Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 44 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>The influence of boar breed and season on semen parameters</b>]]> The aim of the present study was to demonstrate the influence of boar breed and season on semen parameters. The research material consisted of 31 boars: Polish Large White (PLW), Polish Landrace (PL), and Duroc x Pietrain (D x P), aged 8 to 24 months. The analysed material consisted of 1390 ejaculates, collected during the period January 2010 to October 2012. Semen samples were assessed in terms of semen volume (mL), sperm concentration (x 10(6) m/mL), total number of sperm (x 10(9)), total number of live sperm (x 10(9)) and number of insemination doses obtained from one ejaculate (n). In winter, an increase in sperm concentration was observed for the PLW breed. Moreover, an increase in the volume of semen produced for this breed was noted in summer and autumn. Differences between breeds for the total number of sperm and total number of live sperm were observed for the winter and spring periods. The largest semen volume was noted for the PLW breed (276.4 ± 9.66 mL). However, in the analysis of other sperm parameters, boars of this breed demonstrated the poorest results. The highest insemination dose was obtained from breed D x P in winter (26.0 ± 0.51). Correlation analyses indicated that PLW and D x P boars are the least resistant to higher ambient temperatures, and in summer and autumn this resulted in a reduction in sperm concentration (-0.26 and -0.20, respectively). <![CDATA[<b>Blood metabolite concentrations and postpartum resumption of ovarian cyclicity in Sanga cows</b>]]> An experiment was conducted to investigate the effect of concentrations of certain blood nutrient-sensitive metabolites and the resumption of postpartum ovarian cyclicity in 16 Sanga cows (mean BCS 5). Blood samples were taken from cows from weeks 1 to 13 (90 days) postpartum, processed and the plasma progesterone concentration measured to determine the resumption of postpartum ovarian cyclicity. The cows were classified as having resumed ovarian cyclicity when a plasma progesterone concentration of ≥1.0 ng/mL was recorded for two consecutive weekly samples. Based on the resumption of ovarian activity, cows were classified as early cycling, late cycling or non-cycling. The plasma glucose, cholesterol, total protein, albumin and globulin concentrations recorded were similar in the early cycling, late cycling and non-cycling cows. The mean blood glucose, cholesterol, total protein, albumin and globulin concentrations were 3.60 mmol/L, 2.47 mmol/L, 83.1 g/L, 29.9 g/L and 52.9 g/L, respectively. Plasma urea concentrations in late (6.57 ± 0.17 mmol/L) and non-cycling (6.59 ± 0.17 mmol/L) cows were higher than in the early cycling (5.99 ± 0.17 mmol/L) cows in weeks 1 to 13 postpartum. In addition, the plasma creatinine concentration in the early cycling cows was higher than in late cycling cows (101.8 ± 1.82 versus 94.0 ± 1.99 mmol/L). Cows with higher plasma concentrations of urea and lower creatinine concentrations were at risk of delayed resumption of postpartum ovarian cyclicity. Results suggest poor nutritional status, especially energy deficiency, as a major underlying factor suppressing the postpartum resumption of ovarian cyclicity. <![CDATA[<b>Effect of L-carnitine supplementation on drake semen quality</b>]]> This study was conducted to determine the effect on semen quality traits of supplementing the diets of Iraqi drakes with L-carnitine. Forty eight male Iraqi ducks, 30 weeks old, were randomly allocated to four treatments with 12 drakes per treatment group, replicated three times, with four drakes per replicate. The treatment groups consisted of birds fed a diet free of L-carnitine (T1, control group); birds fed a diet containing 50 mg L-carnitine/kg diet (T2); birds fed a diet containing 100 mg L-carnitine/kg diet (T3); and birds fed a diet containing 150 mg L-carnitine/kg diet. The drakes were fed the experimental diets only during the experimental period, which lasted three months. The semen quality traits that were investigated were ejaculate volume, mass and individual motility of spermatozoa, spermatocrit, spermatozoa concentration, percentages of dead and abnormal spermatozoa and acrosomal abnormalities. Supplementing the diet of drakes with L-carnitine at the levels of 50 - 150 mg/kg diet significantly increased ejaculate volume, spermatocrit, mass and individual motility of spermatozoa, and concentration of spermatozoa, while percentages of dead and abnormal spermatozoa and acrosomal abnormalities were decreased. However, T4 (150 mg L-carnitine/kg diet) recorded the best results in relation to all semen quality traits included in this study. Dietary