Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 43 num. 2 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Genetic parameters for production traits and somatic cell score of the SA Dairy Swiss population</b>]]> The SA Dairy Swiss population could not previously be incorporated into the National Dairy Genetic Evaluation System, owing to inadequate population numbers and data structures. However, in recent years participation in Milk Recording has improved sufficiently to allow for genetic evaluation of the population. The aim of the study was therefore to estimate genetic parameters for the SA Dairy Swiss for production traits and somatic cell score in order to estimate breeding values routinely from the National Dairy Genetic Evaluation System. After editing procedures, a dataset of 25 621 test-day records for milk, butterfat and protein yields and a dataset of 10 438 test-day records for somatic cell count were obtained for further analysis. (Co)variance components for milk (kg), butterfat and protein yields (kg), as well as for somatic cell score, were estimated using a fixed regression multi-lactation animal model, based on test-day records of the first three lactations. Records from the various lactations were included as repeated measures. A multi-trait evaluation was performed for the production traits, while a single trait evaluation was done for somatic cell score, using the software package VCE4. Heritability estimates were 0.19 for milk, 0.16 for butterfat, and 0.16 for protein yields. The heritability estimate for somatic cell score was lower, at 0.07. The genetic correlations between the production traits were lowest for milk and butterfat (0.83), and were similar for milk and protein (0.94) and butterfat and protein yields (0.94). These values compare favourably with those of the other South African dairy breeds, based on the same model. The (co)variances were then implemented for estimation of breeding values for the SA Dairy Swiss population. Genetic trends were favourable for milk production traits with milk yield, butterfat and protein yields increasing by 25.13 kg/year, 0.96 kg/year and 0.79 kg/year, respectively; while the trend for somatic cell score was unfavourable, increasing by 0.86 units/year, since 1983. The SA Dairy Swiss could therefore be incorporated into the National Dairy Genetic Evaluation System of South Africa, using these covariance components and model. <![CDATA[<b>Carcass properties, chemical content and fatty acid composition of the <i>musculus longissimus</i> of different pig genotypes</b>]]> The aim of this study was to examine carcass properties and variability in chemical content and fatty acid composition in the musculus longissimus lumborum et thoracis (MLLT) of different genotypes of pigs. Of 36 male castrated animals used in the trial, 24 were from two strains of Mangalitsa pigs (12 Swallow -bellied (SBM) and 12 White (WM)), while 12 were of the Swedish Landrace (SL) breed (the most abundant meat/fattening breed in Serbia). The warm and cold carcass weights at slaughter were significantly higher in the WM and SL compared with the SBM. Results showed differences in warm and cold carcass dressing percentage between the groups. The SBM had significant lower values than WM and SL pigs. The total fat content was higher in WM and SBM pigs than SL pigs. The SL pigs had a significant higher percentage of water in their MLLT than the SBM and WM pigs. The representative of pig meat breeds, SL, contained significantly less cholesterol in its MLLT compared with the SBM and WM (-15.23% and -15.84%). However, differences in the content of saturated and unsaturated fatty acids were more expressed and distinct. A higher percentage of saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) were present in MLTT originating from SL pigs compared with the two Mangalitsa strains. The total monounsaturated fatty acids (MUFA) content was higher in SBM and WM than in SL pigs. The alpha linolenic acid concentration (C18:3 n-3) was significantly higher in SBM than in WM and SL pigs. <![CDATA[<b>Crossbreeding to increase beef production</b>: <b>additive and non-additive effects on weight traits</b>]]> Using breed differences effectively facilitates high productivity and profitability. Thus, the objective of the study was to estimate direct and maternal additive and heterosis effects for growth traits (birth weight, weaning weight, 19-month weight of heifers and cow weight) from five purebred and 24 crossbred breed types. Afrikaner (A), Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S) were evaluated as purebreds and as sire breeds on A and F1 BA, CA, HA and SA females. Breed additive effects were expressed as deviations from A. Effects of intra-breed genetic trend were assumed to be zero throughout. Solutions for the breed additive and heterosis effects were used to predict performance of the crossbred breed types to verify the adequacy of the genetic model. Correlations of observed and predicted means ranged from 