Dorper Sheep Research Articles

Population structure and selective signature of Kirghiz sheep by Illumina Ovine SNP50 BeadChip.

By assessing the genetic diversity and associated selective traits of Kirghiz sheep (KIR), we aim to uncover the mechanisms that contribute to sheep's adaptability to the Pamir Plateau environment. This study utilized Illumina Ovine SNP50 BeadChip data from KIR residing in the Pamir Plateau, Qira Black sheep (QBS) inhabiting the Taklamakan Desert, and commonly introduced breeds including Dorper sheep (DOR), Suffolk sheep (SUF), and Hu sheep (HU). The data was analyzed using principal component analysis, phylogenetic analysis, population admixture analysis, kinship matrix analysis, linkage disequilibrium analysis, and selective signature analysis. We employed four methods for selective signature analysis: fixation index (Fst), cross-population extended homozygosity (XP-EHH), integrated haplotype score (iHS), and nucleotide diversity (Pi). These methods aim to uncover the genetic mechanisms underlying the germplasm resources of Kirghiz sheep, enhance their production traits, and explore their adaptation to challenging environmental conditions. The test results unveiled potential selective signals associated with adaptive traits and growth characteristics in sheep under harsh environmental conditions, and annotated the corresponding genes accordingly. These genes encompass various functionalities such as adaptations associated with plateau, cold, and arid environment (ETAA1, UBE3D, TLE4, NXPH1, MAT2B, PPARGC1A, VEGFA, TBX15 and PLXNA4), wool traits (LMO3, TRPS1, EPHA5), body size traits (PLXNA2, EFNA5), reproductive traits (PPP3CA, PDHA2, NTRK2), and immunity (GATA3). Our study identified candidate genes associated with the production traits and adaptation to the harsh environment of the Pamir Plateau in Kirghiz sheep. These findings provide valuable resources for local sheep breeding programs. The objective of this study is to offer valuable insights for the sustainable development of the Kirghiz sheep industry.

Integrating genome-wide association and transcriptome analysis to provide molecular insights into growth rates in sheep1

Investigating genetic markers and key genes associated with sheep growth rate using integrated multi-omics approaches could provide valuable insights for the sheep industry. Based on the average daily gain (ADG), fast-growing (Ncase=70) and slow-growing (Ncontrol=70) Hu sheep were selected for a genome-wide association study (GWAS). Ten Hu sheep (fast-growing, n = 5; slow-growing, n = 5) and ten Dorper sheep (fast-growing, n = 5; slow-growing, n=5) were selected for comparative transcriptome analysis. We identified hub genes and tissue-specific genes (TSGs) using weighted gene co-expression network analysis (WGCNA) and RNA sequencing (RNA-Seq) data from ten tissues, respectively. Ten genes were found within 50 kb distances of the significant single nucleotide polymorphisms (SNPs). Based on a comparative transcriptomic analysis, a total of 501 and 441 differentially expressed genes (DEGs) were identified in the HF vs. HS and DF vs. DS comparisons, respectively. We found some important signaling pathways closely associated with fat metabolism and energy metabolism, such as “regulation of lipolysis in adipocytes”, “Oxidative phosphorylation”, and “Thermogenesis”. Several DEGs play a crucial role in fat deposition (such as ADRB3, PDE3B, FABP4, SERPINE1, PLIN1, and FOXO6) and muscle development (MYL3). Using the WGCNA analysis, 15 genes were considered as hub genes associated with ADG. Integration of GWAS and RNA-Seq data indicates that BRINP3 and PENK may further influence the growth rate by regulating feeding behavior in sheep. Association analysis of 1,071 Hu sheep populations revealed that mutations in the BRINP3 (BRINP3 g.16903465 T>C) and PENK (PENK g.39289926 T>C) genes were significantly related to the growth traits (P < 0.05). Our research provides novel insights into understanding the molecular mechanisms underlying growth traits in sheep. BRINP3 and PENK genes may be potential key candidate genes related to sheep growth rate.