supplementation with L-carnitine improved the semen quality of local drakes; therefore L-carnitine can be used as an efficient feed additive to improve the reproductive performance of male ducks. <![CDATA[<b>Seasonal variation in semen quality of Dorper rams using different collection techniques</b>]]> The aim of the study was to evaluate the seasonal variation in semen quality of Dorper rams using different semen collection techniques. The study was carried out from January 2012 to January 2013. A general management programme for health control was followed, with water being provided ad libitum throughout the trial, and all rams being fed a 2.5 kg maintenance diet per day. Eleven mature Dorper rams, recording a mean body weight of 69.6 ± 9.2 kg and mean age of 18 ± 4.7 months, were used in the trial. A group of six rams were trained for semen collection with the aid of the artificial vagina (AV), while in the remaining five rams, semen was collected using the electro ejaculator (EE). Immediately after collection, ejaculates were evaluated macroscopically and microscopically for semen volume, semen colour, semen pH, semen wave motion, sperm motility, sperm cell concentration, sperm viability and morphology. The results of the trial generally showed that semen in Dorper rams may be collected using the AV or EE methods throughout the year. However, an overall significant better semen quality collected by the AV versus the EE collection method was recorded. Generally, semen of significantly higher quality was recorded in summer, autumn and spring (both collection techniques). The tendency in the current trial was that the EE technique of semen collection was the less reliable method. Consequently the AV is recommended as the more acceptable method of semen collection in the Dorper. Winter is not generally recommended for semen collection, especially when using the EE. <![CDATA[<b>Chemical features, cholesterol and energy content of table hen eggs from conventional and alternative farming systems</b>]]> This study was carried out to investigate the effect of conventional farming systems for laying hens (standard cage batteries) and new alternative systems (improved cages and free range), approved by European Union (EU) poultry welfare legislation, on the chemical and nutritional quality of table eggs. The biological material consisted of eggs laid by 1200 Lohmann Brown hens, aged 27 weeks, fed similarly (a corn-wheat-soymeal diet). Conventional AOAC methods were used to analyse the eggs, and gross energy was calculated based on organic matter energy. All data were subjected to ANOVA statistical computation. The eggs produced in conventional cages compared with those laid in free-range farming conditions, presented significantly higher concentrations of total lipids (11.40 ± 0.65 g/100 g vs. 10.78 ± 0.87 g/100 g), cholesterol (211 ± 6.31 µg/egg vs. 202 ± 7.79 µg/60 g egg) and gross energy (0.36 ± 0.007 MJ/egg vs. 0.35 ± 0.012 MJ/egg). Consequently, it could be stated that under similar dietary conditions, the cage-free system influenced hens to produce eggs with a higher nutritive value than in the other systems. <![CDATA[<b>Non-genetic factors affecting fertility traits in South African Holstein cows</b>]]> Profitable milk production and genetic improvement in dairy herds depend largely on fertile cows calving annually to initiate a new lactation period. Over the last 30 years, several studies have indicated a decline in the reproductive performance of dairy cows. From the perspectives of many farmers and veterinarians, the reproductive performance of cows is related to the calving interval (CI) and services per conception (SPC). Using these traits as cow fertility indicators is problematic as CI is dependent on subsequent calving dates, while SPC is strongly linked to inseminator proficiency. Cow fertility refers to the ability of cows to come into oestrus soon after calving, to conceive from a minimum number of services, and to stay pregnant until the next calving. In this paper, non-genetic factors affecting fertility traits other than CI in Holstein cows are discussed. Service records (n = 69 181) and pregnancy check results of 9 046 cows in 14 herds were available. Six fertility traits were derived. Means (± sd) for the interval traits, namely calving to first insemination (CFS) and the interval from calving to conception (days open (DO)) were 77 ± 30 and 134 ± 74 days, respectively, while the number of SPC was 2.55 ± 1.79. The proportion of first services occurring within 80 days post partum (FS80d) and the proportion of cows being confirmed pregnant within 100 days (PD100d) and 200 days post partum (PD200d) were 0.64 ± 0.48, 0.36 ± 0.48 and 0.71 ± 0.45, respectively. While lactation number, calving year and calving season