African Sheep Research Articles

Mitochondrial DNA variation of domestic sheep (Ovis aries) in Kenya

The history of domestic sheep (Ovis aries) in Africa remains largely unknown. After being first introduced from the Near East, sheep gradually spread through the African continent with pastoral societies. The eastern part of Africa was important either for the first diffusion of sheep southward or for putative secondary introductions from the Arabian Peninsula or southern Asia. We analysed mitochondrial DNA control region sequences of 91 domestic sheep from Kenya and found a high diversity of matrilines from the widespread haplogroup B, whereas only a single individual from haplogroup A was detected. Our phylogeography analyses of more than 500 available mitochondrial DNA sequences also identified ancestral haplotypes that were probably first introduced in Africa and are now widely distributed. Moreover, we found no evidence of an admixture between East and West African sheep. The presence of shared haplotypes in eastern and ancient southern African sheep suggests the possible southward movement of sheep along the eastern part of Africa. Finally, we found no evidence of an extensive introduction of sheep from southern Asia into Africa via the Indian Ocean trade. The overall findings on the phylogeography of East African domestic sheep set the grounds for understanding the origin and subsequent movements of sheep in Africa. The richness of maternal lineages in Kenyan breeds is of prime importance for future conservation and breeding programmes.

Contribution of microsatellites markers in the clarification of the origin, genetic risk factors, and implications for conservation of Tunisian native sheep breeds.

The genetic diversity and genetic relationship of the two main groups of African sheep, thin-tailed and fat-tailed sheep, represented by the indigenous Tunisian sheep breeds "Barbarine" (BAR, fat-tailed) and "Queue Fine de l'Ouest" (QFO, thin-tailed) were investigated. The genotypes of 110 animals belonging to these two breeds and their crossbreed (CRO) were assessed using 17 microsatellite markers. The results showed high levels of genetic diversity and a total of 256 alleles were identified in the whole population. The mean values of observed and expected heterozygosity were 0.719 and 0.789, respectively, and the mean allelic richness estimate was 10.89. The average FIS (0.112) and FIT (0.118) values over all loci indicated a notable level of inbreeding within the whole population. However, the FST value (0.007) showed a low level of genetic differentiation between these two native breeds. The high level of both gene flow and molecular coancestry coefficient detected between the two breeds and their CRO revealed an old miscegenation between the BAR and QFO breeds. The clustering analysis performed with the STRUCTURE software confirmed gene flow between these two breeds. Results arising from this study provide evidence regarding the genetic structure and variability of the two main local sheep breeds, and the implications of their actual management, which indicates the need for an urgent conservation strategy in order to prevent significant gene flow and preserve the remaining breed specificity for future generations.

Morphological characterisation of the coronary arteries in African sheep (Ovis orientalis). Differential analysis with those of humans and other animal species.

Despite the importance of the coronary system in the African sheep as a possible experimental model, there is little information about this particular vascular system. The objective of this investigation was to characterise morpho- logically the coronary arteries and their branches in African sheep. This descriptive cross-sectional study evaluated the coronary arteries and their branches of 62 hearts of short hair sheep. The right and left coronary ostia were perfused with a semi-synthetic resin (Palatal GP40L 85%; styrene 15%) dyed with mineral red. The morphological characteristics were evaluated using a digital calibrator and the biometrics of the coronary arteries and their branches were registered. The right coronary artery had a proximal calibre of 2.11 ± 0.46 mm. The subsinusal interventricular branch ended at the middle third of the homonym sulcus in 19 (30.6%) specimens. The left coronary artery had a diameter of 5.38 ± ± 1.59 mm and a length of 4.67 ± 3.32 mm. This artery bifurcated itself in the paraconal interventricular branch and the left circumflex branch in 57 (91.9%) hearts and trifurcated with an additional left diagonal branch in 5 (8.1%) spec- imens. Left coronary artery dominance was observed in 51 (82.3%) specimens, whereas in 11 (17.7%) cases the coronary circulation dominance was balanced. Due to the similitude in the features of the coronary arteries between African sheep and humans, this animal model can be proposed for procedural and haemodynamic activities.

Mitogenome revealed multiple postdomestication genetic mixtures of West African sheep.

