Scielo RSS <![CDATA[South African Journal of Animal Science]]> http://www.scielo.org.za/rss.php?pid=0375-158920100005&lang=en vol. 40 num. 5 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Introduction</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500001&lng=en&nrm=iso&tlng=en <![CDATA[<b>Scientific research</b>: <b>the planning process</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500002&lng=en&nrm=iso&tlng=en This paper describes a few important aspects of the process that should be followed before an experiment is conducted. One should start by defining the hypothesis or theory to be tested, which gives a good indication of the way in which the experiment should be designed, and also informs of the way in which the data should be analysed. In order to ensure the success of a trial the number of replications, or animals, should be calculated beforehand, and if too few are possible, or available, then the experimental design should be changed to accommodate this. The approach to the design of response experiments differs from that when two or more independent treatments are being compared, in that fewer replications and more doses would be favoured. Also, it is worth extending the range of inputs beyond the conventionally-applied doses. This is because a response surface must be fitted to the data, and the more points and the wider the range the better for this purpose. Duncan's multiple range test is always inappropriate when analysing a dose/response experiment, and should never be used for this purpose. The optimum dose should be chosen on the basis of the hypothesis being tested, but should preferably include economic data such that an optimum economic dose can be determined, which could be modified as economic circumstances change. <![CDATA[<b>Environmental-genotype responses in livestock to global warming</b>: <b>a southern African perspective</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500003&lng=en&nrm=iso&tlng=en Global warming will change Southern Africa's environments from grass dominated vegetation to dry woodland and desert with a vegetation of C4 dominated grasses, whereas the grazing capacity is expected to decline by more than 30%. Animals will also be more exposed to parasites and diseases, mainly as a result of an increase in temperature. An improved understanding of the adaptation of livestock to their production environments is thus important, but the measurement of adaptation is complex and difficult. Proxy-indicators for adaptation, such as reproductive and production traits, can however be used. Adaptation can also be characterized indirectly by describing the production environment in which a breed or population has been kept over a period of time and to which it has become adapted. By describing production environments it will be possible to identify breeds or genotypes that may be adapted to the changed environment of an area. In respect of quantitative breeding technology, fixed and random effects that account for spatial and temporal variation in production environments will have to be identified and physiological breeding value estimations may be necessary. Tools will need to be developed to overlay geo-referenced data sets available onto the different production environments in order to quantify them. Gene or marker assisted selection may play an important role in selection for disease and parasite resistance or tolerance, since it is difficult to measure these traits directly. The development of a high-throughput SNP or gene chip (genomic selection based on Single Nucleotide Polymorphisms) may enhance the utilization of marker assisted selection. Recent research has indicated that the inclusion of information from DNA analysis into BLUP breeding values may result in substantial increases in genetic gain at reduced cost. Strategies that utilizes EBVs derived from genomic analyses (genomic EBVs), together with conventional mixed model methodology, may speed up the process of breeding animals that are adapted to the newly created environment as a result of global warming. <![CDATA[<b>Effect of environmental factors on the digestibility and voluntary feed intake of kikuyu</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500004&lng=en&nrm=iso&tlng=en Digestion trials using sheep and voluntary feed intake (VFI) trials using long yearling heifers in Calan gates were conducted in the spring, summer and autumn. Five years of digestibility data, amounting to 82 digestion trials, was pooled for this study. Voluntary intake data was pooled for the three years of intake trials, amounting to 38 intake trials. These data and the daily maximum temperatures, rainfall and evaporation recorded at and prior to the digestion and intake trials at Cedara were pooled, analysed using multiple regression techniques, and regressed on dry matter digestibilty and VFI, to examine the influence of environment on the nutritive value of the herbage and to develop simple linear regression models for predicting kikuyu quality and intake. Rainfall and temperature in the period of cutting (plot preparation) and fertilization had a negative effect on digestibility, irrespective of the stage of re-growth at harvesting, 20, 30 or 40 days later, and a combination of the two proved significant, accounting for the