Santa Rita) and A. canescens (Field Reserve 1). Atriplex nummularia had a higher CP concentration than A. canescens (Field Reserve 1) and A. canescens (Santa Rita) at both Mier and Lovedale, but species/cultivar had no effect on CP concentration at Hatfield. Autumn samples had a higher CP concentration than winter samples at both Mier and Lovedale, but season had no effect on the N concentration at Hatfield. Atriplex nummularia had a lower NDF and higher IVOMD concentration compared to A. canescens (Santa Rita) and A. canescens (Field Reserve 1). Autumn samples were less fibrous and more digestible than winter samples. Atriplex nummularia seems to be better in terms of its nutritive value compared to A. canescens (Santa Rita) and A. canescens (Field Reserve 1), with better quality forage in autumn than winter. <![CDATA[<b>The effect of breed on the survivability and motility rate of cryopreserved cock semen</b>]]> This study evaluated the effect of breed on the survivability and motility rate of cryopreserved cock semen. Semen from three cock breeds; White Leghorn (WL), Ovambo (OV) and Potchefstroom Koekoek (PK) was collected by means of the abdominal massage technique. Following semen collection, sperm were analyzed for motility and survivability with the use of contrast light BHTU microscope (20 x magnification). The semen was diluted (1 : 2 v/v) with egg yolk citrate (EYC) (extender A) and thereafter with extender B (EYC + 5% DMSO). The equilibration after each dilution was 2 h at 5 ºC. The diluted samples were evaluated for sperm concentration, motility, survivability and pH. The samples were then loaded into straws and cooled in programmable freezer from 5 ºC to -20 ºC at the rate of 1 ºC/minute. Semen straws were then exposed to liquid nitrogen vapour (-80 ºC) for five minutes, plunged directly into liquid nitrogen (-196 ºC) and stored for a week or more. Frozen straws were thawed at 5 ºC and evaluated at 0, 30, 60 and 90 min post-thaw. From the results there was no significant effect of breed on the survival and motility of fresh-diluted and frozen-thawed semen at 30 and 90 min post-thaw in all breeds. The sperm survivability of the PK breed was significantly higher than that of the WL breed. However, there was no sperm survivability difference between PK and OV breed immediately after thawing. The cryopreservation and thawing processes affected the survivability and motility of sperm of all poultry breeds negatively. <![CDATA[<b>Rumen pH and NH<sub>3</sub>-N concentration of sheep fed temperate pastures supplemented with sorghum grain</b>]]> The aim of this study was to evaluate the effect of sorghum grain supplementation on ruminal pH and NH3-N concentration of wethers consuming a fresh temperate pasture (Lotus corniculatus) in metabolism cages. Sixteen Corriedale x Milchschaf wethers were fed temperate pastures ad libitum and were non-supplemented or supplemented with ground sorghum grain at 5, 10 or 15 g/kg of their body weight (BW). Rumen fluid samples were collected at 0, 1, 2, 3, 4, 5 and 6 h after supplementation through permanent tubes inserted in the rumen. Ruminal pH was measured immediately and NH3-N concentration was determined by direct distillation. Mean daily pH values for non-supplemented wethers and supplemented with 5, 10 and 15 g/kg of their BW were 6.45, 6.14, 6.09 and 5.43, respectively. Significant differences in pH were found between the 15 g/kg supplemented group and non-supplemented, 5 and 10 g/kg supplemented groups, while a trend was found between non-supplemented and 10 g/kg supplemented group. After 0 h, all mean pH values for the non-supplemented group were above 6.15, while values for the 10 and 15 g/kg supplemented groups were below 6.2 and 6.0, respectively. No differences in NH3-N concentration among groups (mean = 37.15 mg/100 mL), between time or interaction between time and treatment were found. There was a correlation between pH and NH3-N when all measurements were considered. Ground sorghum grain supplementation significantly reduced rumen pH when 15 g/kg of BW was provided to wethers fed temperate pastures, but it did not affect NH3-N concentration. <![CDATA[<b>Dry matter intake and digestibility of temperate pastures supplemented with sorghum grain in wethers and heifers</b>]]> The aim of this study was to evaluate the effect of sorghum grain