Genetic diversity of United States Rambouillet, Katahdin and Dorper sheep

BackgroundManaging genetic diversity is critically important for maintaining species fitness. Excessive homozygosity caused by the loss of genetic diversity can have detrimental effects on the reproduction and production performance of a breed. Analysis of genetic diversity can facilitate the identification of signatures of selection which may contribute to the specific characteristics regarding the health, production and physical appearance of a breed or population. In this study, breeds with well-characterized traits such as fine wool production (Rambouillet, N = 745), parasite resistance (Katahdin, N = 581) and environmental hardiness (Dorper, N = 265) were evaluated for inbreeding, effective population size (Ne), runs of homozygosity (ROH) and Wright’s fixation index (FST) outlier approach to identify differential signatures of selection at 36,113 autosomal single nucleotide polymorphisms (SNPs).ResultsKatahdin sheep had the largest current Ne at the most recent generation estimated with both the GONe and NeEstimator software. The most highly conserved ROH Island was identified in Rambouillet with a signature of selection on chromosome 6 containing 202 SNPs called in an ROH in 50 to 94% of the individuals. This region contained the DCAF16, LCORL and NCAPG genes that have been previously reported to be under selection and have biological roles related to milk production and growth traits. The outlier regions identified through the FST comparisons of Katahdin with Rambouillet and Dorper contained genes with known roles in milk production and mastitis resistance or susceptibility, and the FST comparisons of Rambouillet with Katahdin and Dorper identified genes related to wool growth, suggesting these traits have been under natural or artificial selection pressure in these populations. Genes involved in the cytokine-cytokine receptor interaction pathways were identified in all FST breed comparisons, which indicates the presence of allelic diversity between these breeds in genomic regions controlling cytokine signaling mechanisms.ConclusionsIn this paper, we describe signatures of selection within diverse and economically important U.S. sheep breeds. The genes contained within these signatures are proposed for further study to understand their relevance to biological traits and improve understanding of breed diversity.

Molecular signatures of Haemonchus contortus infection in sheep: A comparative serum proteomic study on susceptible and resistant sheep breeds

Due to the negative impact of Haemonchus contortus in the tropics and subtropics, the detection of serum protein profiles that occur in infected sheep is of high relevance for targeted selective treatment strategies (TST). Herein, we integrated proteomics with phenotypic traits to elucidate physiological mechanisms associated to H. contortus infection in susceptible (Dorper – D) and resistant (Santa Inês – S) sheep breeds. Naïve female lambs were infected with H. contortus third-stage larvae on day zero (D0), and samples were collected weekly, for 28 days. Feces were used for individual fecal egg counts (FEC) blood for packed cell volume (PCV) and serum for specific antibody quantification through ELISA. Sera was collected on D0 (-) and D21 (+), and analyzed using a LC-MS/MS based proteomics approach. FEC, PCV, and anti-H. contortus antibody levels confirmed the absence of infection on D0. On D28 there was a significant difference between the two breeds for logFEC means (D = 3774 and S = 3141, p=0.033) and PCV means (D = 16.3 % and S = 24.3 %, p=0.038). From a total of 754 proteins identified, 68 differentially abundant proteins (DAPs) were noted. Phosphopyruvate hydratase (ENO3) was a DAP in all comparisons, while S+ vs D+ and S- vs D- shared the highest number of DAPs (8). Each of the four experimental groups clustered separately in a principal component analysis (PCA) of protein profile. Among the DAPs, proteins associated with the innate and adaptive immune system were detected when comparing S- vs D- and S+ vs D+. In D-, some proteins were linked to stress response to handling, sampling and heat. Focusing on the consequences of infection in each breed, in the D+ vs D- comparison, upregulated proteins were associated with inflammation control and immune response, where downregulated proteins pointed to a negative impact of infection on tissue anabolism, compromising muscle growth and fat deposition. In the S+ vs S- comparison, upregulated proteins were related to immune response, while the downregulated proteins were possibly linked to muscular development and growth, impaired by infection. Collectively, it can be concluded that ENO3 regulation emerges as a potential factor underlying the differential immune response observed between Santa Inês and Dorper sheep infected with H. contortus. In turn, detected acute phase proteins (APPs) reinforce their relation with infection, inflammation and stress conditions, whereas THEMIS-like may contribute to the immune system in Dorper. GSDMD, Guanylate-binding protein and ACAN warrant further investigation as possible biomarkers for TST strategy development.

