Sheep Population Research Articles

Domestication and Genetic Diversity Analysis of Several Sheep Breeds in China

Sheep is the main livestock species in northern China. Under diverse climatic conditions, a gene pool of local sheep resources is now forming. There are many sheep breeds in northern China, including local breeds and hybrid breeds. However, little is known about the genetic background and genetic variation of local sheep populations in northern China. Therefore, our aims is to provide a characterization of the population structure and genetic relationship within sheep breeds in northern China, and to study its genetic relationship with other sheep breeds. We collected blood samples from 390 sheep for genetic diversity analysis using Reduced-Representation Genome Sequencing (RRGS). This study used bioinformatics methods to analyze linkage disequilibrium, population structure, evolutionary tree, selective sweep etc. The mixed model revealed in this study may be formed in the process of sheep breeding, partially overlapping with historical and archaeological findings. New information on the domestication and genetic variety of sheep is provided by this study, which will help sheep in the future be improved through genomics.

Expanding the application of haplotype-based genomic predictions to the wild: A case of antibody response against Teladorsagia circumcincta in Soay sheep

BackgroundGenomic prediction of breeding values (GP) has been adopted in evolutionary genomic studies to uncover microevolutionary processes of wild populations or improve captive breeding strategies. While recent evolutionary studies applied GP with individual single nucleotide polymorphism (SNP), haplotype-based GP could outperform individual SNP predictions through better capturing the linkage disequilibrium (LD) between the SNP and quantitative trait loci (QTL). This study aimed to evaluate the accuracy and bias of haplotype-based GP of immunoglobulin (Ig) A (IgA), IgE, and IgG against Teladorsagia circumcincta in lambs of an unmanaged sheep population (Soay breed) based on Genomic Best Linear Unbiased Prediction (GBLUP) and five Bayesian [BayesA, BayesB, BayesCπ, Bayesian Lasso (BayesL), and BayesR] methods.ResultsThe accuracy and bias of GPs using SNP, haplotypic pseudo-SNP from blocks with different LD thresholds (0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.00), or the combinations of pseudo-SNPs and non-LD clustered SNPs were obtained. Across methods and marker sets, higher ranges of genomic estimated breeding values (GEBV) accuracies were observed for IgA (0.20 to 0.49), followed by IgE (0.08 to 0.20) and IgG (0.05 to 0.14). Considering the methods evaluated, up to 8% gains in GP accuracy of IgG were achieved using pseudo-SNPs compared to SNPs. Up to 3% gain in GP accuracy for IgA was also obtained using the combinations of the pseudo-SNPs with non-clustered SNPs in comparison to fitting individual SNP. No improvement in GP accuracy of IgE was observed using haplotypic pseudo-SNPs or their combination with non-clustered SNPs compared to individual SNP. Bayesian methods outperformed GBLUP for all traits. Most scenarios yielded lower accuracies for all traits with an increased LD threshold. GP models using haplotypic pseudo-SNPs predicted less-biased GEBVs mainly for IgG. For this trait, lower bias was observed with higher LD thresholds, whereas no distinct trend was observed for other traits with changes in LD.ConclusionsHaplotype information improves GP performance of anti-helminthic antibody traits of IgA and IgG compared to fitting individual SNP. The observed gains in the predictive performances indicate that haplotype-based methods could benefit GP of some traits in wild animal populations.

Association of ovine follistatin gene polymorphisms with body measurements, fat-tail traits and morphometric of head in Iranian Mehraban sheep