supplementation on total and forage dry matter (DM) intake and digestibility of wethers and heifers consuming temperate pasture. Twenty four Corriedale x Milchschaf wethers and 24 crossbred heifers fed temperate pasture were non-supplemented or supplemented with sorghum grain at 5, 10 or 15 g/kg body weight (BW). Offered and refused feed were measured for 11 days and faeces voided were recorded daily during five days. Samples of feeds and faeces were collected daily and analyzed for DM. Supplement inclusion led to an inverse response in both species. Total dry matter intake (TDMI) of supplemented wethers was 20% lower than non-supplemented ones. Forage dry matter intake (FDMI) averaged 40% less in supplemented groups than in non-supplemented ones. Heifers receiving the supplement had 23% more TDMI but 10% less FDMI than non-supplemented, and lower FDMI was observed as supplementation increased. Dry matter digestibility (DMD) was 0.69 for wethers and 0.65 for heifers, with no differences between treatments. When the results from all animals were analyzed together, no differences on TDMI, lower FDMI and higher DMD were observed for the supplemented groups. In conclusion, sorghum grain supplementation affected TDMI differently in the two species, reducing TDMI in wethers and increasing TDMI in heifers. Supplementation reduced FDMI, the reduction being higher in wethers than in heifers. Dry matter digestibility of supplemented diets was higher, probably due to grain digestibility. <![CDATA[<b>Heat stress in Tunisia</b>: <b>effects on dairy cows and potential means of alleviating it</b>]]> The aim of this study was to evaluate the effect of sorghum grain supplementation on total and forage dry matter (DM) intake and digestibility of wethers and heifers consuming temperate pasture. Twenty four Corriedale x Milchschaf wethers and 24 crossbred heifers fed temperate pasture were non-supplemented or supplemented with sorghum grain at 5, 10 or 15 g/kg body weight (BW). Offered and refused feed were measured for 11 days and faeces voided were recorded daily during five days. Samples of feeds and faeces were collected daily and analyzed for DM. Supplement inclusion led to an inverse response in both species. Total dry matter intake (TDMI) of supplemented wethers was 20% lower than non-supplemented ones. Forage dry matter intake (FDMI) averaged 40% less in supplemented groups than in non-supplemented ones. Heifers receiving the supplement had 23% more TDMI but 10% less FDMI than non-supplemented, and lower FDMI was observed as supplementation increased. Dry matter digestibility (DMD) was 0.69 for wethers and 0.65 for heifers, with no differences between treatments. When the results from all animals were analyzed together, no differences on TDMI, lower FDMI and higher DMD were observed for the supplemented groups. In conclusion, sorghum grain supplementation affected TDMI differently in the two species, reducing TDMI in wethers and increasing TDMI in heifers. Supplementation reduced FDMI, the reduction being higher in wethers than in heifers. Dry matter digestibility of supplemented diets was higher, probably due to grain digestibility. <![CDATA[<b>Growth and development of the reproductive organs of female breeding ostriches</b>]]> A study was conducted to determine the growth rate of the reproductive organs of breeding female ostriches, which may be used in a prediction model for estimating nutrient requirements of breeders. Forty breeding female ostriches were sampled over an eight week period (five per week) starting at the onset of the breeding season. The ovary and oviducts were collected and weighed at each slaughter interval. No significant trend in the weight of the oviduct of the ostriches could be observed over the 49 d period, this weight being highly correlated with the body weight of the ostrich, whereas the ovary weight tended to be correlated with the time after the onset of the breeding period, although the variation in weights both within and between weights was very high. The variation in the weight of the ovary probably reflects differences in the laying pattern of individuals, and this lends itself to simulating the ovulatory cycle and consequently gaining a better understanding of the process, which would in turn aid in determining the requirement for the nutrients responsible for the growth