Ewe-lamb bond at birth and during lactation in an equatorial semi-arid environment is better in a native than in an introduced breed

Santa Ines and Dorper sheep are the most popular breeds in the Brazilian semi-arid region. The former is of local origin and less intensively selected for productivity, and the latter is an introduced exotic breed selected for meat production. Dorper lambs are heavier at birth than Santa Ines lambs, which might increase the need for birth assistance, negatively influencing the newborn and maternal behaviours. Dorper lambs grow faster, most likely influencing their behavioural strategies during lactation, depending less on their mother than Santa Ines lambs. The aim of this study was to compare the behaviours of Santa Ines and Dorper ewes and their lambs at birth and throughout lactation. A complementary aim was to determine if being single or twin lambs impact differently according to the breed. Twenty-five Santa Ines ewes and their 32 lambs (18 single and 14 twins) and 21 Dorper ewes and their 26 lambs (16 single and 10 twins) were used in the study. Mother-offspring behaviours were recorded from birth until 63 days after lambing. Dorper ewes had a greater incidence of dystocia (P = 0.02) and longer labour (P = 0.0001) than Santa Ines ewes. At birth, Santa Ines ewes displayed a greater frequency of low-pitched bleats (P = 0.0006) and tended to spend more time grooming their lambs than Dorper ewes (P = 0.07). Immediately after birth, Santa Ines lambs shook their head earlier than Dorper lambs (P = 0.003). The litter size effects were unrelated to the breed: ewes of single deliveries groomed their lambs earlier (P = 0.04), and those that delivered twins spent more time grooming the first lamb delivered (P = 0.01). Over the first two weeks after parturition, Santa Ines ewes displayed higher frequencies of head-up postures (P = 0.0001), high-pitched bleats (P = 0.02) and smelled their lambs more times (P = 0.0001) than Dorper ewes. Santa Ines lambs were closer to their mother when grazing (P = 0.0001), while Dorper lambs were closer to their mother when lying down (P = 0.049). In conclusion, Santa Ines sheep shows a stronger ewe-lamb bond than Dorper soon after parturition, and such differences persist at least until 9 weeks after lambing. The ewe-lamb bond was weaker in twin than single lambs, without differences in the degree of its strength between Santa Ines and Dorper sheep.

The impact of sheep grazing on shrub communities at the Afrikaner and Hereford grazing trials at Grootfontein in the Eastern Upper Karoo

In the Nama-Karoo, grazing by livestock is an important driver of Karoo shrub composition. Many different breeds of livestock are farmed in the Nama-Karoo, and the stocking rate varies greatly over the region. In this study we examine how grazing by dorper and merino sheep applied at three stocking rates affected two Karoo shrublands on a long-term grazing trial at Grootfontein in the eastern Karoo. The effects of grazing treatment on shrub communities at two sites of the Afrikaner-Hereford grazing trial differed greatly and were measurable after ten years of rest. At the sandier, grassier Afrikaner site, heavy grazing by dorper sheep had a significant effect on shrub composition, density and cover, whereas the effect of grazing treatment was less pronounced at the Hereford site. Lenient grazing by merino sheep resulted in a vastly different community compared to all other grazing treatments. Individual Karoo shrub species responded differently to grazing treatment. Overall shrub recruitment has faltered for all but three species, and populations were dominated by intermediate-sized and large individuals. Results indicate that grazing management, animal type and stocking rate are important determinants of Nama-Karoo rangeland composition and structure with evidence of a legacy effect longer than ten years.

Increasing GSH-Px Activity and Activating Wnt Pathway Promote Fine Wool Growth in FGF5-Edited Sheep.

