South African Sheep Breeds Research Articles

Physicochemical, volatile compounds, oxidative and sensory profiles of the Longissimus muscle of six South African sheep breeds

Context The scarcity of water and feed for sheep is a characteristic feature in the dryland areas of South Africa, and adversely affects meat production and quality. To address this challenge, breeds with high water, feed and production efficiencies must be used to produce meat of desirable quality. Aim The study aimed to compare physicochemical, volatile compounds, oxidative and sensory profiles of the Longissimus muscle from selected South African sheep breeds raised under intensive feeding conditions. Methods Physicochemical, oxidative, volatile compounds and sensory profiles of the Longissimus muscle from lambs of indigenous (Damara, n = 10; Pedi, n = 8), indigenous composite (Dorper, n = 10; Meatmaster, n = 9) and exotic composite (Dohne Merino, n = 10; South African Merino, n = 10) breeds that were penned individually and fed a lamb-finishing diet ad libitum over a 42-day test period were evaluated. Results Dohne Merino had the highest intramuscular fat content, whereas Damara and Pedi had the lowest (P ≤ 0.05). Meat lightness increased over time, with Pedi having the highest values on Day 7 of retail display at 4°C, followed by the Merinos (P ≤ 0.05). On Day 7, meat from the Merinos had the highest lipid oxidation values, whereas Damara and Pedi had the lowest (P ≤ 0.05). The lowest meat protein oxidation values on Day 7 were recorded for the Meatmaster, followed by Dohne Merino (P ≤ 0.05). Relative to the other breeds, Dohne Merino had the greatest concentrations of alcohols, aldehydes and acidic volatile compounds, and the lowest concentrations of esters (P ≤ 0.05). In addition, the Merinos had meat that was slightly more tender and juicy (P ≤ 0.05) than that of Damara and Dorper. Conclusions Even though indigenous breeds produced meat with comparable oxidative shelf-life and sensory quality attributes to composite breeds under intensive feeding conditions, they had leaner meat than the later breeds. Implications The observed variations in meat physicochemical and oxidative shelf-life parameters allow producers to select breeds that are best suited to their production systems, resources and market requirements.

Meat production, feed and water efficiencies of selected South African sheep breeds

The study compared water intake, balance and efficiency, nutrient intake, digestibility and utilisation, growth performance, carcass attributes and income over feed costs for six South African sheep breeds; Pedi, Damara, Meatmaster, Dorper, Dohne Merino and Merino. Wether lambs (4–5 mo) were adapted to a pelleted total mixed diet containing 143.5 g crude protein/ kg DM and 10.29 MJ/ kg DM metabolisable energy for 21 d followed by 7 d and 42 d of digestibility and performance data collection, respectively. Water and nutrient intakes were lowest in Pedi and highest in Meatmaster (P ≤ 0.05). Compared to other breeds, Damara and Meatmaster had higher (P ≤ 0.05) DM digestibility, nitrogen balance and average daily gain, while Dorper and Damara had higher (P ≤ 0.05) neutral detergent fibre and ether extract digestibility, respectively. Pedi had lower (P ≤ 0.05) water balance than the rest of the breeds. Water and feed conversion ratios were lowest for the Pedi and Damara and highest for Dohne Merino (P ≤ 0.05). Damara and Pedi had lower (P ≤ 0.05) dressing percentages, hot and cold carcass weights than the other breeds. The lowest and highest income over feed costs were reported for Pedi and Dohne Merino, respectively. It was concluded that although Damara and Pedi had the most inferior meat production attributes, they were the most feed and water efficient breeds.