of the ova. <![CDATA[<b>Heat tolerance of Nelore, Senepol x Nelore and Angus x Nelore heifers in the southeast region of Brazil</b>]]> The Brazilian beef industry has experienced an increase in the utilization of adapted and non-adapted Bos taurus breeds in crossbreeding systems. In spite of this, little is known about the adaptability of these groups and of their crossbred progeny when raised in a tropical climate. The aim of this study was to evaluate the physiological responses related to adaptability of Nelore (NE), crossbred Angus x Nelore (TA) and Senepol x Nelore (SN) cattle submitted to a heat tolerance trial. The study was conducted in the Southeast - Embrapa Cattle (CPPSE), São Carlos, Brazil. During the summer of 2008, 45 heifers, 15 of each breed type, were evaluated over three days: at 7:00 a.m. (resting measure), at 13:00 (after six hours in the sun with no access to water and shade) and at 15:00 (after a further two hours in the sun with access to shade). Rectal temperature and sweating rate were measured and the data were analyzed using restricted maximum likelihood. The effect of breed type was significant for rectal temperature only at 15:00 and for the sweating rate at all three test periods. Based on these results, Senepol x Nelore heifers showed a better adaptation in the heat tolerance test than the other breed types. <![CDATA[<b>Long term use of bovine somatotropic (bST) on reproduction and health of Nili-Ravi buffaloes</b>]]> The study was conducted to determine the effect of long term use of bovine somatotropic hormone (bST) on days to first oestrus post-partum, number of services per conception, pregnancy rate, lactation length, dry period and calving interval for a period of three years, from 2004 to 2007. Thirty Nili-Ravi lactating buffaloes with approximately similar milk yields and stage of lactation were selected and randomly allocated to two treatments, A and B, with 15 animals in each group. Group A served as control while animals in group B were given injections of bovine somatotropic hormone (250 mg intramuscular per animal) at intervals of 14 days over a period of three years. The calving interval, dry period and lactation length were shorter by 71, 63.9 and 7 days, respectively, in the treated compared with the control group. The days to first oestrus post-partum, service period and services per conception were 160 ± 56.9 vs.98.2 ± 76.4 days, 207.0 ± 85.0 vs. 115.1 ± 107.0 days and 1.47 ± 1.1 vs. 1.31 ± 0.5 in group A vs. B, respectively. Statistically, differences were significant for post-partum oestrous and service period but for services per conception the difference was non-significant. Prevalence of mastitis was significantly higher in the treated animals while differences in body weights of the animals in the groups were not significant. <![CDATA[<b>Influence of a polyclonal antibody preparation on the<i> in situ</i> degradability of three energy sources</b>]]> The objective of this study was to evaluate the effect of a polyclonal antibody preparation (PAP) against specific ruminal bacteria on the in situ degradability of dry-grounded maize grain (DMG), high moisture maize silage (HMMS) starch and citrus pulp (CiPu) pectin. Nine ruminally cannulated cows were used in a 3 x 3 Latin square design, replicated three times in a factorial arrangement of treatments of two rumen modifiers represented by monensin and PAP plus a control group, and the three energy sources (DMG, HMMS and CiPu). Each period had 21 days, where 16 were used for adaptation to treatment and five for data collection. The group treated with PAP showed an effect on the soluble fraction ("a") of DMG starch, decreasing it by respectively 45.3% and 45.4% compared to the CON and MON groups. No effect of PAP was observed for any in situ degradability parameters of starch from HMMS or pectin of CiPu. It was concluded that the polyclonal antibody preparation had limited effect on the in situ degradability of the tested energy sources. <![CDATA[<b>The effect of season on aspects of <i>in vitro</i> embryo production in sub-fertile beef cows</b>]]> This study was conducted to investigate the possible effect of season on in vitro embryo production (IVEP) in sub-fertile beef cows. Forty beef (40) cows of different breeds and parities were used in a trial conducted as part of a commercial embryo