most variance in DMD. Temperature depressed DMD by 28.1 g/kg DM per degree rise in temperature (ºC). Temperatures recorded during the cutting and fertilization phase were highly negatively correlated to VFI, irrespective of stage of re-growth. <![CDATA[<b>Effect of herbage composition on the digestibility and voluntary feed intake of kikuyu</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500005&lng=en&nrm=iso&tlng=en Digestion trials using sheep and voluntary feed intake (VFI) trials using long yearling heifers in Calan gates were conducted in the spring, summer and autumn over 5 years. These data and the chemical composition of the herbage were regressed on DMD and VFI. Excluding the mineral fractions, only three of the chemical components of the herbage emerged as important, namely, the DM content of the herbage as fed, accounting for 32% of the variance in DMD, the NPN content of the herbage accounting for only 12.2% of the variance and the ash content of the herbage accounting for 15.9% of the variance in digestibility. Of the macro-mineral components, Ca, Mg and P tended to be positively associated with DMD, while Na and K were significantly related to DMD. NDF was positively correlated to VFI, accounting for 37% of the variability in intake, while non-protein nitrogen was negatively correlated to VFI, although it did not account for much of the variability (11%) in VFI. Ca was also positively correlated to VFI, also accounting for very little of the variation in VFI (11.7%). Herbage Mg had a positive influence on VFI, accounting for 24% of the variation in VFI. Both DMD and VFI were highly negatively influenced by the moisture content of the herbage. <![CDATA[<b>The economic viability of finishing Nguni weaners on natural veld and permanent pastures</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500006&lng=en&nrm=iso&tlng=en The objective of this study was to investigate the economic viability of finishing Nguni weaners on natural veld and permanent pastures under dry land conditions. A group of 30 Nguni calves (7-9 months age) were randomly divided into two treatment groups: a group on Eastern Province Thornveld (Veld group) and a group managed on Panicum maximum pastures. The average daily gain (ADG) of the weaners in the Pasture group (0.606 kg/day) during this period was significantly higher than weaners on natural veld (0.434 kg/day). The profit per weaner (margin above direct allocated costs) in the Veld group was R246.56 higher than that of calves in the Pasture group but the highest return per ha was obtained from weaners raised on permanent pastures. These findings suggest that it was still more economic viable to finish Nguni weaners on the more costly Panicum pastures than on natural Eastern Province Thornveld. <![CDATA[<b>Effect of two levels of supplementary feeding and two stocking rates of grazing ostriches on irrigated lucerne dry matter intake and production</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500007&lng=en&nrm=iso&tlng=en This study determined the effect of two stocking rates of ostriches (10 and 15 birds/ha) and two levels of supplementary feeding (0 and 800 g/bird/day) on the intake and production of irrigated lucerne pastures over a period of five months (January to May). A lucerne pasture was divided into 16 paddocks of approximately 0.85 ha each. One hundred and seventy ostriches (± 6 months old) were randomly allocated to four groups and four different lucerne paddocks were randomly allocated to each group. Each ostrich group rotationally grazed the four lucerne paddocks and was moved to a new paddock every two weeks or as soon as pasture became depleted. The available pasture dry matter was determined by cutting and collecting a 0.166 sq m size sample to ground level inside and outside exclosure cages placed inside each paddock every time the ostriches left a paddock. Pasture material were washed to remove soil and dirt and dried to a constant dry mass at 59 ºC. The data was analyzed with analysis of variance, using the four paddocks as replicates and with two treatments and two treatment levels. For lucerne intake a significant interaction was found between level of supplementary feeding and month. Intake was not significantly influenced by supplementary feeding during January, February, March and April, but during May lucerne dry matter intake was significantly higher at 0 g/bird/day than at 800 g/bird/day. This seems to indicate an increasing level of replacement of grazed lucerne dry matter by supplementary feeding as the trial progressed. This is supported by the fact that there tended to be an interaction between stocking rate and level of supplementary feeding in terms of lucerne dry matter intake. This resulted in lucerne dry matter intake being higher at 15 birds/ha than at 10 birds/ha at 0 g supplementary feeding/bird/day, while at 800 g supplementary feeding/bird/day there was no difference in lucerne dry matter intake. In the case of lucerne dry matter production a significant interaction was found between stocking rate and month. During January, February and March lucerne dry matter production was significantly higher at the 15 birds/ha stocking rate than at 10 birds/ha, while there was no difference in April and lucerne production was significantly higher at 10 than at 