0.87 for weaning weight to 0.94 for 19-month weight. Breed direct effects were consistently greatest for C and least for A across all traits, and maternal effects were greatest for S (except for 19-month weight) and least for C. Direct and maternal heterosis, on average, were positive for all weights. The indicus x sanga and indicus x taurus direct heterosis effects on all weight traits were greater than either the taurus x sanga or taurus x taurus effects, whereas the indicus x sanga maternal heterosis effect was consistently less than the estimated taurus x sanga maternal heterosis effect. <![CDATA[<b>Effect of crude glycerol from South African biodiesel production on growth, carcass characteristics and pork quality of pigs</b>]]> A study was carried out to evaluate the effects of dietary inclusion of crude glycerol as a partial replacement of maize at 50 g/kg and 100 g/kg in pig grower diets. Three experimental diets were formulated, a control (CN) and two diets containing 50 g/kg (low glycerol (LG)) and 100 g/kg (high glycerol (HG)) glycerol. The experimental diets were fed in a growth and carcass evaluation study to 60 Large White crossbred pigs (30 males and 30 females) weighing 21 ± 1.6 kg. There were no differences between the glycerol inclusion levels in daily gain, feed intake and feed conversion ratio and carcass traits of the pigs. Gilts had a higher dressing percentage and lower backfat thickness than boars. They also had shorter carcasses and a lower drip loss percentage than boars. There were no differences in thawing, drip, evaporation and total cooking losses of pork loin chops between treatments. It was concluded that crude glycerol can be included up to 100 g/kg in grower pig diets without any negative effects on pig performance. <![CDATA[<b>Germination as a processing technique for soybeans in small-scale farming</b>]]> Heat processing is an effective way of reducing antinutritional factors (ANFs) in legumes, but requires expensive facilities and equipment. Accurate control of temperature is critical to avoid under- or overheating. Therefore, heat treatment of soybeans is not a viable option for the average small-scale farmer in remote areas. Germination and other traditional methods, namely soaking and dehulling, were evaluated as alternative processing methods for soybeans. The effect of the processing treatment on the level of different ANFs, nutritional composition and in vitro protein digestibility (IVPD) of soybean seeds was determined. Soybeans were soaked for 24 hours and allowed to germinate for one to six days. Soaked soybeans were manually dehulled. Changes within seeds were noted for nutritional and ANFs during germination. Crude protein and fat content increased with increasing number of days germinated, but germination caused a decrease in starch content. Dehulling also increased the crude protein and fat content of the seeds. All treatments caused a significant decrease in condensed tannins of the soybeans. Trypsin inhibitor levels were numerically lower after germinating, soaking and dehulling of seeds, but not significantly so. There were no changes in IVPD after treatment of the soybeans. It was concluded that germination for a period of three days effectively improved the nutritional value of soybeans and can be considered an alternative treatment of soybeans for the small-scale farmer where heat treatment is impractical or impossible. <![CDATA[<b>The <i>PRNP</i> gene polymorphism in Rough-coated Pomeranian Landrace sheep</b>]]> Prion protein (PrP) is a membrane glycoprotein whose abnormal form is believed to cause a group of disorders known as transmissible spongiform encephalopathies (TSEs), which affect the brain and nervous system of both human beings and animals. The most familiar TSEs are Creutzfeldt-Jakob Disease (CJD) in human beings, and bovine spongiform encephalopathy (BSE) and scrapie in sheep and goats. It is well established that resistance or susceptibility to scrapie has a genetic background that is closely linked to amino acid variations within PrP at positions 136 (A/V), 154 (R/H) and 171 (Q/R). The ARR (alanine at codon 136 and arginine at codons 154 and 171) allele is associated with the highest resistance to scrapie, whereas the VRQ allele is linked to the highest susceptibility. In the present study the allelic and genotypic frequencies of the PRNP gene in the Rough-coated Pomeranian Landrace (RPL) were determined. Polymorphisms at codons 136, 154 and 171 were identified with the PCR-RFLP method. Of the eight observed genotypes, ARR/ARQ (35.9%) and ARQ/ARQ (24.4%) were the most frequent. This study reported a presence of AHQ/AHR genotype (2.6%) that has not previously been recorded in any sheep breed. The predominance of wild-type ARQ (46.8%) haplotype, which is linked to the risk of scrapie development, suggested a genetic susceptibility to scrapie in RPL sheep. Although the frequency of ARR/ARR in RPL sheep was low, the highest frequency of the ARR/ARQ genotype could be helpful in increasing