The mature body size of sheep is a polygenic trait that is used as a main selection criterion for increasing meat production through genetic selection. The purpose of this study was to characterize polymorphisms of the follistatin gene (FST locus), which is known to regulate muscle hypertrophy by inhibiting both myostatin and activin. Using single-strand conformation polymorphism analysis (SSCP) and Sanger sequencing, we examined polymorphisms of the ovine FST gene (OAR_v.3.1; Chr 16, NC_019473.1) in Iranian Mehraban sheep (n = 100, seven-month-old male lambs) with records of body measurements, fat-tails, and head morphometry. Among the nine SSCP patterns A to I, we identified five single nucleotide polymorphisms (SNPs), including g.25632659 G>C, g.25632701 G>A, g.25633069 A>G, g.25633069 A>T, and g.25634085 G>C. The only amino acid-altering variant was g.25632659 G>C in exon 3 (p.216Thr > Ser). According to a subsequent statistical analysis, SSCP patterns A (g.25632659 G/C, g.25632701 G/G), B (g.25632659 C/C, g.25632701 G/A), C (g.25632659 C/C, g.25632701 A/A), D (homozygous reference; g.25633069 A/A), E (heterozygous; g.25633069 A/G) and F (homozygous variant; g.25633069 T/T) were significantly (P < 0.05) connected with body measurements. Furthermore, patterns A and B had significantly (P ≤ 0.05) longer forehead lengths than the lambs with the pattern C. Pattern I (homozygous variant; g.25634085 C/C) was significantly associated with an increased mouth width, and decreased eye length compared to patterns H (heterozygous; g.25634085 G/C) and G (homozygous reference; g.25634085 G/G). The findings of this study provide primary evidence of linking between the polymorphisms of the FST gene and body size in a small panel of Iranian Mehraban sheep population.

Implications of forage quality for population recovery of bighorn sheep following a pneumonia epizootic

AbstractAnimals are inherently tied to nutritional resources of the landscape. Added cost of coping with environmental stressors, like disease, can exacerbate nutritional limitations. Pneumonia, a respiratory disease caused primarily by bacterial pathogens, has caused massive declines in populations of bighorn sheep (Ovis canadensis) throughout western North America. Nevertheless, population dynamics following a pneumonia epizootic vary across populations, which has spawned the idea that ecological conditions may play a role in regulating populations after a die‐off. We used 2 bighorn sheep populations with contrasting dynamics to test the hypothesis that habitat quality on summer range affects population dynamics following a pneumonia epizootic. We sampled over 700 vegetation transects and quantified nutrient content of 2,093 forage samples of 127 genera on summer ranges to compare habitat quality (macro‐ and micronutrients in forage, biomass, plant cover, and species diversity) between the ranges. The population exhibiting growth, higher recruitment, and better nutritional condition had over double the herbaceous biomass in their core foraging areas in summer than the population exhibiting decline, lower recruitment, and poorer nutritional status. The population experiencing growth also had more macro‐ and micronutrients available on their summer range as a function of higher biomass along with higher species diversity. Although winter range often is considered the nutritional bottleneck for ungulates, we demonstrate that the conditions of summer range can have consequences for population dynamics. Habitat quality should be incorporated when considering management objectives and population recovery of large herbivores in the presence of disease; interactions between habitat quality and population dynamics still apply and likely are amplified with additional stressors like disease.

The complete mitogenome of blue sheep (Pseudois nayaur) from the Indian Himalayan Region and its comparative phylogenetic relationship with other related species

The ‘Bharal’ or ‘Himalayan Blue Sheep’ (Pseudois nayaur) is endemic to the Himalayan and Tibetan Regions. There are gaps in the available database for the blue sheep mitogenome sequencing from the Indian region. We sequenced and characterized the whole mitogenome of one blue sheep individual using the Illumina Nova-seq 6000 platform, which was 16,718 bp in length. It included 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and one non-coding control region (D loop). It was compared with other complete mitochondrial DNA sequences of blue sheep from the NCBI database. The whole mitogenome of blue sheep was found to be highly AT-biased (60%) and had a positive AT skew (0.121) and a negative GC skew (−0.341). In 13 PCGs of blue sheep, Leucine (15.58%) and tryptophan (2.72%) occurred most frequently. A typical secondary cloverleaf structure was observed for all tRNA genes except for tRNA-Ser, where a stable structure of dihydrouridine did not develop. The phylogenetic analysis showed Indian blue sheep population formed a separate clade with a genetic distance of 3.7 to 4.1% from the Chinese blue sheep population, suggesting it to be of a different lineage and genetically qualifies the status of distinct subspecies. The results of this study will help in further phylogenetic analysis of Indian blue sheep populations in the Western and Eastern Himalayan regions and in understanding lineage identification and evolution for further research.