15 birds/ha in May. The high stocking rate of 15 birds/ha therefore seems to have had a gradual depressing effect on lucerne dry matter production. The less severe levels of defoliation at the low stocking rate possibly promoted lucerne dry matter production. It can be concluded that stocking rate, as well as level of supplementary feeding, influenced lucerne dry matter intake, but only stocking rate influenced lucerne production. Supplementary feeding depressed lucerne intake only at the high stocking rate. <![CDATA[<b>The response in food intake and reproductive parameters of breeding ostriches to increasing dietary energy</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500008&lng=en&nrm=iso&tlng=en Elucidating the factors affecting feed intake is important when quantifying nutrient responses in breeding ostriches. The experiment was conducted to determine to what extent dietary energy content will affect the important production parameters of breeding ostriches. Ninety pairs of breeding ostriches were divided into six groups, consisting of 15 breeding pairs per group. Six diets with increasing metabolisable energy content (8.0, 8.7, 9.4, 10.1, 10.8 and 11.5 MJ ME/kg feed) were provided ad libitum to birds during the breeding season. All the other nutrients were kept constant in all feeds. Responses were measured by simple linear regression. Average daily feed intake (3.7 ± 0.2 kg) was unaffected by energy content as were all the reproductive parameters measured, including total eggs produced per female (45.6 ± 5.8), number of chicks hatched (21.3 ± 4.5), number of infertile eggs (11.6 ± 3.6), number of dead-in-shell eggs (7.5 ± 1.8) and egg weight (1406 ± 31 g). However, the significant increase in live mass of both males and females indicated that energy was over-consumed as the energy content of the diet was increased. Breeding ostriches did not regulate feed intake according to dietary energy content but instead based their intake on the concentration of the limiting nutrient in the feed. <![CDATA[<b>Between male variation in semen characteristics and preliminary results on the dilution of semen in the ostrich</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500009&lng=en&nrm=iso&tlng=en This study is part of an ongoing project on artificial insemination in ostriches. The physical output of neat semen from four ostrich males was investigated and the effect of reconstituting semen with: 1) seminal plasma of the same male (SPS); 2) seminal plasma of another male (SPD), and 3) Dulbecco's Modified Eagles Medium (DMEM). Semen was collected daily from one or two pairs of males using the dummy female method, each pair being replicated twice. Spermatozoa viability in neat semen, SPS, SPD and DMEM was assessed using nigrosin-eosin staining and the proportions of live normal, live abnormal and dead sperm were determined. Semen volume (mean ± SE) was 1.27 ± 0.13 mL, the concentration of spermatozoa 3.68 ± 0.17 x 10(9) /mL and the number of spermatozoa 4.92 ± 0.64 x 10(9) /ejaculate. Furthermore, the live normal, live abnormal and dead spermatozoa in the neat semen were 61.2 ± 4.5%, 21.2 ± 2.7% and 17.7 ± 4.3% respectively. The ejaculate volume and the number of dead spermatozoa were not affected by collection time. However, the number of live abnormal spermatozoa increased through the day causing a reduction in live normal spermatozoa. Furthermore, re-suspending spermatozoa in DMEM reduced the number of live normal (31.4 ± 4.6%) and live abnormal spermatozoa (11.0 ± 2.7%) and increased the number of dead spermatozoa (57.6 ± 4.4%). In contrast, numbers of live spermatozoa were higher when suspended in seminal plasma and similar in SPS (53.9 ± 4.6%) and SPD (50.7 ± 4.6%). These are the first crucial steps to determining the optimum semen collection time and to improving the viability of diluted spermatozoa. <![CDATA[<b>Dietary manipulation of oil production in commercial emu</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500010&lng=en&nrm=iso&tlng=en The aim of this research was to optimize emu oil production by manipulation of the dietary protein and energy ratios for greater fat accretion. The research was done at African Emu Ranch in Muldersdrift, Gauteng. Twenty-four, four to five months old emu birds were randomly allocated to three dietary protein treatments, namely a standard control diet containing 170 g crude protein (CP) or a 140 and 200 CP/kg diet, all with similar metabolizable energy content. Proximate analyses were done on representative samples of the diets to confirm the nutrient composition based on AOAC techniques. Water and feed were given ad libitum. The feeding trial spanned eight weeks. The birds were slaughtered and fat yield, anatomical and histological parameters, volatile fatty acid production and carcass weights were recorded. The fat was analyzed for lipid content and composition by means of gas chromatography. Growth rates and average weight gains of the birds in different treatments did not differ. The average dressed out carcass weights for 140, 170 and 200 g CP/kg groups were 16.75, 18.65 and 19.11 kg respectively and differed between treatments. The 200 g CP diet yielded the heaviest carcasses and highest dressing percentage. Volatile fatty acid (VFA) concentrations did not differ between dietary