the number of individuals carrying the ARR/ARR genotype and reducing the risk of genetic defects within the population. <![CDATA[<b>Effects of Korean ginseng (<i>Panax ginseng</i> C.A. Meyer) root extract on egg production performance and egg quality of laying hens</b>]]> This study was conducted to determine the effect of Korean ginseng (Panax ginseng C.A. Meyer) root extract (PGRE) on egg production and egg quality characteristics of hens at the beginning of their laying period (20 weeks old). Four groups of commercial hens (Atak-S; Turkish native hybrid) were fed with diets containing 0 mg, 50 mg, 100 mg and 150 mg PGRE/kg. Experimental results indicated that dietary PGRE had no effect on feed intake, feed efficiency, egg mass (EM) or egg production parameters. Over 12 weeks, hen-day egg production (HDP) of the groups was 73.5%, 74.8%, 69.2% and 79.0%, respectively. The effect of different levels of PGRE on egg weight, shape index (SI), specific gravity, shell thickness, Haugh Unit (HU), yolk index (YI) and albumen index (AI) was not statistically significant during the entire experiment. Egg yolk colour was conspicuously lower in the 100 mg and 150 mg PGRE/kg groups than in the control. The L*, a* and b*, hue (H) and chroma (C*) values for eggshell colour were not significantly different among the groups, except for the colour difference (ΔΕ*, (L²+a²+b²)¹/2), where values in PGRE groups were higher than in the control group. The trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) and total phenolics concentration of PGRE were 598 ± 1.841 mmol trolox/kg, 15.45 ± 0.457 mmol TEAC/kg and 1.02 ± 0.03 g gallic acid equivalents (GAE)/kg, respectively. Serum glucose, cholesterol and triglyceride concentration were similar in the PGRE supplemented groups and the control. In conclusion, the dietary supplementation with PGRE did not affect the productivity performance traits and egg quality of hens at the beginning of the laying period. <![CDATA[<b>Growth responses, excreta quality, nutrient digestibility, bone development and meat yield traits of broiler chickens fed vegetable or animal protein diets</b>]]> This study was carried out to compare the performance of broilers fed diets containing only vegetable protein (VP) with birds that received an animal protein (AP) in their diets. Cobb 500 day-old male broiler chicks (n = 256) were randomly divided into four experimental groups. The two AP diets contained fish meal and soybean (SBF) and fish meal with canola (CMF); while the two VP diets contained predominantly soybean (SBM) or canola (CAN) meals. All diets were isoenergetic and isonitrogenous, and were pelleted, but amino acid levels were formulated on a total and not digestible basis. Feed intake up to 21 days was highest on the AP diets, and the lowest in the SBM treatment. Birds in the AP diet groups were significantly heavier at 21 days and 35 days than those on the VP diets. Up to 35 days, birds on AP diets had superior feed conversion ratio, while the CAN treatment was the poorest. Excreta moisture level was significantly higher in birds fed the VP diets than those on AP diets. Excreta pH and ammonia concentration were similar between treatments. Protein digestibility was higher in the AP than in the VP diets. Birds raised on VP diets had a significantly lower abdominal fat content than birds on the AP diets. Other meat characteristics measured in this experiment did not differ significantly. Bone development, in terms of breaking strength and latency-to-sit time, was significantly better on the AP diets than that of birds on the VP diets. The birds on the CMF diet had the longest tibia bone, while birds on SBM diet, the shortest. Total tibia ash content on the CMF diet was significantly increased, along with its iron and copper concentration, which were also significantly higher in birds on the same diet than the others. The responses of birds generally indicated that the AP diets were superior to the VP diets. <![CDATA[<b>Productive and reproductive performance of Dorper and its crossbreds under a Romanian semi-intensive management system</b>]]> The overall objectives of the research were to evaluate the effect of cross-breeding Dorper (DO) rams with Turcana (TA) ewes on growth and reproductive performances of F1 DOxTA and R1 DOx(DOxTA) crossbred lambs reared under a semi-intensive management system; to study the adaptability of the DO breed to Romanian farming conditions; and to evaluate the effects of melatonin implants outside the breeding season on reproductive performances in DO ewes. Animals were managed on cultivated pastures, with an average stocking rate of 12 head/ha. Additional 200 g concentrates/day were given for 90 days during the winter season and a three lambings per two years system was practised with the use melatonin implants for oestrous induction outside the natural breeding season. Dorper and F1 crossbreds were found to be highly precocious when put to the ram as ewe lambs, with an average fertility rate of 84.2% and 