Unraveling candidate genes related to heat tolerance and immune response traits in some native sheep using whole genome sequencing data

BackgroundIn the sheep breeding industry, heat stress caused by the general increase in global temperature has become a significant issue, having both direct and indirect effects on animal health and productivity. The identification of effective pathways for responding to heat stress and immune responses, as well as the discovery of related genes, can improve the production and sustainability of genetic diversity in this area. In this study, we used nucleotide diversity (θπ) and FST statistical measurements to analyze the genomic data of the native Iranian sheep in order to find potential genes related to heat adaptation and immune response. We also compared the whole genome sequencing data of 29 indigenous Iranian sheep (the Afshari, Ghezel, Makuei, Moghani, Shal, Zel, Karakul, Grey-Shiraz, Baluchi, and Kermani breeds) with a number of other sheep breeds from Asia (n = 28), Europe (n = 28), and Africa (n = 25) to evaluate the genetic structure of the Iranian sheep population. The resultsThe results from the sheep population genetic analysis showed a clear separation between different populations that corresponds well with their geographic origins. Iranian sheep were further divided into a southern and a northern group, which coincided with the most prominent climatic division in Iran. Our search to identify potential genomic regions under selection showed several candidate genes involved in (1) response to heat stress (SIK2, FER, ATP1A1, CDK5RAP3, and TLR4), (2) immune response in hot and dry environments (CD109, CR2, EOMES, and MARCHF1), (3) response to drought stress and adaptation to desert areas (ZFP1, PLCB1, and PDGFD), and also (4) response to heat stress by controlling digestive metabolism (HTR4, TRHDE, and ALDH1A3). ConclusionsThe findings of this study may aid in our understanding of the molecular processes by which tiny ruminants adapt to hot, dry environments. In addition to the results of earlier studies, our findings also revealed a number of novel candidate genes related to heat adaptation. These genes will be valuable for future studies to choose livestock breeds that live in desert regions.

Recovery and confirmation of Haemonchus contortus from abomasal contents of roe deer (Capreolus capreolus) in Eastern-Hungary (Biharugra): A diagnostic case study

Gastrointestinal parasites are ubiquitous. They occur both in wild and domesticated animals. Among such parasites of veterinary importance is the trichostrongyle worms, out of which the Haemonchus contortus species is regarded as the most pathogenic one in the small ruminant industry. The occurrence of this parasite in the sheep flock is now very well documented and an established fact in Europe, although the parasite was original of the warmer climatic region. Studies on the cross-transmission of H. contortus between the wild and domesticated animals are also on the rise although the question of the direction of transmission is still debated. This is an important area that needs to be addressed as it could potentially contribute indirectly to mitigating anthelmintic resistance. Hungary also has reported its share of the occurrence of the parasite, mainly in the sheep flock and a certain population of roe deer. The study presented here is the preliminary results of a diagnostic case study that confirms the presence of H. contortus in wild ruminant deer species that are close to the domesticated sheep population.

Genetic Diversity and Population Structure of Bulgarian Autochthonous Sheep Breeds Revealed by Microsatellite Analysis.

This study attempts to provide a deeper insight into the current genetic status of 12 Bulgarian autochthonous sheep breeds using microsatellite (SSR) markers. A total of 600 individuals from 50 flocks were analyzed using a panel of 13 SSR markers. In total, 228 alleles were found in the studied microsatellite loci. The mean number of alleles, the effective number of alleles, and the polymorphic information content (PIC) values per locus were 17.54, 5.250, and 0.799, respectively. The expected heterozygosity (He) for all breeds ranged from 0.70 to 0.82. The within-population heterozygote deficit (Fis) varied from -0.03 to 0.1, reflecting significant levels for 10 of the 12 breeds. The average genetic differentiation (Fst) was 0.046, revealing a low discrimination between the breeds. The genetic distance, principal coordinate analysis, and the structure analysis showed that two of the studied breeds-Local Stara Zagora/SZ/ and Local Karnobat/MK/-were the most distinct sheep populations. The Bayesian clustering approach suggested poor breed differentiation for the remaining 10 sheep breeds. The results suggest that proper management strategies and specific breeding policies need to be implemented in Bulgaria to avoid the intermixing of breeds and to reduce the erosion of breed purity observed in some breeds.