affected reproduction traits significantly, herds (management) had the largest effect <![CDATA[<b>Effect of feeding Moringa <i>(Moringa oleifera)</i> leaf meal on the physico-chemical characteristics and sensory properties of goat meat</b>]]> The objective of this study was to determine the physico-chemical characteristics and consumer sensory scores of chevon from crossbred Xhosa lop-eared goats supplemented with Moringa oleifera leaf meal (MOL). Twenty-four goats, aged 8 months, were divided into three groups with eight goats in each. All three groups were fed a basal diet of grass hay (GH) ad libitum and wheat bran at 200 g/head/day. In addition to the basal diet, the MOL and sunflower seed cake (SC) groups were fed 200 g dried M. oleifera leaf meal and 170 g sunflower seed cake, which contained 238 g and 233 g crude protein/kg, respectively, with GH having 141 g. Diet influenced chevon colour. Chevon from MOL- and SC-fed goats had higher values for lightness (L*) 24 h post mortem. The redness (a*) values of chevon 24 hours post mortem were significantly higher in MOL supplemented goats. Warner Bratzler shear force (WBSF) values of chevon from SC (30.1 N) and MOL (29.8 N) were lower than those for meat from GH diet (32.6 N). Chevon from goats fed GH diet had significantly higher cooking losses (29.5%) than that from the MOL (25.4%) and SC (25.6%) fed groups. Diet influenced the consumer sensory scores of chevon from goats supplemented with MOL, which had higher first bite, aroma, flavour and juiciness scores. Supplementing crossbred Xhosa lop-eared goats with an MOL diet produced chevon with the highest physico-chemical characteristics and consumer sensory scores. <![CDATA[<b>Different levels of macadamia oil cake meal, and wood ash vs. feed lime as dietary sources of calcium on bone characteristics of slow-growing chickens</b>]]> A study was conducted to evaluate the potential of macadamia oil cake meal (MOCM) and wood ash as feed ingredients for poultry under subsistence farming conditions. In this article, the effect of these ingredients on bone characteristics is reported. Two hundred and eighty eight day-old New Hampshire chickens were used in the study. The research was conducted as a 3 x 2 factorial design, and 48 chicks were randomly allocated per treatment. Three basic diets were formulated: one without MOCM and the other two containing 10% and 50% MOCM. The MOCM contained 132 g/kg of crude protein, 228 g/kg crude fat and 365 g/kg crude fibre on an 'as-fed' basis. Each of these three treatments was split into two: one receiving feed lime (CaCO3) as the main source of calcium; and the other wood ash, which contained 257 g Ca/kg. All diets contained a Ca level of ca. 10 g/kg. The chickens received the experimental diets from 2 to 15 weeks of age. After week 15, eight chickens per treatment were killed and their right legs removed at the femorotibial articulation and frozen for later evaluation. Between Ca sources there were no significant differences in tibia weight, diameter, volume, density and breaking strength. The ash content and Ca, P and Mg concentrations in bone ash between Ca sources were similar. However, in the two Ca diets containing 50% MOCM the Ca and P concentrations of the tibiae were significantly lower than in the diets containing lower levels of MOCM. It was concluded that wood ash was as effective as feed lime in supplying Ca to chickens. However, some practical problems in the feeding of wood ash became apparent, such as that wood ash is a fine powder and does not mix well with other ingredients, except when the oil content of the diet is high, as with the treatments containing MOCM. <![CDATA[<b>A study on gastrointestinal tract characteristics of ram lambs at the same weights from six Turkish sheep breeds</b>]]> A study was conducted, first, to compare the gastrointestinal tract (GIT), reticulo-rumens and intestinal capacities (relative to body weight) of ram lambs from six Turkish sheep breeds: Turkish Merino (TM, Anatolia Merino), Akkaraman (AK), Kıvırcık (KV), Awassi (AW), Karayaka (KY) and Morkaraman (MK), and second, to examine the influence of sheep breed on the pH of the digesta in the various segments (rumen, jejunum and caecum) of the GIT. Six ram lambs from each breed were slaughtered at 40.2 ± 0.80 kg liveweight. Lambs from the AK breed had a heavier GIT weight than the AW, KY or MK breeds. The weight of the full stomach was higher in AK lambs compared with the other lambs, except for KV lambs, while the relative weight of the empty stomachs was heavier in MK ram lambs than in TM, AW and KY lambs. The AK lambs had the highest relative empty intestinal weight. The relative weight of empty intestines was heavier in KV lambs than in KY lambs. The pH of the rumen content was higher in TM