Effects of direct-fed lactic acid bacteria on weight gain and ruminal ph of two South African sheep breeds

A ruminant’s digestion depends on microbial degradation of feed rather than endogenous enzyme degradation as in most monogastric animals. The study was conducted to assess the effects of Lactic Acid Bacteria (LAB) strains administered as direct-fed microbials on weight gain and ruminal pH of Damara and Meatmaster sheep breeds. Sixty-four Damara and Meatmaster sheep breeds [Damara males (36.6 ± 8.3 kg); Damara females (28.9 ± 6.9 kg); Meatmaster males (24.6 ± 3.4 kg); Meat master females (21.5 ± 3.1 kg)] were subjected to a 30-day trial and divided into five treatment groups as follows: pellets with no antibiotic and no probiotics administered (T1); pellets with no antibiotics, only Lactobacillus rhamnosus SCH administered (T2); pellets with no antibiotics, only Lactobacillus rhamnosus AF3G administered (T3); pellets with no antibiotics, with the combination of Lactobacillus rhamnosus SCH and Lactobacillus rhamnosus AF3G, administered (T4); pellets fortified with antibiotic and no probiotic administered (T5). The animals were fed on commercial pellets fortified with or without antibiotics. Animals were each weighed, and rumen fluids were collected using a stomach tube, and pH was read immediately, before and at the end of the trials. Data obtained were subjected to analysis of variance using SPSS version 4.0. The results showed that the effect of treatment, sex and some of their interactive effects were significant (p <0.001) on the body weight of sheep irrespective of breed. The effect of treatments revealed that the animals in the combination of probiotics gained more weight than those in other groups. Damara breed had a heavier body weight than Meatmaster while males were 6 kg heavier relative to females (p <0.001). Only breed was significant (p <0.05) on weight gained. Treatment (p <0.05), breed (p <0.001) and their interactive effect (p <0.05) were significant on ruminal pH. The highest pH value was 7.27 for the T5 group and 7.37 for the Damara breed. Results suggest that LAB may have beneficial effects on the growth performances of sheep and therefore may be suitable as future growth promoters in sheep production, as they don't have any harmful residues compared to antibiotics.

Runs of homozygosity analysis of South African sheep breeds from various production systems investigated using OvineSNP50k data

BackgroundPopulation history, production system and within-breed selection pressure impacts the genome architecture resulting in reduced genetic diversity and increased frequency of runs of homozygosity islands. This study tested the hypothesis that production systems geared towards specific traits of importance or natural or artificial selection pressures influenced the occurrence and distribution of runs of homozygosity (ROH) in the South African sheep population. The Illumina OvineSNP50 BeadChip was used to genotype 400 sheep belonging to 13 breeds from South Africa representing mutton, pelt and mutton and wool dual-purpose breeds, including indigenous non-descript breeds that are reared by smallholder farmers. To get more insight into the autozygosity and distribution of ROH islands of South African breeds relative to global populations, 623 genotypes of sheep from worldwide populations were included in the analysis. Runs of homozygosity were computed at cut-offs of 1–6 Mb, 6–12 Mb, 12–24 Mb, 24–48 Mb and > 48 Mb, using the R package detectRUNS. The Golden Helix SVS program was used to investigate the ROH islands.ResultsA total of 121,399 ROH with mean number of ROH per animal per breed ranging from 800 (African White Dorper) to 15,097 (Australian Poll Dorset) were obtained. Analysis of the distribution of ROH according to their size showed that, for all breeds, the majority of the detected ROH were in the short (1–6 Mb) category (88.2%). Most animals had no ROH > 48 Mb. Of the South African breeds, the Nguni and the Blackhead Persian displayed high ROH based inbreeding (FROH) of 0.31 ± 0.05 and 0.31 ± 0.04, respectively. Highest incidence of common runs per SNP across breeds was observed on chromosome 10 with over 250 incidences of common ROHs. Mean proportion of SNPs per breed per ROH island ranged from 0.02 ± 0.15 (island ROH224 on chromosome 23) to 0.13 ± 0.29 (island ROH175 on chromosome 15). Seventeen (17) of the islands had SNPs observed in single populations (unique ROH islands). The MacArthur Merino (MCM) population had five unique ROH islands followed by Blackhead Persian and Nguni with three each whilst the South African Mutton Merino, SA Merino, White Vital Swakara, Karakul, Dorset Horn and Chinese Merino each had one unique ROH island. Genes within ROH islands were associated with predominantly metabolic and immune response traits and predomestic selection for traits such as presence or absence of horns.ConclusionsOverall, the frequency and patterns of distribution of ROH observed in this study corresponds to the breed history and implied selection pressures exposed to the sheep populations under study.