The Prevalence and Molecular Distinguishing of Brucella melitensis Rev1 Strain among Field Isolates the Brucella from Sheep and Goat Milk through PCR-RFLP Analysis of omp2 Gene Polymorphism

The present study was undertaken to characterize the prevalence and molecular distinguishing of Brucella melitensis field and vaccine Rev1 strains isolated from milk among the sheep and goat population. The study was carried out on flocks of sheep and goats suffering from Brucella infection outbreaks. A total of 171 milk samples were collected from different districts of the West Bank, part of Palestine, and isolated on Brucella agar. 86 cultures were confirmed by standard biochemical methods and screened for Brucella melitensis 16M of IS711 element by a conventional PCR technique. All these samples were also amplified for the omp2 gene to identify differences between field and Rev 1 strains in an infected flock. The results obtained from the PstI restriction enzyme pattern revealed that only 2 (4.5%) samples have specific polymorphism accomplished with the Brucella melitensis Rev1 strain. All other samples were restricted according to the Brucella melitensis 16M polymorphism pattern and originated from nonvaccinated flocks. Despite the adverse side effects of the Brucella melitensis vaccine, only a well-organized whole-flock vaccination and awareness campaign may inhibit the virulence of the field strain and, subsequently, reduce the prevalence of brucellosis infection among animals and humans in Palestine.

Phenotypic characterization of the Gamo highland sheep population in Gamo Zone, South Ethiopia

Phenotypic characterization of the Gamo highland sheep population in Gamo Zone, South Ethiopia

Cheese yield and nutrients recovery in the curd predicted by Fourier-transform spectra from individual sheep milk samples

The objectives of this study were to explore the use of Fourier-transform infrared (FTIR) spectroscopy on individual sheep milk samples for predicting cheese-making traits, and to test the effect of the farm variability on their prediction accuracy. For each of 121 ewes from 4 farms, a laboratory model cheese was produced, and 3 actual cheese yield traits (fresh cheese, cheese solids, and cheese water) and 4 milk nutrient recovery traits (fat, protein, total solids, and energy) in the curd were measured. Calibration equations were developed using a Bayesian approach with 2 different scenarios: (1) a random cross-validation (80% calibration; 20% validation set), and (2) a leave-one-out validation (3 farms used as calibration, and the remaining one as validation set) to assess the accuracy of prediction of samples from external farms, not included in calibration set. The best performance was obtained for predicting the yield and recovery of total solids, justifying for the practical application of the method at sheep population and dairy industry levels. Performances for the remaining traits were lower, but still useful for the monitoring of the milk processing in the case of fresh curd and recovery of energy. Insufficient accuracies were found for the recovery of protein and fat, highlighting the complex nature of the relationships among the milk nutrients and their recovery in the curd. The leave-one-out validation procedure, as expected, showed lower prediction accuracies, as a result of the characteristics of the farming systems, which were different between calibration and validation sets. In this regard, the inclusion of information related to the farm could help to improve the prediction accuracy of these traits. Overall, a large contribution to the prediction of the cheese-making traits came from the areas known as "water" and "fingerprint" regions. These findings suggest that, according to the traits studied, the inclusion of water regions for the development of the prediction equation models is fundamental to maintain a high prediction accuracy. However, further studies are necessary to better understand the role of specific absorbance peaks and their contribution to the prediction of cheese-making traits, to offer reliable tools applicable along the dairy ovine chain.

Single-nucleotide Polymorphism Scanning of Bone Morphogenetic Protein Receptor Gene and its Correlation with the Prolificacy of Plateau Tibetan Sheep

Background: It is not clear whether there are other motifs on the BMPIR gene in plateau-type Tibetan sheep and whether there is a strong association between the mutant locus and reproductive performance. Methods: Single-nucleotide polymorphisms (SNPs) of the BMPRIB gene in the Tibetan sheep populations from the Qinghai pastoral area in China were detected by Sanger sequencing and performed correlation analysis with litter size. Result: Four SNPs (g.597 G greater than A, g.746 A greater than G, g.864 C greater than T and g.1113 C greater than A) of BMPRIB gene were firstly screened in Tibetan sheep. In loci g.746, relevance analysis discovered that genotypes GG and AG had 0.70 (P less than 0.05) and 0.79 (P less than 0.05) litter sizes more than the genotype AA in Tibetan sheep, respectively. In loci g.597, Tibetan sheep with genotypes AA and GA had 0.21 (P less than 0.05) and 0.31 (P less than 0.05) litter sizes more than the genotype GG, respectively. The results showed that g.746 A greater than G and g. 597 G greater than A were regarded as assisted-markers in molecular. These findings provide ideas and insights into the reproductive performance of Tibetan sheep in China.