production programme. Animals were subjected to a once a week ultrasound guided oocyte recovery procedure (OPU) and all oocytes were entered in a commercial IVEP programme. A significant difference in follicular populations could be established for different months of the year. As for recovery rate, oocyte quality and embryo production, no significant differences could be established. However, the embryo production per OPU session per cow showed a definite seasonal pattern with low production during hotter months, a steady increase during the colder months and a peak in spring. This information should be helpful in the future planning of IVEP programmes for fertility-impaired cows. <![CDATA[<b>Monensin and protein supplements on methane production and rumen protozoa in bovine fed low quality forage</b>]]> This study aimed at evaluating the effect of sodium monensin and protein supplementation in the enteric methane production and the population of ruminal protozoa in bovine fed Brachiaria brizantha Marandu cultivar hay. The treatments were: mineralized salt, mineralized salt with monensin, protein-enriched salt and protein-enriched salt with monensin. The experimental outline was in a 4 x 4 Latin square. The protein supplementation increased the dry matter intake and the total concentrations of rumen ciliate protozoa. Monensin eliminated the rumen fauna and reduced the methane production. Methane production was 19.13; 15.73; 24.35 and 11.52 g/kg of ingested DM when mineralized salt, mineralized salt with monensin, protein-enriched salt and protein-enriched salt with monensin were supplied, respectively. The association between the inputs allows for a reduction in the methane production without a reduction in dry matter intake. <![CDATA[<b>Volatile fatty acids in cattle supplemented with protein-enriched salt and sodium monensin</b>]]> The effects of sodium monensin and protein supplements on volatile fatty acid production were studied in a 4 x 4 Latin Square design, using four female bovines equipped with rumen fistulae and fed Brachiaria brizantha Marandu cultivar hay. The treatments were organized in a 2 X 2 factorial array (with or without 160 mg of sodium monensin/animal/day and with or without protein supplements). Protein supplementation increased the concentration of acetic acid and sodium monensin reduced the concentrations of acetic and butyric acids and the acetic : proprionic ratio, both with and without protein supplements, except for the material collected at 8 h. Sodium monensin reduced the total concentration of fatty acids only in the material collected at 0 h, while protein supplementation increased the concentration of fatty acids at 4, 6 and 8 h. Used together, they increased the molar concentration of propionate in the rumen fluid, without decreasing the total concentration of fatty acids. <![CDATA[<b>Comparison of growth rates in the tissues of primal cuts of Canadian composites</b>]]> Beef composites (C) have combined favourable traits of pure breeds. The objective was to compare the growth rates (GR) of muscle (M) and fat (F) in the primal cuts of serially harvested Beefbooster® C types (SM = C of small breeds, AH = C of Angus and Hereford and GLC = C with Gelbvieh, Limousin or Charolais terminal sires) from 274 - 456 days (d) of age to determine harvest times that reflect an increase M and a decrease F. Analysis of covariance obtained the slopes (GR/d) for M and F within each cut and C type. In the SM and AH the GR of overall F in all primal cuts exceeded that of M by 24.8 g/d and 4.91g/d respectively, while in GLC the gain of M exceeded that of F by 6.77 g/d. We suggest that the SM and AH could be harvested at least 30 d earlier than GLC thereby increasing the proportion of carcass M and decreasing F. <![CDATA[<b>Assessment of Nili-Ravi buffalo (<i>Bubalus bubalis</i>) semen by MTT reduction assay</b>]]> MTT (3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay is commonly used to validate the viability of metabolically active cells. The study was conducted to examine and validate the MTT test to assess the sperm viability of Nili-Ravi buffalo bulls and compare the efficiency of the test with the supra-vital staining technique (eosin-nigrosine) and hypo-osmotic swelling test. Fresh semen samples from breeding Nili-Ravi buffalo bulls (n = 20) were collected using an