The genomic architecture of South African mutton, pelt, dual-purpose and nondescript sheep breeds relative to global sheep populations.

South Africa has a diverse array of phenotypically distinct and locally adapted sheep breeds that have been developed for different production systems ranging from mutton to wool and pelt, and some dual-purpose and nondescript breeds kept by smallholder farmers. This study investigated genetic diversity, population genetic structure and divergence between South African sheep breeds in order to gain an insight into breed history and genomic architecture aligned to breeding goals and production systems. The Illumina OvineSNP50 BeadChip was used to genotype 400 sheep belonging to 14 breeds representing mutton, pelt and mutton and wool dual-purpose breeds. Nguni sheep were included as a representative of indigenous nondescript breeds that are reared by smallholder farmers. Seeking a clearer understanding of the genetic diversity of South African breeds relative to global populations, 623 genotypes of sheep from worldwide populations were included in the analysis. These sheep breeds included six African, two Asian and eight European breeds. Across breeds, genetic diversity ranged from observed heterozygosity (H0 )=0.26±0.02 in Namaqua Afrikaner to H0 =0.38±0.01 in Dohne Merino. The overall mean H0 was 0.35±0.04. The African and Asian populations were the most inbred populations with FIS ranging from 0.17±0.05 in Grey Swakara and Ronderib Afrikaner sheep to 0.34±0.07 in the Namaqua Afrikaner. The South African Dohne Merino (FIS =0.03±0.01), SA Merino (FIS =0.05±0.04) and Afrino (FIS =0.09±0.02) and other global Merino-derived breeds were the least inbred. The first principal component explained 27.7% of the variation and separated the fat- and rump-tailed sheep (i.e. Swakara, Nguni, Blackhead Persian, Ethiopian Menzi, Meatmaster) from the Merino and Merino-derived breeds and the Dorset Horn. The second principal component separated the Merino and Merino-derived breeds from the English breed of Dorset Horn. Overall, South African indigenous breeds clustered together with indigenous breeds from other African and Asian countries. The optimal admixture cluster (K=20) revealed various sources of within- and amongst-breed genomic variation associated with production purpose, adaptation and history of the breeds. The Blackhead Persian, Nguni and Namaqua Afrikaner breeds differed significantly from other breeds, particularly with the South African Mutton Merino and Dorset Horn. Breed-differentiating SNPs were observed within genomic regions associated with growth, adaptation and reproduction. Genes such as RAB44, associated with growth and meat/carcass traits, differentiated the Blackhead Persian from the Dorset Horn and South African Mutton Merino. The MAP2 and HRAS genes, which are associated with immune traits involving Toll-like receptors and Chemokine signalling pathways, differentiated the Nguni from the Dorset Horn. The current results give insight into the current status of the sheep genetic resources of South Africa relative to the global sheep population, highlighting both genetic similarities as well as divergence associated with production systems, geographical distribution and local adaptation.

Analysis of carcass characteristics and fat deposition of Merino, South African Mutton Merino and Dorper lambs housed in a feedlot

The objective of this study was to determine the effect of time spent in a feedlot on the size of the various fat depots and the distribution of the main tissues (muscle, bone, and fat) of three common South African sheep breeds. Lambs were supplied with a balanced diet (16% protein, 10 MJ ME/kg feed) ad libitum and had free access to water. Lambs from each breed were divided into six groups, which were slaughtered at 21-day intervals until a production period of 105 days had been reached. During carcass dressing, visceral and renal fat was removed and expressed as a percentage of carcass weight. The subcutaneous fat (SCF) depth was measured on the longissimus lumborum at the 13th rib position using an electronic calliper. The proportion of muscle, bone and fat was determined by dissecting a three-rib cut made on the prime rib between the 9th and 11th ribs. The percentage of visceral and renal fat increased throughout the production period for all breeds. The percentage of renal fat was up to 2.9% higher than the percentage visceral fat in both SAMM production groups. Dorper lambs tended to have high SCF levels (5.6 mm fat after 42 days) due to the early maturing nature of the breed. They reached a maximum fat depth of 20.4 mm fat after 105 days. The SAMM lambs tended to deposit SCF at a slower rate and the late maturing Merino breed was found to be much leaner, and did not reach the high fat levels of the SAMM or Dorper lambs. The percentage of muscle and bone in all carcasses decreased with an increase in the number of days in the feedlot, while the percentage of carcass fat increased during this period. The increase in late maturing adipose tissue in all breeds as they become older is amplified by the restricted movement in the feedlot and high energy diet that the lambs receive.