79.3%, respectively, compared with 19.3% in the TA controls (CG). The litter size in adult DO ewes was 136.6% versus 118.8% for the TA (CG). Dorper-sired progeny had significantly higher body weights of lambs at weaning (90 days) compared with TA purebreds (23.8 kg, 23.5 kg, 21.5 kg, 19.4 kg for DO, R1, F1 and TA, respectively). At the age of 8 months, all three DO genotypes were significantly heavier (46.1 kg, 40.7 kg and 43.5 kg for DO, F1 and R1, respectively) compared with the TA females, who reached 32.3 kg. Average daily gain from birth to 28 days of age was significantly higher in DO purebreds and F1 and R1 crossbreds compared with TA lambs (266.4 g, 253.8 g, 223.4 g and 157.3 g, respectively). Lamb survival rates until weaning were not affected by the genotype. When using melatonin implants in the DO ewes, the fertility rate increased to 88%, compared with a fertility of 41.6% in non-treated DO ewes. Out-of-season prolificacy was not affected by melatonin treatment, with litter size being 127% and 120% in treated and non-treated DO ewes, respectively. The DO breed performed well under Romanian semi-intensive management, and proved to be a highly adaptable breed to the new rearing conditions. <![CDATA[<b>Effective population size and inbreeding rate of indigenous Nguni cattle under <i>in situ</i> conservation in the low-input communal production system</b>]]> Nineteen rural Nguni cattle enterprises managed at communal and small-scale level were used in a study to determine population genetic parameters, level of Nguni genetic contribution, and risk status of community-based animal genetic resources. Chi-square tests were performed to ascertain the association between enterprise ownership and level of Nguni genetic contribution. Analysis of (co)variance was used to determine significant factors affecting breeding ratio, effective population size (Ne) and inbreeding rate per generation (∆F). About 75% of the animals in the pooled communities were pure Nguni, and the breed was classified as not at risk of extinction, while the individual enterprises were classified as being endangered-maintained without the exchange of germ plasm among them. There were no significant differences between communal enterprises (0.270 ± 0.0699) and small-scale (0.213 ± 0.0748) in the ratio of breeding males to breeding females. Pooled Ne was 348.14, whereas Ne was 19.5 ± 4.60 for communal enterprises and14.1 ± 5.03 for small-scale. It was concluded that enterprise ownership had no effect on small population genetic parameters in community-based in situ conservation programmes. It is recommended that policies be adopted to integrate enterprises, and increase herd sizes and Ne to preserve within-breed genetic diversity. <![CDATA[<b>Impact of Line 1 germplasm on South African Hereford cattle</b>]]> The goal of this research was to document the influence of Line 1 Hereford cattle, developed by the United States Department of Agriculture at its research facility in Miles City, Montana, on Hereford cattle in South Africa. Analytical approaches made use of both recorded pedigree and microsatellite marker information. Cattle with recorded performance data in South Africa were mated with Line 1 Hereford sires in silico and inbreeding coefficients were calculated for the resulting progeny. The relationship between South African and Line 1 Hereford cattle populations was estimated as twice the maximum inbreeding coefficient for the progeny of each South African animal. The calculated pedigree relationship of Hereford cattle registered in South Africa with Line 1 was 24%. Thirty-six South African Hereford cattle and a sample of 64 Line 1 animals were genotyped with 34 microsatellite markers. Based on a Bayesian model-based clustering method, the probability that the South African Hereford cattle were members of Line 1 was 0.38 ± 0.08. This research documents one aspect of the far reaching effects of the Line 1 Hereford population. <![CDATA[<b>Herbal extracts and organic acids as natural feed additives in pig diets</b>]]> This article summarizes experimental knowledge of the efficacy, modes of action and applications of herbal extracts and organic acids as feed additives for pigs. Herbal extracts comprise a wide variety of herbs, spices and, most importantly, essential oils. Organic acids, characterized as short-chain weak acids, are widely distributed in nature as normal constituents of herbal or animal tissues. Herbal extracts and organic acids can stimulate feed intake and the production of endogenous secretions and nutrient absorption, protect against the colonization of pathogenic microorganisms in the animal gut, reduce the fermentation process and production of toxic metabolites, and present a beneficial effect on the intestinal microbiota. Therefore, these compounds could replace antibiotics as growth promoters for pig production. However, a systematic approach to the efficacy and safety of herbal extracts and organic acids as feed additives for swine is still non-existent.