Fibroblast growth factor 5 (FGF5) plays key roles in promoting the transition from the anagen to catagen during the hair follicle cycle. The sheep serves as an excellent model for studying hair growth and is frequently utilized in various research processes related to human skin diseases. We used the CRISPR/Cas9 system to generate four FGF5-edited Dorper sheep and only low levels of FGF5 were detected in the edited sheep. The density of fine wool in GE sheep was markedly increased, and the proportion of fine wool with a diameter of 14.4-20.0 μm was significantly higher. The proliferation signal in the skin of gene-edited (GE) sheep was stronger than in wild-type (WT) sheep. FGF5 editing decreased cortisol concentration in the skin, further activated the activity of antioxidant enzymes such as Glutathione peroxidase (GSH-Px), and regulated the expression of Wnt signaling pathways containing Wnt agonists (Rspondins, Rspos) and antagonists (Notum) in hair regeneration. We suggest that FGF5 not only mediates the activation of antioxidant pathways by cortisol, which constitutes a highly coordinated microenvironment in hair follicle cells, but also influences key signals of the Wnt pathway to regulate secondary hair follicle (SHF) development. Overall, our findings here demonstrate that FGF5 plays a significant role in regulating SHF growth in sheep and potentially serves as a molecular marker of fine wool growth in sheep breeding.

Use of data mining algorithms to predict body weight of Dorper sheep Breed in two selected villages of Lepelle-Nkumpi local municipality in Limpopo province, South Africa

Sheep farmers in village areas find it difficult to estimate body weight without the weighing tools. The best fitted model for estimation of sheep body weight is not conclusive. Classification and regression tree (CART), Chi-square automatic interaction detection (CHAID), Exhaustive chi-square automatic interaction detection (Ex-CHAID) and Multivariate adaptive regression spline (MARS) were used to predict body weight (BW) of 306 Dorper sheep (female = 244 and male = 62) aged 1 to 2 years from linear body measurement traits such as rump height (RH), rump length (RL), heart girth (HG), withers height (WH), and body length (BL). Goodness of fit criteria's such as Pearson's correlation coefficients (r), coefficient of determination (R2), Akaike's information criterion AIC and adjusted R2 (Adj.R2) were computed for data mining algorithms performance assessment. The results indicated that MARS was the best data mining algorithm with r of 0.979, R2 of 0.958, Adj.R2 of 0.957, RMSE of 2.503 and AIC of 422.25. The MARS model provided the most appropriate predictive capability in the prediction of body weight for Dorper sheep with HG, WH, RH, BL, and sex (male) as the important traits. As a result, MARS data mining algorithm might be used to identify factors that might be vital to improve body weight of Dorper sheep for breeding programs.

Effects of nonsynonymous single nucleotide polymorphisms of the KIAA1217, SNTA1 and LTBP1 genes on the growth traits of Ujumqin sheep.

Sheep body size can directly reflect the growth rates and fattening rates of sheep and is also an important index for measuring the growth performance of meat sheep. In this study, high-resolution resequencing data from four sheep breeds (Dorper sheep, Suffolk sheep, Ouessant sheep, and Shetland sheep) were analyzed. The nonsynonymous single nucleotide polymorphisms of three candidate genes (KIAA1217, SNTA1, and LTBP1) were also genotyped in 642 healthy Ujumqin sheep using MALDI-TOFMS and the genotyping results were associated with growth traits. The results showed that different genotypes of the KIAA1217 g.24429511T>C locus had significant effects on the chest circumferences of Ujumqin sheep. The SNTA1 g.62222626C>A locus had different effects on the chest depths, shoulder widths and rump widths of Ujumqin sheep. This study showed that these two sites can be used for marker-assisted selection, which will be beneficial for future precision molecular breeding.

Reducing fecal egg count through selective breeding alters dorper lamb response to Haemonchus contortus in an artificial challenge trial