and AK lambs compared with KY and MK lambs, while the pH of the caecum content of KV lambs was higher than those of KY and MK lambs. In conclusion, significant differences were found among the six breeds in terms of some variables that were studied, although a higher proportional GIT weight in the fat-tail breeds such as the MK, AK and AW was not reflected in all components or in the pH of the GIT content. <![CDATA[<b>The Tankwa Karoo National Park feral goat population: A unique genetic resource</b>]]> The feral goats from Tankwa Karoo National Park in the Northern Cape, South Africa, constitute a potentially unique goat population, which dates back to the early 1900s, but is now at risk of extinction. A total of 66 feral goats from Tankwa Park and former Tankwa goats, now kept on a private farm were genotyped, using eight microsatellite markers. The data were compared with genotypic data of selected commercial breeds (Angora, Boer and Saanen dairy goats). Analysis of population structure using Bayesian and frequency-based methods suggests some uniqueness in the Tankwa populations. This uniqueness may reflect decades of random drift, but could also reflect alleles for adaptation to a harsh environment resulting from natural selection. These results are the first for the Tankwa goat and provide essential information for compiling a strategy for conservation and breeding of this genetic resource. <![CDATA[<b>Effect of polymorphism in the LIF gene on reproductive performance of hybrid Polish Large White and Polish Landrace sows</b>]]> The aim of the study was to determine the potential relationships between variants of the leukaemia inhibitory factor (LIF) gene and litter size in Landrace x Polish White sows. To identify polymorphisms within the LIF gene, the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was applied, using specific primers and the DralII enzyme. The researchers identified the presence of two alleles, T and C, with frequencies 0.64 and 0.36, giving three genotypes with frequencies of 0.44, 0.41 and 0.15, respectively, for TT, CT and CC. Analysis of relationships among the various genotypes of the LIF gene and selected reproductive traits showed differences. Sows with genotypes TT and TC in the LIF locus gave birth and raised significantly more live piglets in the first litter compared with sows with the CC genotype. <![CDATA[<b>Variation in individual piglet birth weights in a Large White </b><b>χ</b><b> Landrace sow herd</b>]]> Within-litter birth weight variation in pigs is increasingly becoming important in influencing the profitability of pig enterprises. The objective of the study was to characterize within-litter birth weight variation in piglets from Large White χ Landrace sows. The study was conducted using records from 1 768 litters collected between January 1998 and September 2010 from a pig herd in South Africa. The number of piglets born alive (NBA) ranged from three to 18. The mean within-litter birth weight coefficient of variation (CVBWT) was 17.6% and ranged from 0.47% to 50.7%. The distribution of CVBWT in the herd was positively skewed. CVBWT increased as NBA increased. Multiparous sows farrowed litters with higher CVBWT than gilts. To enhance profitability of pig enterprises, the selection for increased NBA should be followed by selection for decreased CVBWT. <![CDATA[<b>Evaluation of genetic trends for traits of economic importance in South African Holstein cattle</b>]]> Genetic evaluation for the South African dairy industry has kept pace with global advances in statistical methodology. Increasingly accurate estimated breeding values (EBVs), produced routinely in the past two or three decades, have aided selection decisions. This has been coupled with an increase in the number of traits officially recorded and for which EBVs are calculated. Currently, EBVs are routinely published for more than 20 traits for the major dairy breeds. The current study was conducted to assess the genetic trends realized for traits of economic importance in the South African Holstein population, for the period from 1983 to 2008. Performance and pedigree data of 1 231 930 animals were used to calculate EBVs for these traits by a multi-trait animal model. The resulting EBVs in turn were used to compute annual mean rates of genetic change. Genetic trends for yield decreased by approximately 57% during the decade from 1990 to 2000 and reached stasis in 2005 - 2007. Calving interval and somatic cell count also deteriorated over much or all of the period investigated. Given the widespread availability of genetic evaluations for these traits and the noted potential for selection to implement favourable genetic trends, development of strategies to improve the South African Holstein appears to be urgently needed.