treatments. Acetic acid was the most abundant volatile fatty acid in the distal and proximal intestines. The highest concentration of acetic acid was found in the distal ileum. A small volume of iso-butyric acid was detected in the distal ileum. Total average fat yields for the 140, 170 and 200 g CP groups were 4.1, 4.2 and 4.4 kg respectively, but fat yields did not differ between treatments. The long-chain fatty acid composition of the fat did not differ between treatment groups and consisted of saturated fatty acids (27.74%), monounsaturated fatty acids (51.80%), and polyunsaturated fatty acids (20.45%). Fatty acid composition did not differ between different anatomical fat depots in the carcass. The total mean of lipid produced in the omental and subcutaneous locations were 82% and 92.5% respectively. The results suggest that optimum emu oil production can be achieved by feeding diets with a low protein (optimum level of 140 g) to energy ratio. <![CDATA[<b>Embryo transfer using cryopreserved Boer goat blastocysts</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500011&lng=en&nrm=iso&tlng=en The aim of this trial was to evaluate the effect of embryo cryopreservation techniques on the survivability of embryos and fertility following transfer to Boer goat does. The oestrous cycles of 27 mature recipients Boer goat does were synchronised using controlled internal drug release dispensers (CIDR's) for 16 days. At CIDR removal, does were injected with 300 IU eCG. The recipient does were allocated to 3 groups (n = 9 per group), based on the technique of cryopreservation used for the embryos transferred. The in vivo produced embryos used were at blastocyst stage and surgically collected on day 6 following AI from Boer goat donors superovulated with pFSH. The first group received fresh embryos and served as the control, the second group of does received conventional slow frozen/thawed embryos and the third group received vitrified/thawed embryos. Two blastocysts were transferred per doe. A pregnancy rate of 85.7% (n = 6) was obtained following the transfer of fresh embryos and tended to be better than in does receiving slow frozen and vitrified embryos, (n = 4; 50.0% and n = 3; 37.5% does pregnant, respectively). The overall gestation period recorded for all does was 146.3 ± 3.0 d, with an overall litter size of 1.7 ± 0.5 being recorded. The kidding rate of the recipient does declined to 57.0% (4) and 25.0% (2) for fresh and conventional slow frozen groups, respectively. An embryo survival rate of 35.7% (n = 5) for fresh, 25.0% (n = 4) for conventional slow freezing and 31.3% (n = 5) for vitrification was recorded and was not affected by the number of CL's present on the respective ovaries at the time of transfer. There was a tendency for more females to be born than males (ratio 1 : 2, male : female) but this could not be related to the cryopreservation technique. Although the pregnancy rate following the transfer of fresh embryos was satisfactory, the embryo survival rate following the transfer of either fresh or cryopreserved embryos tended to be less acceptable. More research is warranted with larger numbers of animals, directed at improving the survivability of embryos following fresh and cryopreserved goat embryo transfer. <![CDATA[<b>Reproductive performance of semi-intensively kept Döhne Merino ewes fed with different protein supplements</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500012&lng=en&nrm=iso&tlng=en A trial was conducted to determine the possible effects of an easily digestible nitrogen source in the form of urea compared to an undegradable protein supplement, age and birth status on the reproductive performance (ovulation rate and rate of twinning) of ewes. The weight, age and birth status of Döhne Merino ewes were recorded. A total of 144 Döhne Merino ewes were randomly allocated in two dietary treatment groups (either urea-based or undegradable protein group) synchronised, mated and the ovulation rate (estimated from the number of corpora lutea on the ovaries), foetuses observed on day 55 of gestation, lambs born per ewe and mass of the ewe after lambing were recorded. Dietary protein supplement had no significant effect on ovulation rate, pregnancy status, the number of lambs born per ewe or ewe weight after lambing. The number of lambs born per ewe of the one-year-old (0.99 ± 0.316), two-year-old (1.23 ± 0.134) and seven year old (0.92 ± 0.305) ewes were lower than that of four (1.69 ± 0.222) and six-year-old ewes (1.897 ± 0.248). Ewe age did not influence the ovulation rate of ewes, but the highest number of foetuses counted on day 55 of gestation was observed in 3-year-old ewes (1.68 ± 0.196). The number of lambs born per ewe of single born ewes (1.23 ± 0.104) was lower than that of twin born ewes (1.62 ± 0.106). It was concluded that dietary protein supplementation had no significant effect on ovulation rate or the number of lambs born per ewe mated, while age and birth status influenced the reproductive rate of Döhne Merino ewes. <![CDATA[<b>Genetic trends in South African terminal sire sheep breeds</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500013&lng=en&nrm=iso&tlng=en Genetic trends were constructed for early growth traits in the Dormer and Ile de France terminal sire sheep breeds. The traits