Notable diversity observed within African ovine breeds makes them of great interests, but limited studies on genetic origins and domestications remain poorly understood. Here, we investigate the evolutionary status of West African native breeds, Djallonke and Sahelian sheep using mitogenome sequencing. Compared with other ovine mitogenome sequences, West African sheep were revealed a Eurasian origin, and the initially tamed sheep breeds in West Africa have been genetically mixed with each other and mixed with European breeds. Worldwide domestic sheep is deemed the Eurasian origin and migrated west to Europe and Africa and east to the Far East, in which dispersed and received selection for acclimation to autochthonic environment independently and ultimately evolved into different native breeds, respectively. Our results contribute to the comprehensive understanding of the domestic sheep origin and reveal multiple postdomestication genetic amelioration processes.

First molecular isolation of Mycoplasma ovis from small ruminants in North Africa.

Eperythrozoonosis is a small ruminant disease caused by the bacterium Mycoplasma ovis (formerly known as Eperythrozoon ovis). Whilst acute infection in sheep may result in an anaemia and ill thrift syndrome, most animals do not develop clinical signs. Molecular methods were used to compare and evaluate the prevalence of infection with M. ovis in sheep and goats in Tunisia. A total of 739 whole blood samples from 573 sheep and 166 goats were tested for the M. ovis 16S rRNA gene using PCR. The overall prevalence was 6.28% ± 0.019 (36/573). Only sheep were infected with M. ovis (p < 0.001), and the prevalence was significantly higher in central Tunisia (29.2%) compared with other regions (p < 0.05). The prevalence revealed significant differences according to breed and bioclimatic zones (p < 0.001). Furthermore, the prevalence in young sheep (35/330; 10.6%) was higher than in adults (1/243; 0.41%) (p < 0.001). Only sheep of the Barbarine breed were infected, with a prevalence of 11.8% (p < 0.001). This is the first molecular study and genetic characterisation of M. ovis in North African sheep breeds.

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

Traceability systems and origin based meat products in the South African sheep meat industry

ABSTRACTIn a consumer-driven world, consumers want to experience a connection between the product that they are consuming and the product's origin. To guarantee the validity of this connection and therefore the origin attribute of the product, traceability systems are required. The main purpose of this paper is to assess current traceability systems implemented in South African sheep abattoirs, thereby establishing their ability to guarantee the origin of a carcass. Research indicated that the South African sheep abattoirs have traceability systems in place and they can guarantee the origin of a meat product. The descriptive analysis and hypothesis tests identified the tipping factor for the implementation of a traceability system, as the requirement from retail markets to which these abattoirs deliver their product.

Direct greenhouse gas emissions of the South African small stock sectors

There are increasing concerns about the impact of agriculture and livestock production on the environment. As a result, it is important to have accurate estimations of greenhouse gas (GHG) emissions if reduction measures are to be established. In this study the direct GHG emissions from South African sheep and goats during 2010 were calculated. Calculations were done per province and in total. The Intergovernmental Panel on Climate Change (IPCC) methodology, adapted for tropical production systems, was used to calculate methane (CH4) and nitrous oxide (N2O) emissions on a Tier 2 level. Small stock is a key methane emission source in the South African livestock sector, and is responsible for an estimated 15.6% of the total livestock emissions. Small stock contributed an estimated 207.7 Giga gram (Gg) to the total livestock methane emissions in South Africa in 2010, with sheep producing 167 Gg and goats producing 40.7 Gg. Calculated enteric methane emission factors for both commercial and communal sheep of 8.5 kg/head/year and 6.1 kg/head/year, respectively, were higher than the IPCC default value of 5 kg CH4/head/year for developing countries. A similar tendency was found with goat emission factors. The highest sheep and goat methane emissions were reported for the Eastern Cape province, primarily because of animal numbers. Keywords : Greenhouse gas, methane, nitrous oxide, sheep, goats

The Origin of African Sheep: Archaeological and Genetic Perspectives

Indigenous African sheep genetic resources have been classified into two main groups, fat-tailed and thin-tailed sheep. The fat-tailed sheep are the most widely distributed, being found in a large part of North Africa (from Egypt to Algeria) and in Eastern and Southern Africa (from Eritrea to South Africa). The thin-tailed sheep are present mainly in Morocco, Sudan and in West Africa. African sheep were domesticated outside Africa. They share a common ancestry with European and Asian sheep. Archaeological information supports separate introductions and dispersion histories for the African thin-tailed and fat-tailed sheep. The first sheep entered Africa via the Isthmus of Suez and/or the southern Sinai Peninsula, between 7500 and 7000 BP. They were likely of the thin-tailed type. Fat-tailed sheep entered Africa through its northeastern part and the Horn of Africa. Mitochondrial DNA analysis supports a common maternal ancestral origin for all African sheep, while autosomal and Y chromosome DNA analysis indicates a distinct genetic history for African thin-tailed and sub-Saharan fat-tailed sheep. The main ancestral population of southern African fat-tailed sheep likely originated in East Africa. Further work is needed to assess the possible dispersion of sheep from western Africa to the southern African regions.