Evaluation of the OvineSNP50 chip for use in four South African sheep breeds

Relatively rapid and cost-effective genotyping using the OvineSNP50 chip holds great promise for the South African sheep industry and research partners. However, SNP ascertainment bias may influence inferences from the genotyping results of South African sheep breeds. Therefore, samples from Dorper, Namaqua Afrikaner (NA), South African Merino (SA Merino) and South African Mutton Merino (SAMM) were genotyped to determine the utility of the OvineSNP50 chip for these important South African sheep breeds. After quality control measures had been implemented, 85 SA Merino, 20 Dorper, 20 NA and 19 SAMM samples remained, with an average call rate of 99.72%. A total of 49 517 (91.30%) SNPs on the chip met quality control measures and were included in downstream analyses. The NA had the fewest polymorphic loci, 69.20%, while the SAMM, Dorper and SA Merino had between 81.16% and 86.85% polymorphic loci. Most loci of the SA Merino, Dorper and SAMM had a MAF greater than or equal to 0.3. In contrast, the NA exhibited a large number of rare alleles (MAF < 0.1) and a uniform distribution of other loci across the MAF range (0.1 < MAF ≤ 0.5). The NA exhibited the least genetic diversity and had the greatest inbreeding coefficient among the four breeds. The results of the Dorper, SA Merino, and SAMM compare favourably with those of international breeds and thus demonstrate the utility of the OvineSNP50 chip for these breeds. Effects of SNP ascertainment bias, however, could be seen in the number of non-polymorphic loci and MAF distribution of the three commercial breeds in comparison with those of the NA. The implementation of methods to reduce the effect of SNP ascertainment bias and to ensure unbiased interpretation of genotype results should therefore be considered for future studies using OvineSNP50 chip genotype results. Keywords: Dorper, genome-wide, Merino, Namaqua Afrikaner, OvineSNP50, SA Mutton Merino, SNP

The adaption of the South Africa sheep industry to new trends in animal breeding and genetics: A review

The history of sheep breeding research in South Africa can be divided roughly into four eras, namely the research and development phase, the commencement of recording and evaluation, the expansion of recording schemes, and, most recently, the adaptation of schemes to international benchmarks. The most recent era has presented scientists with the greatest challenges, namely the inclusion of genomic breeding values in routine sheep recording and of disease-resistance traits during routine evaluation. The establishment of reference populations for the major South African sheep breeds to estimate genomic breeding values is an immediate challenge. This process may be facilitated by a number of genetic resource flocks that are phenotyped for traits that are not routinely recorded in the national evaluation. A limited number of these animals are also genotyped. There is strong evidence that resistance of sheep to external and internal parasites is heritable, and may be improved by purposeful selection. Efforts should be concentrated on the inclusion of disease resistance traits in national analyses where appropriate. However, seen against the background that South African investment in research is appreciably less than in developed countries, lack of funding and high-capacity manpower may impede rapid progress. There thus seem to be many challenges for future generations of sheep breeding scientists. Keywords : Capacity, disease resistance, genomic selection

South African sheep breeds: Population genetic structure and conservation implications