that were considered were birth weight, pre-weaning weight, weaning weight and post-weaning weight. However, pre-weaning weights were only available for the Ile de France breed and post-weaning weights were only available for the Dormer breed. Regressions of average annual breeding values on birth year indicated significant genetic gains in all early growth traits during the evaluation period. The average predicted direct breeding value of birth weight decreased by 0.055% per annum whereas weaning weight increased by 0.12% per annum and post-weaning weight improved by 0.32% per annum in the Dormer breed. The Ile de France registered an undesirable increase in the predicted direct breeding value of birth weight which amounted to 0.025% per annum. Predicted direct breeding values for pre-weaning weight increased at an annual rate of 0.23% and that of weaning weight by 1.21% per annum. Although adequate genetic variation for substantial genetic progress was available, only modest rates of progress were attained for all the traits in both breeds. The only possible exception was weaning weight in the Ile de France breed, which was improved at > 1% per annum. At least all changes were in the desired direction, barring the direct genetic trend for birth weight in the Ile de France breed. Breeders should be encouraged to record data consistently, as one of the major shortcomings in the data for both breeds were a lack of continuity in the submission of data to the NSIS. More informative analyses ought to be feasible if this requisite is met. <![CDATA[<b>The effect of age and gender on the fat distribution in Merino lambs</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500014&lng=en&nrm=iso&tlng=en The goal of this study was to determine the effect of gender on visceral and subcutaneous fat distribution of Merino lambs finished off under feedlot conditions. The diet (16% protein, 10MJ ME/kg feed) was fed ad libitum and animals had free access to water. A total of 108 lambs (58 wethers, 50 ewes) were divided into six groups. Groups of lambs were slaughtered every three weeks at respectively 90, 111, 132, 153, 174 and 195 days of age. The visceral fat was removed, weighed and expressed as a percentage of carcass mass, while the subcutaneous fat thickness was measured at the 13th rib. A growth curve was calculated for each gender, and the effect of age on the different fat parameters determined. The growth rates of male and female lambs did not differ and were respectively 45.2 g and 43.2 g per day. Age had a positive effect on % visceral fat with an increase of 0.029% for wethers and 0.032% for ewes per day. Similarly, fat thickness increased at a rate of 0.070 mm for wethers and 0.053 mm for ewes per day, indicating that gender had an influence on the rate of fat deposition. However, the inverse rate of deposition between the genders (visceral fat versus subcutaneous fat) warrants further discussion. <![CDATA[<b>A comparison of genetic diversity between South African conserved and field chicken populations using microsatellite markers</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500015&lng=en&nrm=iso&tlng=en The objective of the study was to determine genetic diversity within South African indigenous chicken populations and the effectiveness of the current conservation flocks in capturing the available diversity in the founder populations. Two chicken populations, Venda (VD_C) and Ovambo (OV_C) conservation flocks (n = 56) from the Animal Production Institute in Irene and two founder population from which these conservation flocks were sampled; Venda (VD_F) and Ovambo (OV_F) field populations (n = 72) were genotyped for 29 autosomal microsatellite markers. All microsatellites typed were found to be polymorphic. A total of 213 alleles were observed for all four populations. The mean number of alleles per population ranged from 3.52 ± 1.09 (VD_C) to 6.62 ± 3.38 (OV_F). Mean observed (H O) and expected (H E) heterozygosity in the conservation flocks were 0.55 and 0.57 respectively. The corresponding values for the founder population were 0.62 and 0.68. The observed within population diversity measures indicated that field populations are more diverse than conservation flocks. The Reynolds genetic distance (D Reynolds) between conservation flocks and field population observed was 0.22 between VD_C and VD_F and 0.09 between OV_C and OV_F. STRUCTURE was used to cluster individuals to 2 < K < 5. The most probable clustering was found in K = 3, in which the populations were grouped into three clusters. VD_C and OV_C conservation flocks separated as independent clusters, while VD_F and OV_F field populations formed one cluster for any K value. Clustering analysis indicated a clear subdivision of the conservation flocks and field population into genetically distinct populations. The present study suggests that conservation flocks are less diverse compared to field populations. <![CDATA[<b>An evaluation of ratios as a measure of carcass traits using mature indigenous chickens in Limpopo Province of South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500016&lng=en&nrm=iso&tlng=en Live weight and weight of body parts of 60 mature indigenous chickens were collected to investigate whether the use of ratios in poultry science may cause