Allelic and genotypic frequencies of ASIP and MC1R genes in four West African sheep populations

In West Africa, consumers pay a major attention on the coat colour of the sheep due to religious and cultural reasons. White coated individuals reach selling prices up to three-fold higher than black coated sheep. The aim of this study was to ascertain the genotypic and allelic frequencies of MC1R and ASIP genes in order to assess possible implementation of breeding programmes focusing on the increase of the white coated sheep frequencies. A total of 113 individuals belonging to three Burkina Faso sheep breeds (Burkina-Sahel, Djallonke and Mossi) and one Niger sheep breed (Touareg) were genotyped for the MC1R and ASIP genes. The wild allele of the ASIP gene (Awt; 54.30%) was the most frequent in the four West African sheep, particularly in Burkina-Sahel (85%) and Touareg breeds (80%). The dominant black ED allele was not identified in Burkina-Sahel and Touareg. Most of the analysed individuals were homozygous for wild MC1R allele (E+/E+) with 100, 73.5, 59 and 100% frequency in Burkina-Sahel, Djallonke, Mossi and Touareg, respectively. The Awt/Awt was the most frequent genotype on the ASIP gene in the four West African breeds (80.53%). No individuals were homozygous for the deletion (allele Adel). Although, no routine methods for detection of the genetic basis of the recessive black coat colour patterns can be easily implemented, the current results suggest the feasibility of a selection programme aiming at decreasing the frequencies of the dominant black ED allele in Burkina Faso sheep breeds. Key words : Sheep, coat colour, MC1R gene, ASIP gene, Burkina Faso, Niger.

Prion protein gene polymorphism in four West African sheep populations

A total of 162 individuals, belonging to three Burkinabé and one Niger sheep populations, were analysed for prion protein (PrP) gene polymorphism at codons 136, 154 and 171. The ARQ allele was the most frequent in both the Burkinabé (86.7%) and the Niger (67.5%) sheep populations. The highly sensitive allele VRQ was not found in the sampled individuals. The highly resistant ARR allele was in very low frequency in the Burkina-Sahel (4.4%) and Mossi (3.2%) populations and was not present in the Djallonké and Touareg populations. Only 4 out of 15 possible PrP genotypes were identified in the sampled individuals. No favourable ARR/ARR genotypes were found in either of the breeds. Sequencing a subgroup of the samples allowed the identification of other five polymorphisms on the PrP gene sequence at codons 116, 138, 151, 237 and 240. The very low frequency of the ARR allele in the West African sheep should dissuade the implementation of a preventive selection programme aimed to increase resistance to scrapie, to avoid an extreme erosion of the genetic stock.

Nutrient content of uncooked and cooked meat from South African classes A2 lamb and C2 mutton

The study compared the nutrient content of selected joints of South African mutton (Class C2) (n = 18) and lamb (Class A2) (n = 18) carcasses of fat code 2 in both classes. South African sheep carcasses are classified according to age by dentition: Lamb carcasses of class A2 show the ruction of no incisors and mutton carcasses of class C2 of more than six incisors. Fatness is assessed by the thickness of subcutaneous fat. Chilled carcass sides were subdivided into the primal cuts. The cuts were dissected into meat (muscle, intermuscular and intramuscular fat), bone and subcutaneous fat (SCF). The soft tissue of the carcass was analysed for selected nutrients. It was found that South African lamb and mutton contain less fat than the nutrient values previously assumed as scientifically correct and presented in the National Food Composition Tables of the Medical Research Council (MRC), USDA. The results from this study emphasize the importance of country specific nutrient data on own food commodities.Keywords: Ovis aries, chemical composition, fat content, shoulder, loin, leg

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.