This paper details the population genetic structure of South African indigenous, locally developed and introduced breeds using microsatellite markers, and the conservation implications of these results. Blood samples from 622 sheep, comprising 20 breeds, were collected from different regions in South Africa. All animals were genotyped at 12 microsatellite loci. Average unbiased heterozygosity (Hz) was lowest in the fat-rumped breeds (0.466); compared to higher average Hz values of 0.555 and 0.598 in the composite and indigenous fat-tailed breeds; and still higher values of 0.659 and 0.662 in Karakul and the wool breeds respectively. Analysis of patterns of differentiation showed that the average Fst value between fat-rumped and the fat-tailed indigenous breeds was 0.180, with an average Fst=0.184 between indigenous fat-tailed and wool types, and a higher average Fst value of 0.260 between fat-rumped and wool type breeds. Fst values within breeds were generally lower. Results from both Bayesian analysis (STRUCTURE) and a neighbor-joining tree based on standard genetic distance confirmed the known patterns of relationships among these groups and (in some instances) breeds. The results of this study also suggest that the indigenous breeds studied have some uniqueness, which may well translate to local adaptation over time. These results thus provide additional support for programs aimed at the conservation of indigenous and locally developed breeds, in line with international programs that emphasize the conservation of indigenous animal genetic resources.

Production of five Merino type lines in a terminal crossbreeding system with Dormer or Suffolk sires

This study details the production performance of ewes and lambs that originated from a terminal crossbreeding experiment that involved five Merino type dam lines and two terminal crossbreeding sire lines from 1999 to 2002. Ewe lines were SA Mutton Merino (SAMM), SAMM rams crossed to Merino ewes (SAMM cross), Dohne Merino, as well as specialist Merino lines selected for clean fleece weight (FW+) and for an increased reproduction rate (Rep+). Dormer and Suffolk rams were used as sire breeds on these ewes. Data include 777 birth and 605 weaning records of lambs and 562 production year records of ewes. At birth the progeny of SAMM ewes were heavier than those of the other ewe lines, while FW+ ewes produced smaller lambs at birth than SAMM cross and Rep+ ewes. Lamb survival was not significantly affected by ewe line or sire breed. The progeny of the dual-purpose ewe lines (SAMM, SAMM cross and Dohne Merino) were heavier than those of Merino ewes (FW+ and Rep+) at weaning. No sire breed difference was found for birth or weaning weight. The joining weights of dual-purpose ewe lines were higher than those of Merinos. Although considerable variation was found between ewe lines in terms of lamb output (number or weight of lamb weaned per ewe joined), the only significant difference was for weight of lamb weaned between SAMM cross and FW+ Merino ewes. Means for weight of lamb weaned per joining (in kg) were 37.3 for SAMM ewes, 39.6 for SAMM cross ewes, 35.5 for Dohne Merino ewes, 28.9 for FW+ ewes and 34.6 for Rep+ ewes. No differences in ewe reproduction were found between ewes joined to Dormer or Suffolk rams. The clean wool production of SAMM ewes amounted to 46% of that recorded in FW+ ewes. Corresponding percentages were 68% for SAMM cross ewes, 74% for Dohne Merino ewes and 90% for Rep+ ewes. The wool of SAMM ewes was slightly coarser in diameter than those of SAMM cross and FW+ ewes, which in turn was coarser than those of Rep+ and Dohne Merino ewes. The economic viability of crossbreeding programs involving the respective ewe lines would depend on the ratio between the prices of wool and lamb. No conclusive advantage could be demonstrated in favour of any of the sire breeds. Keywords: Fibre diameter, Lamb growth, Lamb output, Reproduction, South African sheep breeds, Wool yield South African Journal of Animal Science Vol.33(4) 2003: 223-232

A comparison of leather properties of skins from ten different South African sheep breeds

Extracted from text ... A comparison of leather properties of skins from ten different South African sheepbreedsM.A. Snyman 1 and C.A. Jackson-Moss 21 Grootfontein ADI, P/Bag X529, Middelburg, (EC), 59002 International School of Tanning Technology, P.O. Box 2085, Grahamstown, 6140e-mail:Dier6@karoo1.agric.zaIntroductionSkins contribute significantly to the value of slaughter animals. It is therefore essential that the true valueof the skins of different breeds is known to ensure that producers receive the optimum remuneration for theirproduct. A project in which the tanning properties of skins of ten different South African woolled, mutton and dualpurpose sheep breeds were evaluated, was done by Grootfontein Agricultural Development Institute, in co-operationwith ..