misinterpretation of data and misleading conclusions. Three villages from Mukula Tribal land in Thulamela municipality from Vhembe District in Limpopo Province of South Africa were identified for the purpose of this study. Five mature chickens were bought from each village, weighed, killed, dressed and cut to get the body parts using the standard procedures. This was done across the four distinct seasons from March 2005 to March 2006. The data was collected using a weighing scale with variables of interest being the sex, season and village. Summary statistics were computed and data was analyzed in two separate ways using the Statistical Analysis Software Packages as follows: Firstly each individual body part was expressed as ratio of body weight and data analyzed using a simple analysis of variance (ANOVA) procedure. Secondly, live body weight was used a covariate in the analysis of other body parts using the ANCOVA procedures. Ratios suggested differences gizzard, liver, head and feet and body length due to sex and in gizzard, liver and body length due to village which were not apparent with ANCOVA. The results from this study suggested that ratios did not remove the variation due to differences in sex and village and may lead us to wrong conclusions. From this study, one can draw conclusions that use of ANCOVA gives us the exceptional method for interpreting the data correctly. <![CDATA[<b>Boar effects and their relations to fertility and litter size in sows</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500017&lng=en&nrm=iso&tlng=en Twenty Large White boars and 60 sows were used in two experiments for this study. In experiment 1, 20 sows were assigned per group to each of three treatments, twice daily for a 30-min period during a 4-wk observation, involving: (1) NBE, a control in which sows were not exposed to boars during oestrus detection; (2) FBE, in which sows were exposed to fence-line boars during oestrus detection and (3) PBE, in which sows received physical contact with the boar during oestrus detection. In experiment 2, semen were collected at 24- or 96-h intervals from each boar and used (3.5 x 10(9) sperm/100 mL/sow) to artificially inseminate three oestrus-synchronised sows, 24 h after the onset of oestrus, for four weeks. Boar exposure for 4 d before oestrus induction (PG600) increased the proportion of sows expressing oestrus within 7 d by 44% with 88.3 ± 5.5% farrowing rate in the PBE group with the shortest interval from PG600 to oestrus (3.5 ± 0.2 d), number of returns to oestrus (0.01 ± 0.02) and farrowing-farrowing interval (136 ± 0.01 d). On average, 45.8 ± 2.5% of the control NBE group of the sows showed spontaneous oestrus compared to 56.3 ± 1.9 vs. 88.5 ± 0.7% of FBE and PBE groups, respectively. Ejaculates collected on the 96-h intervals had larger volumes (288 ± 9.3 vs. 124.9 ± 5.7 mL), sperm motility (87.1 ± 3.3 vs. 55.2 ± 0.9%) and type of movement (8.7 ± 0.5 vs. 3.0 ± 0.1), live sperm (78.3 ± 9.6 vs. 57.9 ± 12.6.), sperm/mL (132.6 ± 8.1 vs. 90. 4 ± 12.1 x10(6)), total sperm/ejaculate (83.2 ± 7.7 vs. 52.5 ± 4.6 x10(9)) and normal acrosome (92.5 ± 18.4 vs. 55.5 ± 15.6%) than ejaculates collected on the 24-h intervals. Semen collected at 96-h had gave higher non-return rate (93.5 ± 2.9 vs. 76.8 ± 5.2 %), farrowing rate (85.5 ± 14.3 vs. 56.8 ± 9.1%,), litter size (12 ± 0.03 vs. 8 ± 0.02) and live piglets were 30% higher compared with those from sows inseminated with semen collected at 24-h intervals, respectively. Results suggest that direct exposure of boars to sows prior to semen collection enhances oestrus expressions and farrowing rates. Secondly, ejaculating boars at 96-h intervals enhances semen quality and quantity leading to significant improvement in the fertility and litter size of artificially inseminated sows. <![CDATA[<b>The assessment of crystals derived from Aloe spp. for potential use as an herbal anthelmintic thereby indirectly controlling blowfly strike</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500018&lng=en&nrm=iso&tlng=en Dagginess predisposes sheep to breech strike and can be controlled with management practices (e.g. mulesing, crutching) or by treating the animal with an anthelmintic. The effect of regular treatment with crystals derived from Aloe spp as a natural anthelmintic was assessed in yearling Merino progeny born in 2004 (Trial 1) and 2005 (Trial 2), while the short-term effect of aloe treatment over 14 days was also considered (Trial 3). Animals were randomly allocated to a treatment group (aloe or distilled water). Natural challenge was used to ensure that all animals received an adequate gastro-intestinal nematode challenge, prior to being drenched with an aloe solution, or distilled water as a control treatment. Following treatment, gastro-intestinal nematode egg counts (FEC) were obtained at regular intervals to assess the effect of aloe treatment. Dag scores were also recorded prior to shearing as hoggets. The experimental outlay of all trials was factorial, with aloe treatment and sampling date as main effects. Recordings of FEC were subjected to a cube root transformation prior to analyses to normalise the distribution in all cases. When monthly FEC was considered in Trial 1 and 2, there was also no evidence of a reduced parasite burden in the treated group. No change