artificial vagina. After assessing the quality of semen for normal parameters, the MTT assay was carried out in phosphate buffer saline. Results revealed a high significant correlation (r = 0.995) between the viability of sperm and the rate of reduction of MTT. The other proportions of some semen samples showed a weak relationship between the eosinnigrosine method (r = -0.32), hypo-osmotic swelling test (r = -0.12) and motility (r = -0.08). However, the MTT assay was found to be superior to other tests as it was able to determine those sperm which were more than 90% viable. In conclusion, the MTT assay is a simple, robust test that can be used to select Nili-Ravi buffalo bulls on the basis of sperm quality. <![CDATA[<b>A model for assessing <i>Medicago Sativa</i> L. hay quality</b>]]> A study was conducted to identify chemical parameters and/or models for assessing Medicago sativa L. (L) hay quality, using near infrared reflectance spectroscopy (NIRS) analysis and Cornell Net Carbohydrate and Protein System (CNCPS) milk prediction as a criterion of accuracy. Milk yield (MY) derived from the CNCPS model, by replacing the average L hay in a complete diet with 168 representative South African L hay samples, was used as a criterion to evaluate and/or develop models for L hay quality grading. The best single predictor of MY was the acid detergent fibre (ADF) content of L hay, which explained 67% of the measured variation. A multiple linear equation (Y = 64.18 - b1ADF - b2ash - b3lignin) explains 96% of the measured variation in MY. The relatively poor performance of crude protein (CP) (r² = 0.04) and other protein related parameters (r²< 0.25; adjusted-crude protein, ADF-CP, neutral detergent fibre-CP and soluble protein) in predicting MY suggests that protein content of L hay is an unreliable indicator of L hay quality. It is clear that MY derived from the CNCPS model by replacing L hay in a basal diet with others in the South African L hay population can be significantly predicted with high accuracy by the developed empirical model named lucerne milk value (LMV) consisting of only ADF, ash and lignin. <![CDATA[<b>Serum progesterone as an indicator of cyclic activity in post-partum goat does</b>]]> The aim of this trial was to assess post-partum ovarian activity of the does of two South African goat breeds from their serum progesterone concentrations. Between seven and 100 days post-partum, does from the Boer goat breed and an indigenous rural goat type were allocated to two nutritional treatments within breed. One group per breed received a concentrated diet in an intensive feeding programme. The other group per breed was subjected to a low level of nutrition through the grazing of the natural pasture in an extensive (veld) grazing system. Blood samples were collected weekly from five does per breed per treatment. Serum progesterone concentrations were determined using a Gamma Coat TM [128] progesterone radioimmunoassay kit (Sorin Diagnostics, France). Large variations in serum progesterone concentrations were recorded within and between breeds and nutritional regimens. Irrespective of breed, in the extensive groups subjected to the low level of nutrition, mean peak serum progesterone concentrations never exceeded 0.2 ng/mL. This suggests that throughout the experimental period, ovarian activity remained low in the extensive groups. It was concluded that nutritional regimen plays a significant role in ensuring high ovarian activities. Furthermore, the higher mean serum progesterone levels in the Boer goat indicate an earlier and higher oestrous activity, compared to the indigenous does. <![CDATA[<b>Effects of varying levels of thermostable xylanase, amylase and protease (TXAP) composite enzyme supplement on body growth of broiler chickens</b>]]> A dose-response experiment was conducted with Ross broiler chickens from day-old to 42d of age to determine the effect of exogenous composite enzyme (TXAP) on broiler performance and the most beneficial rate of inclusion. Broiler chickens were fed maize-soyabean based feed with one diet unsupplemented and five other diets supplemented with increasing levels of TXAP, from 0.5 to 2.5 g/kg. The inclusion of TXAP did not have any significant improvement on broiler performance. The lack of response in this experiment might be due to the quality of ingredients used.