Comparison of four European endangered red sheep based on fleece characteristics

Patterns of wool variations found in modern sheep breeds may shed some light on the history of circum-Mediterranean migrations, which at present are still largely unknown. In this study, the characteristics of wool from five different local European breeds were investigated. Wool samples were taken from the following sheep breeds: Aranese, Roussillon Red, Castillonnais, Levant Red and Majorcan Red. Specimens were collected from 88 animals in different herds for each breed. The following sheep fleece characteristics were investigated: length of long-coarse, short-fine and kemp (medullated) fibres; their proportion within the staple; yield after scouring with isoalcohol; and fibre diameter. The amount of short-fine fibres was lower in the Levant Red and Majorcan Red breeds, with an inversely proportional amount of kemp fibres. Clean yield with isoalcohol was about 80 percent in all these breeds. Fleece characteristics offer a glimpse of possible morphologic relationships between the Levant Red and Majorcan Red that moreover exhibit a similarity in colour and a geographical proximity. Because very little is still known about the nature of the patterns of the fleece of Atlantic West and North African sheep, the importance of the African influence on existing European Mediterranean red sheep breeds remains to be clarified. A plausible hypothesis is that different influences would have left different traces, with a lesser impact on Pyrenean breeds.

Pregnancy and Outcome of Uterine Allotransplantation and Assisted Reproduction in Sheep

This pilot study was performed from March 2008 through February 2010 to demonstrate that pregnancy can be achieved in a uterine allograft in the sheep model with the guidance of assisted reproductive technology. Uterine allotransplantation was performed in 12 sexually mature African sheep (Sudanese and Ethiopian). All animals underwent uterine transplantation via a minilaparotomy incision using a Mobius retractor device. A control group of pregnant Romney Marsh sheep with nontransplanted uteri were used to compare fetal development, uterine and placental histologic findings, and blood samples of progeny of the uterine transplant recipient sheep. Fetal size was obtained from ultrasound measurements during the early (crown-rump length) and late (biparietal diameter and abdominal circumference) gestational periods. The primary end point variables included preoperative and postoperative management, embryo transfer protocol, intraoperative assessments, and physiologic cardiopulmonary changes in the lamb during the first 5 hours of life. Four months after the initial uterine transplantation, 5 of 12 uterine allografts were considered candidates for the embryo transfer procedure. Fresh and frozen blastocyst donors were transferred accordingly to the remaining 5 uterine allografts via a minilaparotomy incision. Three of these resulted in pregnancies. One was an ectopic gestation, 1 sheep carried the pregnancy to 105 days, and 1 delivered a fully developed lamb from the transplanted uterus that was delivered via cesarean section. Neonatal lamb blood gas values and chemistry, gross organ examination, and ventilation and respiratory compliance studies yielded results normal for gestational age. This first reported case demonstrates that pregnancy can be carried in an allotransplanted uterus, with the end result a successful delivery.

Rumen protozoa in South African sheep with a summary of the worldwide distribution of sheep protozoa

Protozoa species were identified in rumen contents of four domestic sheep (Ovis aries) from South Africa. All animals were fed a forage diet which consisted of 50% lucerne and 50% teff hay. Ten new host records were identified, bringing the total number of species and forms observed in sheep in South Africa to 30. The occurrence and geographic distribution of ciliate protozoa in both domestic and wild sheep from around the world are summarised. It was found that 15 genera and 131 species occur in domestic sheep globally.

A case study on cryopreservation of African sheep semen for the Red Maasai, Dorper breeds and their crosses

The objective of this study was to examine the effect of different concentrations of trehalose and raffinose in Tris-citric acid-glucose (TCG) egg yolk extender for the sperm freezability of Red Maasai sheep, another African breed- the Dorper and their crosses. The results showed that Red Maasai, Dorper and their crosses sperm could be cryopreserved by extending with 0.075 to 0.01 M trehalose or raffinose-TCG egg yolk extender. We conclude that the cryopreservation of currently under threat Red Maasai sheep due to uncontrolled exotic breeds sperm makes it possible to establish a gene bank for the storage of animal genetic resources for endangered species, under the management of the International Livestock Research Institute for future genetic options in an uncertain world. Key words: Red Maasai sheep sperm, freezability, raffinose, trehalose.