was accordingly found in Trial 3, where the short-term effect of treatment was considered. The mean dag scores of individuals in Trials 1 and 2 were accordingly not affected by treatment with aloe. Alternative strategies for the reduction of FEC and flystrike thus need to be considered. <![CDATA[<b>Nutritionally-related blood metabolites and faecal egg counts in indigenous Nguni goats of South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500019&lng=en&nrm=iso&tlng=en The objective of the study was to determine the effect of season on faecal egg counts and biochemical profiles in indigenous Nguni goats of South Africa. Body weights, body condition scores, faecal and blood samples were collected from 96 goats. Faecal samples were analysed for nematodes and trematodes. Blood was analysed for packed cell volume (PCV), glucose, cholesterol, total protein, albumin, globulin, urea and creatinine. Significantly higher total protein and globulin values were recorded in the wet than the dry season. A significant positive correlation was recorded between body condition scores and albumin concentrations. Season had an effect on glucose, globulin, TP, creatinine, PCV and FEC of Nguni goats. It, therefore, is imperative to put measures in place to counteract the drop in any of these parameters, with season, if productivity of the indigenous goats is to be maintained. Further studies are required to determine the parasites causing chronic health challenges that were evidenced by elevated globulin concentrations in the flock studied. Since the high globulin levels were not accompanied by clinical cases, the reference levels used might be inappropriate for the indigenous Nguni goats. <![CDATA[<b>Effect of sun drying on microbes in non-conventional agricultural by-products</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500020&lng=en&nrm=iso&tlng=en There is concern whether cabbage and beetroot wastes from the Fresh Produce Market are safe for feeding animals given the fact that some will have been discarded at the onset of putrefaction. This study evaluated the effects of sun-drying on microbiological load (E. coli, coliform, yeast and moulds and total bacterial count) in waste vegetables from the fresh produce market, since smallholder farmers tend to use the by-products without processing given the opportunity. Cabbage and beetroot wastes were sun dried to 14% moisture and micro-organisms were enumerated on both wet and dried samples. The results showed that sun drying reduced the level of micro-organisms significantly in both cabbage and beetroot. Although microbial load varied from batch to batch in the wet samples, coliforms were significantly more abundant in wet beetroot than in the dried samples. However, dried beetroot contained significantly more yeast and moulds. Wet cabbage contained more coliform and yeast and moulds compared to sun-dried cabbage. The sun drying process is thus an efficient processing method for resource poor farmers to reduce the microbial load in these animal feed sources and improve their shelf life. <![CDATA[<b>Evaluation of potato hash silage from two bacterial inoculants and their effects on the growth performance of grower pigs</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500021&lng=en&nrm=iso&tlng=en Potato hash was mixed with wheat bran at 7:3 ratio, treated with homofermentative LAB inoculant (BMF, bonsilage forte), heterofermentative lactic acid bacteria (LAB) (LFLB, Lalsil Fresh LB) and without LAB inoculant and ensiled in 210 L drums for 90 days. After 90 days of ensiling, concentrates that contained 40% potato hash silage (PHS) were formulated and the treatment groups were control (no silage), untreated PHS, BMF treated PHS and LFLB treated PHS. The diets were fed to 64 growing pigs (60 days old and 30.4 ± 2.3 kg body mass). The pigs were allocated in a complete randomized block design with four treatments, and each treatment consisted of eight boars and eight sows. Pigs were fed ad libitum, feed intake was measured daily while body masses were recorded at the start and weekly throughout the experimental period. The dry matter intake (DMI) was higher in the control diet (1062 g/kg) than in the untreated PHS diets (933 g/kg), BMF treated PHS (873 g/kg) and LFLB treated PHS (919 g/kg) diets, respectively. Pigs in the control group had higher final body weight (60.77 kg), average daily gain (ADG) (551 g/d) and better feed conversion rate (FCR) (4.92 g/g) at the end of the trial compared to those in other treatment groups. It can be concluded that potato hash silage produced with or without LAB inoculants had the same effect on the growth performance of growing pigs. However, further work is needed to evaluate the effects of higher dietary inclusion levels (>40 %) of ensiled potato hash on pig growth and reproductive performance. <![CDATA[<b>Effects of sun-dried <i>Opuntia ficus-indica</i> on feed and water intake and excretion of urine and faeces by Dorper sheep</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500022&lng=en&nrm=iso&tlng=en The effects of incremental levels (0, 24 and 36%) of sun-dried and coarsely ground Opuntia cladodes in balanced diets on feed and water intake and excretion of urine and faeces were investigated. Nine Dorper wethers (mean live weight 45.3 ± 1.9 kg) were