Infection by gastrointestinal nematodes (GIN), particularly Haemonchus contortus, can be detrimental to sheep health and performance. Genetic susceptibility to GIN varies between breeds, with those lacking high levels of natural resistance often requiring frequent anthelmintic treatment when facing parasitic challenge. Genetic technology can serve as a tool to decrease GIN susceptibility via selection for sheep with reduced fecal egg count (FEC) estimated breeding values (EBVs). However, the physiological changes that result from implementation of this strategy are not well described. Additionally, there is a need for comparison of animals from recent selective breeding against breeds with inherent GIN resistance. In this study we administered a challenge of H. contortus to Dorper x White Dorper (DWD; n = 92) lambs that have been genetically selected for either low (DWD-) or high (DWD+) FEC EBVs and Barbados Blackbelly x Mouflon (BBM; n = 19) lambs from a genetically resistant breed backgrounds. Lamb FEC, packed-cell volume (PCV) and serum IgG were measured at intermittent levels over 5 weeks. At day 21 and day 35, the selectively bred DWD- had a lower mean FEC compared to DWD+, but were higher than BBM. Reductions in both PCV and serum IgG from initial day 0 levels were observed in DWD lambs, but not in BBM. Furthermore, from a subset of lambs (n = 24) harvested at day 21, DWD- only tended (p = 0.056) to have lower mean worm counts than DWD+, with BBM having the lowest mean worm count. Differentially expressed genes (DEGs) identified via RNA-sequencing of abomasal tissue at day 21 indicate a more pronounced Th2 immune response and more rapid worm expulsion occurred in iBBM than iDWD- and iDWD+ lambs. However, gene expression in DWD- suggests an association between reduced FEC EBV and gastric acid secretion and the ability to limit worm fecundity. Ultimately, selection of Dorper sheep for low FEC EBV can reduce susceptibility to GIN, but it will likely require multiple generations with this trait as a breeding priority before presenting a similar resistance level to Caribbean breeds.

Effects of Nano Selenium on Some Metabolic and Rumen Parameters in Dorper Sheep

The aim of the study was to investigate the effects of nano selenium (N-Se) supplementation on some metabolik parameters and rumen fermentation in sheep. In the study, twenty female Dorper sheep, average 60.1±0.44 kg of body weight were used and blood samples and rumen fluid were taken at the end of trial. The animals were randomly divided into two trial groups (n=10). The control animals received the basal ration without Se supplementation, containing a native Se content of 0.06 mg/kg DM. The other sheep were fed the same basal ration supplemented with 3 g/head/day N-Se. Trial were 66 days with 10 days of adaptation to feed and 56 days of feeding period. Serum total protein (p=0.514) and albumin (p=0.126) levels did not change by feeding N-Se. Serum T-cholesterol, triglycerides, AST (p=0.001) and ALT (p=0.030) levels were decreased in the N-Se-treated group when compared with the control. Supplementation of N-Se did not effect ruminal pH values (p=0.792), the molar concentration of acetic acid (p=0.133) and butyric acid (p=0.089), but the ammonia concentration (p=0.001) was decreased, and total VFA concentration (p=0.003) was increased. The ratio of acetate to propionate decreased due to the increasing of propionate concentration (p=0.034). The obtained results indicated that N-Se supplementation positively improved ruminal fermentation and metabolic status. It was concluded that N-Se can be used as an alternatively available selenium source in sheep.

Seroprevalence and risk factors of Toxoplasma gondii in sheep and goats of North West Province, South Africa

BackgroundThe protozoan parasite Toxoplasma gondii causes toxoplasmosis, one of the most prevalent parasitic zoonotic diseases with significant economic and public health implications worldwide. Infection with the parasite has a significant adverse effect on sheep and goat production and can frequently go undetected in the herd, resulting in abortions and weak or dead offspring. Although there are few studies on seroprevalence and risk factors associated with T. gondii infections in livestock in other provinces of South Africa, there is no data in the North West province. Therefore, a cross-sectional study was conducted to investigate the seroprevalence of T. gondii and risk factors associated with exposure in sheep and goats of the North West province of South Africa. Sera from 439 livestock (164 sheep and 285 goats) were collected and analysed for the presence of T. gondii IgG antibodies using indirect ELISA (Enzyme-linked immunosorbent assay). An assessment of potential risk factors in farms associated with seropositivity was also conducted using a structured questionnaire.ResultsOut of the 439 tested sheep and goats, 13.9% (61/439) were positive for IgG antibodies against T. gondii. Sheep and goats had seroprevalences of 19.5% (32/164) and 10.5% (29/275) respectively. In the multivariable logistic regression model, the risk of acquiring T. gondii was significantly higher in the mixed breed [Odds ratio (OR) = 71.07; 95% confidence interval (CI): 266.8-1893.1; p < 0.011)] animals than white dorper sheep and in farms that burn or bury aborted material (OR = 42.04; CI: 179.9-982.5; p = 0.020) compared to those that only burn aborted material. The risk was lower for the farms in Kagisano-Molopo (OR = 0.00; CI: 0.0-25.4; p = 0.015) and Mahikeng (OR = 0.00; CI: 0.0-4.9; p < 0.001) local municipalities than Greater Taung local municipality, and for the animals that drink water from dams (OR = 0.03; CI: 0.2–58.8; p = 0.021) than those that drink from boreholes.ConclusionThe seroprevalence and risk factors associated with transmission observed show that T. gondii infection is widespread in sheep and goats of the North West province.