Genetic characterization of local Sudanese sheep breeds using DNA markers

Genetic diversity was investigated among 11 local Sudanese sheep populations. These populations were: Desert, with 6 sub-populations; Nilotics; Arid upland; West African; and Nilodesert, with 2 sub-populations. 15 microsatellites were used, a total number of 263 alleles being found, with expected heterozygosity ranging from 0.726 to 0.811. Principal component analysis revealed a distinct demarcation between the West African population and all other populations in Sudan and a moderate distance of Desert Dongla sheep from all other Desert populations. Structure modelling clustered West African, Arid upland and Nilotics populations in one group, and divided the Desert and Nilodesert populations into 2 mixed clusters with incomplete demarcation, reflecting cross breeding between these populations. Mitochondrial analysis indicated the dominance of the B haplotype in all populations, with about 10% of sheep carrying the A haplotype. The presence of the A and B haplotypes suggest that Sudan may be a contact zone between Asian and African sheep ancestors.

Prolificacy genotypes at BMPR 1B, BMP15 and GDF9 genes in North African sheep breeds

The aim of this research was to investigate the genetic structure at BMPR 1B, BMP15 and GDF9 prolificacy genes in five sheep breeds reared in Tunisia: Barbarine, Queue Fine de L’Ouest, Noire de Thibar, Sicilo-Sarde and D’man. Genomic DNA of 204 sheep was investigated for the FecB B (BMPR 1B), FecX R, FecX H, FecX I, FecX L, FecX G, FecX B (BMP15) and FecG H (GDF9) mutations. The sequence variability of the different DNA fragments utilised for genotyping was further investigated by Single Stranded Conformation Polymorphism (SSCP) and sequencing. All the above-mentioned mutations were absent in the five sheep breeds examined. SSCP analysis and sequencing allowed the detection of two nucleotide variations. A non-functional mutation (T/C transition at nt 747 of BMP15 cDNA known as B3) was found at the BMP15 gene, in the Noire de Thibar breed; this mutation was first detected in the Belclare sheep. A new nucleotide change G/A at nt 1159 of BMP15 cDNA, causing the amino acid change A119T in the mature peptide, was detected in the Barbarine breed for the first time. The highly prolific D’man ewes were monomorphic for the absence of all the known prolificacy alleles.

Validation of the FAMACHA © eye colour chart using sensitivity/specificity analysis on two South African sheep farms

A validation study of the FAMACHA © system for clinical evaluation of anaemia due to Haemonchus contortus was conducted on two commercial sheep farms in the summer rainfall region of South Africa. In this region, the Haemonchus season lasts from October to April. On Farm 1 the system was tested over a period of five successive years in consecutive sets of young stud Merino replacement rams and ewes examined at intervals of 3–5 weeks over each Haemonchus season, under routine farming conditions. When FAMACHA © scores of 3, 4, and 5 and haematocrit values of ≤22%, ≤19%, and ≤15% were separately considered to be anaemic, sensitivity on Farm 1 ranged from a maximum of 83% for a haematocrit cut-off of ≤15%, to 40% for a haematocrit cut-off of ≤22%. Sensitivity increased to 93% when FAMACHA © scores of 2, 3, 4, and 5 were considered anaemic at a cut-off value of ≤19%, but the positive predictive value decreased to 0.43, indicating that many non-anaemic animals would be treated. The analysis indicated a high level of classification bias on Farm 1, with the animals consistently being classified one FAMACHA © category lower (i.e. less anaemic) than reality. On Farm 2 the test was conducted over two successive years in yearling rams evaluated at weekly to fortnightly intervals during each worm season. Every ram judged to be in FAMACHA © category 4 or 5 was bled for haematocrit determination, and it was only dewormed with effective anthelmintics if the haematocrit was 15% or lower. When FAMACHA © scores of 3, 4, and 5 and haematocrit values of ≤22% and ≤19% were separately considered to be anaemic on Farm 2, sensitivity ranged from 64% for a haematocrit cut-off of ≤22%, to 80% for a cut-off of ≤19%. For identical haematocrit cut-off values and proportions of the sampled flock considered to be diseased as for Farm 1, sensitivity was always higher for Farm 2. On the other hand, further analysis of the data indicated that the magnitude of the error on Farm 1 was very consistent on average over the entire trial period. The results of this study indicate that (i) persons introduced to the system should not only be trained, but also be evaluated for accuracy of application; (ii) the sensitivity of the FAMACHA © diagnostic system should ideally be evaluated at shorter intervals to avoid production losses due to failure to detect anaemic animals which may be at risk of death; (iii) that calibration of the FAMACHA © scoring is essential per individual evaluator, and (iv) that animals should be examined at weekly intervals during periods of the highest worm challenge.