Genome-Wide Signal Selection Analysis Revealing Genes Potentially Related to Sheep-Milk-Production Traits.

Natural selection and domestication have shaped modern sheep populations into a vast range of phenotypically diverse breeds. Among these breeds, dairy sheep have a smaller population than meat sheep and wool sheep, and less research is performed on them, but the lactation mechanism in dairy sheep is critically important for improving animal-production methods. In this study, whole-genome sequences were generated from 10 sheep breeds, including 57 high-milk-yield sheep and 44 low-milk-yield sheep, to investigate the genetic signatures of milk production in dairy sheep, and 59,864,820 valid SNPs (Single Nucleotide Polymorphisms) were kept after quality control to perform population-genetic-structure analyses, gene-detection analyses, and gene-function-validation analyses. For the population-genetic-structure analyses, we carried out PCA (Principal Component Analysis), as well as neighbor-joining tree and structure analyses to classify different sheep populations. The sheep used in our study were well distributed in ten groups, with the high-milk-yield-group populations close to each other and the low-milk-yield-group populations showing similar classifications. To perform an exact signal-selection analysis, we used three different methods to find SNPs to perform gene-annotation analyses within the 995 common regions derived from the fixation index (FST), nucleotide diversity (Ɵπ), and heterozygosity rate (ZHp) results. In total, we found 553 genes that were located in these regions. These genes mainly participate in the protein-binding pathway and the nucleoplasm-interaction pathway, as revealed by the GO- and KEGG-function-enrichment analyses. After the gene selection and function analyses, we found that FCGR3A, CTSK, CTSS, ARNT, GHR, SLC29A4, ROR1, and TNRC18 were potentially related to sheep-milk-production traits. We chose the strongly selected genes, FCGR3A, CTSK, CTSS, and ARNT during the signal-selection analysis to perform a RT-qPCR (Reale time Quantitative Polymerase Chain Reaction) experiment to validate their expression-level relationship with milk production, and the results showed that FCGR3A has a significant negative relationship with sheep-milk production, while other three genes did not show any positive or negative relations. In this study, it was discovered and proven that the candidate gene FCGR3A potentially contributes to the milk production of dairy sheep and a basis was laid for the further study of the genetic mechanism underlying the strong milk-production traits of sheep.

Genetic rescue from protected areas is modulated by migration, hunting rate, and timing of harvest.

In terrestrial and marine ecosystems, migrants from protected areas may buffer the risk of harvest-induced evolutionary changes in exploited populations that face strong selective harvest pressures. Understanding the mechanisms favoring genetic rescue through migration could help ensure evolutionarily sustainable harvest outside protected areas and conserve genetic diversity inside those areas. We developed a stochastic individual-based metapopulation model to evaluate the potential for migration from protected areas to mitigate the evolutionary consequences of selective harvest. We parameterized the model with detailed data from individual monitoring of two populations of bighorn sheep subjected to trophy hunting. We tracked horn length through time in a large protected and a trophy-hunted populations connected through male breeding migrations. We quantified and compared declines in horn length and rescue potential under various combinations of migration rate, hunting rate in hunted areas and temporal overlap in timing of harvest and migrations, which affects the migrants' survival and chances to breed within exploited areas. Our simulations suggest that the effects of size-selective harvest on male horn length in hunted populations can be dampened or avoided if harvest pressure is low, migration rate is substantial, and migrants leaving protected areas have a low risk of being shot. Intense size-selective harvest impacts the phenotypic and genetic diversity in horn length, and population structure through changes in proportions of large-horned males, sex ratio and age structure. When hunting pressure is high and overlaps with male migrations, effects of selective removal also emerge in the protected population, so that instead of a genetic rescue of hunted populations, our model predicts undesirable effects inside protected areas. Our results stress the importance of a landscape approach to management, to promote genetic rescue from protected areas and limit ecological and evolutionary impacts of harvest on both harvested and protected populations.