Resistance of Gastrointestinal Nematodes to Anthelmintics in Sheep Production in Zimbabwe

Introduction: Sheep play a crucial role in enhancing the socio-economic welfare of individuals in numerous nations. Within sub-Saharan Africa, productivity levels are hindered by various factors, such as prevalent diseases, inadequate nutrition, climate variations, predators, severe weather, as well as infestations of both external and internal parasites. The purpose of the present study was to assess the extent of anthelmintic resistance (AR) observed on a sheep farm operating for commercial purposes in Zimbabwe. Materials and methods: Forty female weaner Dorper sheep, averaging 43 kg in body weight, were selected from Ballineety commercial sheep farm in Mashonaland Central, Zimbabwe. These sheep were then divided into four groups of ten each, receiving different treatments including ivermectin, albendazole, levamisole, and no treatment as a control. Each treatment was administered according to the manufacturer’s recommendations. Pre-treatment faecal samples (day zero) and post-treatment (day 14) were collected and subjected to the Faecal Egg Count Reduction Test (FECRT). Anthelminthic resistance was suggested (AR) by the presence of faecal eggs after treatment. Results: All the drugs indicated a decrease in egg counts by less than 90%. The effectiveness of ivermectin, albendazole, and levamisole was measured at 58.5%, 70.1%, and 85.8% respectively. These findings indicate that nematodes have developed resistance to all treatments. The larval cultures of the samples before and after treatment indicated a significant presence of Haemonchus spp. in the pooled samples. In contrast, the quantities of Trichostrongylus spp. and Oesophagostomum spp. were low but present in all treatments. Cooperia spp. was recovered in post-treatment larval cultures of groups that received anthelmintic. The present study reports lower-than-expected efficacy for ivermectin, albendazole, and levamisole based on the reduction of egg excreted post-treatment. Conclusion: A common worms population in sheep are AR in the current study area. Therefore, comprehensive nematode management programs along with complementary eradication strategies are essential for sustainable sheep production.

Combined transcriptome and metabolome analysis reveals breed-specific regulatory mechanisms in Dorper and Tan sheep

BackgroundDorper and Tan sheep are renowned for their rapid growth and exceptional meat quality, respectively. Previous research has provided evidence of the impact of gut microbiota on breed characteristics. The precise correlation between the gastrointestinal tract and peripheral organs in each breed is still unclear. Investigating the metabolic network of the intestinal organ has the potential to improve animal growth performance and enhance economic benefits through the regulation of intestinal metabolites.ResultsIn this study, we identified the growth advantage of Dorper sheep and the high fat content of Tan sheep. A transcriptome study of the brain, liver, skeletal muscle, and intestinal tissues of both breeds revealed 3,750 differentially expressed genes (DEGs). The genes PPARGC1A, LPL, and PHGDH were found to be highly expressed in Doper, resulting in the up-regulation of pathways related to lipid oxidation, glycerophospholipid metabolism, and amino acid anabolism. Tan sheep highly express the BSEP, LDLR, and ACHE genes, which up-regulate the pathways involved in bile transport and cholesterol homeostasis. Hindgut content analysis identified 200 differentially accumulated metabolites (DAMs). Purines, pyrimidines, bile acids, and fatty acid substances were more abundant in Dorper sheep. Based on combined gene and metabolite analyses, we have identified glycine, serine, and threonine metabolism, tryptophan metabolism, bile secretion, cholesterol metabolism, and neuroactive ligand-receptor interaction as key factors contributing to the differences among the breeds.ConclusionsThis study indicates that different breeds of sheep exhibit unique breed characteristics through various physiological regulatory methods. Dorper sheep upregulate metabolic signals related to glycine, serine, and threonine, resulting in an increase in purine and pyrimidine substances. This, in turn, promotes the synthesis of amino acids and facilitates body development, resulting in a faster rate of weight gain. Tan sheep accelerate bile transport, reduce bile accumulation in the intestine, and upregulate cholesterol homeostasis signals in skeletal muscles. This promotes the accumulation of peripheral and intramuscular fat, resulting in improved meat quality. This work adopts a joint analysis method of multi-tissue transcriptome and gut metabolome, providing a successful case for analyzing the mechanisms underlying the formation of various traits.