stratified according to body weight in three treatment groups and a diet randomly allocated to each group. The wethers were housed indoors in individual metabolic cages and fed the diets during a 7-day trial period. Feed and water intake and urine and faeces excretions were monitored and sampled for chemical analysis. The daily intake of feed (1096.3 ± 84.8, 1295.6 ± 80.9 and 1086.9 ± 95.8 g/day) and water (1993.3 ± 75.1, 2430.5 ± 265.3, 2295.2 ± 273.8 mL/day) for diets T0, T24 and T36 respectively, were not significantly influenced by including sun-dried Opuntia cladodes. Daily urine excretion showed no significant differences between treatments T0, T24 and T36. Inclusion of Opuntia cladodes in the diets resulted in the production of wet faeces within days, due to the presence of mucilage. Despite aesthetical aspects no detrimental effects were noted in the sheep. On the contrary, diet T36 had a significantly higher digestibility than diet T0, particularly for DM (digestibility coefficients = 0.723 ± 0.01 and 0.653 ± 0.01, respectively) and excreted less faecal DM (250.0 ± 21.1 vs. 345.2 ± 20.1 g/day). <![CDATA[<b>Palatibility of <i>Opuntia</i> varieties available in South Africa for dryland sheep</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500023&lng=en&nrm=iso&tlng=en Opuntia is generally recognized as a fruit crop for semi-arid, subtropical conditions around the world. The majority of Opuntia plant biomass is palatable and is a cladode material rather than fruits which can be fed to livestock. An experiment was conducted on the Roodeplaat Experimental farm, situated north east of Pretoria, South Africa. Forty two Opuntia varieties were fed fresh to evaluate their palatability to dryland sheep. The experiment consisted of four Pedi sheep blocked according to weight in five camps containing three feeding troughs, where three different varieties were fed randomly on a daily basis. Each Variety was presented in a different camp in a different combination for five days. All varieties, except for Rubusta, were palatable and intake varied between 11.3 kg and 13.4 kg for the four sheep. The dry matter, crude protein-, ether extract, TNC and WSC of the different varieties were determined, but could not be linked to palatability. Big differences in yield were found between different varieties. Recommendations on further research regarding Opuntia are made in the paper. <![CDATA[<b>Growth performance of feedlot weaners cattle fed diet containing different levels of cold press soya bean oilcake</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500024&lng=en&nrm=iso&tlng=en The value of cold press soya bean oil cake (CPSBOC) as the source of protein in beef cattle was evaluated. CPSBOC was included in the diets of beef weaners at different levels i.e. 0%, 6%, 13% and 20%. The control diet contained cotton seed oil cake (CSOC) as a protein source. The diets were formulated to be isonitrogenous. A total of 40 weaners (20 heifers and 20 steers) at an average weight of 192.3 ± 20 kg were used. The experiment was a randomized block design with ten replicates per treatment and was conducted over 98 days. The group mass of the steers (700 ± 7.80 kg) was significantly heavier when compared with the heifers (6480 ± 7.80 kg). The average daily gain (ADG) (1.5 ± 2.72) and feed conversion ratio (FCR) (5.5 ± 0.051) of the steers was significantly better than the heifers (1.35 ± 2.72 and 5.7 ± 0.051, respectively) while the steers consume more feed (8.2 ± 14.4 kg) per day as compared to the 7.4 ± 14.4 kg consumed by heifers. The weaners that were fed the diet containing 6% and 13% inclusion of CPSBOC grew significantly better than the other treatments. According to this study, an inclusion level of CPSBOC of between 6 and 13% will yield suitable growth in feedlot cattle. More research is needed to determine the optimum inclusion level of CPSBOC. <![CDATA[<b>The conversion of dopamine to epinephrine and nor-epinephrine is breed dependent</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892010000500025&lng=en&nrm=iso&tlng=en In previous reports, Nguni type cattle have shown to have a lower glycolytic potential with less glycogen measured in muscles 1 h post-mortem. With the release of catecholamines in the immediate pre-slaughter period, there is potential for depletion of muscle glycogen, because of the fact that epinephrine activates muscle adenylate cyclase and thereby stimulates glycogen breakdown. Epinephrine and nor-epinephrine are secreted as a result of any "fight or flight" situation. Tyrosine is a conditionally non-essential large neutral amino acid and the precursor of the neurotransmitters dopamine, nor-epinephrine and epinephrine. Ante-mortem stress experienced by an animal may be influenced by amino acids that provide substrates for neurotransmitter synthesis. The Nguni type cattle showed 55.8% and 55.1% greater urinary nor-epinephrine values than for the Brahman- and Simmental type cattle respectively. The Nguni type cattle showed 35.6% and 43.8% greater urinary epinephrine values than the Brahman- and Simmental type cattle respectively. The higher urinary nor-epinephrine and epinephrine levels measured in Nguni type cattle could either be explained by a greater neuronal out flux immediately prior to slaughter or a slower re-uptake.