Genetic Polymorphism of Growth Hormone Gene in Dorper Sheep using PCR-RFLP

Background: The growth hormone gene has a significant impact on postnatal longitudinal growth and development as well as the metabolism of protein, carbohydrates, and fats moreover its effects indirectly relate to bone and skeletal development. The objective of the study was to identify a single nucleotide polymorphism of the growth hormone gene and its association with growth traits in Dorper sheep. Methods: Data were collected from 50 Dorper sheep of 1 to 2 years of age at the University of Limpopo Experimental farm. The objective of the study was achieved by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism and General Linear Model (GLM). Result: PCR-RFLP reports revealed different segment patterns resulting in two genotypes such as AA and AB genotypes. Marker-traits association analysis showed that no significant difference was observed between AA and AB genotypes regarding all the measured traits except with wither height and AA genotype was remarkably related to higher withers height than AB genotype. It can be concluded that GH1 could be used as a genetic marker for marker-assisted selection (MAS) during breeding for the improvement of withers height.

Performance of Dorper sheep fed on range grass and legume diets in a feedlot system in Taita Taveta and Makueni counties of Kenya

Performance of Dorper sheep fed on range grass and legume diets in a feedlot system in Taita Taveta and Makueni counties of Kenya

Estimation of genetic parameters for growth traits and kleiber ratio in dorper sheep breed

The study aimed to estimate genetic and phenotypic parameters for growth traits and Kleiber ratio in Dorper sheep breed. Data used in this study were collected over 12 years (2012–2023) at Debre Birhan Agricultural Research Center sheep research station in Ethiopia. Studied traits were body weights at birth (WT0), weaning (WT3), six month (WT6), and yearling (WT12) age; average daily gains from birth to weaning (ADG0-3), from weaning to six months (ADG3-6), from six months to yearling (ADG6-12); and Kleiber ratios from birth to weaning (KR1) and from weaning to six months (KR2). The (co)variance components were estimated with different animal models using Average Information Restricted Maximum Likelihood (AI-REML) procedure. The best-fitted model for each trait was determined using likelihood ratio tests. Phenotypic performance for WT3, WT6, WT12, ADG0-3 and ADG3-6 showed a decline trend at a rate of 0.216 kg, 0.794 kg, 0.671 kg, 2.601 g and 4.865 g over years respectively. However, WT3, WT6, WT12, ADG0-3 showed a positive genetic improvement trend at a rate of 0.029 kg, 0.043 kg, 0.049 kg and 0.257 g over years respectively. Year of birth had a significant effect (P < 0.001) on all studied traits. Model including direct genetic as well as permanent environmental effect (Model 2) was chosen as the most appropriate model for WT0. Model which included only direct genetic effect (Model 1) was the best-fit model for all other studied traits. Direct heritability estimates based on suitable models were 0.07 ± 0.06, 0.11 ± 0.06, 0.09 ± 0.07, 0.11 ± 0.09 0.11 ± 0.06, 0.00 ± 0.04, 0.15 ± 0.07 and 0.00 ± 0.04 for WT0, WT3, WT6, WT12, ADG0-3, ADG3-6, KR1 and KR2 respectively. The variance ratio for the permanent environmental effect was 0.13 ± 0.04 for WT0. Genetic correlations among the traits ranged from negative (−0.39) for WT0-KR1 to high (0.99) for WT3-ADG0-3 and phenotypic correlations ranged from negative (−0.31) for WT0-KR1 to high (0.98) for WT3-ADG0-3. The low direct heritability estimates for the studied traits indicated that genetic improvement by direct selection might be difficult. Further investigation for the unexpected declined trend of phenotypic performance over years need to be required.

Genetic variations of Toll-like receptor 4 gene in exon 2 of South African Dorper sheep.

The study was conducted to identify the sequence variation of Toll-like receptor 4 (TLR4) in exon 2 of South African Dorper sheep. Blood samples were collected from fifty (n = 50) South African Dorper sheep aged between 3 and 4 years. The Deoxyribonucleic acid (DNA) was extracted, amplified, and sequenced for the TLR4 gene. DNA sequencing was used to identify the sequence variations of the TLR4 gene in South African Dorper sheep. The results showed that one synonymous single nucleotide polymorphism (SNP) of the TLR4 gene in exon 2 position T2249C was identified. Two genotypes (TT and TC) were discovered from the identified SNP. The dominant genotype was TT (0.60) over TC (0.40), with the dominant allele T (0.80) over C (0.20). The results also indicated that the used population was in the Hady-Weinberg Equilibrium. Polymorphism genetic analysis findings suggest that the identified sequence variation of TLR4 in exon 2 of South African Dorper sheep was moderate polymorphism. TLR4 gene at exon 2 of South African Dorper sheep had the SNP (T>C) at position 2249 bp with two genotypes (TT and TC).

Dorper sheep in Africa: A review of their use and performance in different environments

Abstract The Dorper breed developed in South Africa is used either as a pure breed or crossbred with existing indigenous breeds by many countries across the African continent to improve sheep production. This article presents documented information on the adoption, use, and performance of Dorper sheep across the continent of Africa and opportunities for their more sustainable production under the changing climatic conditions in Africa. Apart from the well-documented information on the Dorper sheep in South Africa, published information on the performance of the sheep is mainly from Eastern Africa. Most countries initially retained purebred Dorpers in nationally owned institutions for multiplication and crossbreeding trials with different indigenous breeds prior to distributing the crossbreds to diverse livestock keepers. The offspring produced through crossbreeding programs with the Dorper have better growth rates than indigenous breeds in the different countries; however, the performance of Dorper sheep in South Africa has not been achieved in any of the other countries. Genomic studies including Dorper sheep have identified regions of interest for resistance to brucellosis and Mycoplasma ovipneumonia that imply adaptability to challenging environments within Dorper sheep. Unfortunately, limitations in systems for guided breeding and monitoring of sheep productivity in Africa have resulted in haphazard crossbreeding of the Dorper. Targeted efforts are required across the different countries to develop breeding programs for improving locally adapted Dorper sheep populations and their crosses with indigenous breeds. New science and technologies need to be innovatively packaged and used to identify and propagate more productive and resilient Dorper and Dorper-based breed-types for the increasingly challenging tropical African range environments.

Changes in the physiological, hematological and parasitological parameters of Dorper sheep in relation to residual feed intake and confinement environment

The selection of animals with greater feed efficiency has unknown parasitological and physiological parameters when confined in full sun or shade. Thus, we aimed to assess the effect of residual feed intake (RFI) and the confinement environment on the hematological, parasitological and physiological parameters in male Dorper sheep (n = 60; 30 with positive RFI and 30 with negative RFI) distributed in 2 confinement environments (full sun and shade), in a 2 × 2 factorial scheme, with 15 animals for treatment. Animals kept in the shade showed an increase (P < 0.05) of erythrocytes, hemoglobin and albumin. Animals kept in full sun showed higherOocysts gamma glutamyltransferase, direct bilirubin, transaminase aspartate and respiratory rate (P<0.05). There was a higher incidence of Eimeria spp oocysts in RFI negative animals (P<0.05). Positive RFI animals increased respiratory rate (P<0.05). The RFI did not influence the blood parameters of Dorper sheep, however, it had an effect on respiratory rate and presence of Eimeria spp. oocysts. Thermal environment promoted changes in blood parameters and the physiological parameters of Dorper sheep.