Exploring the value of genomic predictions to simultaneously improve production potential and resilience of farmed animals.

Sustainable livestock production requires that animals have a high production potential but are also highly resilient to environmental challenges. The first step to simultaneously improve these traits through genetic selection is to accurately predict their genetic merit. In this paper, we used simulations of sheep populations to assess the effect of genomic data, different genetic evaluation models and phenotyping strategies on prediction accuracies and bias for production potential and resilience. In addition, we also assessed the effect of different selection strategies on the improvement of these traits. Results show that estimation of both traits greatly benefits from taking repeated measurements and from using genomic information. However, the prediction accuracy for production potential is compromised, and resilience estimates tends to be upwards biased, when families are clustered in groups even when genomic information is used. The prediction accuracy was also found to be lower for both traits, resilience and production potential, when the environment challenge levels are unknown. Nevertheless, we observe that genetic gain in both traits can be achieved even in the case of unknown environmental challenge, when families are distributed across a large range of environments. Simultaneous genetic improvement in both traits however greatly benefits from the use of genomic evaluation, reaction norm models and phenotyping in a wide range of environments. Using models without the reaction norm in scenarios where there is a trade-off between resilience and production potential, and phenotypes are collected from a narrow range of environments may result in a loss for one trait. The study demonstrates that genomic selection coupled with reaction-norm models offers great opportunities to simultaneously improve productivity and resilience of farmed animals even in the case of a trade-off.

Productive and reproductive performance of Dawuro highland sheep managed under community-based breeding program in Ethiopia.

The objective of this study was to evaluate growth and reproductive performance of highland Dawuro sheep population managed under a community-based breeding program in Ethiopia. Records used in the study were collected over 6 years (2017-2022). In the current study, 3554 records were considered. Studied traits were birth weight (BWT), 3-month weight (WWT), 6-month weight (SMWT), daily gain from birth to weaning (ADG0-3), daily gains from weaning to 6-month age(ADG3-6), litter size(LS), lambing interval (LI), and annual reproductive rates(ARR). The data were analyzed using general linear models of SAS software. The overall least squares mean (LSM± SE) for BWT, WWT, SMWT, ADG0-3, and ADG3-6 were 2.69±0.02; 14.6±0.49, 22.8±0.22 kg, 128.05±2.27 gram (g), and 71.5±0.23 gram respectively. Site difference exerted significantly on BWT, WWT, and SMWT. The result of WWT and SMWT results of Dawuro sheep were comparable with previously reported known Ethiopian sheep breeds. The overall least squares mean ± standard error of LS, LI and, ARR were 1.67±0.04 lambs, 239±31.91 days, and 2.19±0.06 lambs, respectively. WWT and SMWT traits showed good responses to selection. The general implication of the result to future improvement program was continue selection, strengthening the existing breeder cooperatives, integration of full animal health, feed packages, conservation of prolific flocks, improving the management of animals, expanding the current CBBP to adjacent potential kebele, create market linkage and scaling out the existing best practice to a new sites.

Genomic Diversity Analyses of Some Indigenous Montenegrin Sheep Populations

Montenegro has a great diversity of indigenous and locally developed sheep breeds, adapted to different regions and climates. However, the current trend of the steady decline in sheep populations means that some of them are threatened with extinction. The aim of this study was the investigation of the genetic diversity and population structure of five Montenegrin sheep populations, using the OvineSNP50K BeadChip. Data from the studied sheep were supplemented with publicly available genotypes of worldwide breeds to determine admixture contributions and genetic relationships. Higher genetic diversity and low inbreeding were observed in Pivska Pramenka and Sjenicka sheep, with Ho = 0.411, He = 0.423, and FROH&gt;2Mb = 0.056 and Ho = 0.421, He = 0.421, and FROH&gt;2Mb = 0.041, respectively. Zetska Zuja had much lower FIS (0.001) and high FROH inbreeding (0.090), indicating a small population size and genetic drift. An analysis of the genetic population structure showed that Montenegrin sheep populations are genetically distinct populations. This analysis revealed the presence of admixture in most sheep populations (high heterogeneity), while genetic purity was observed in Zetska Zuja. The obtained results will help in the conservation management of endangered Montenegrin sheep populations.

165 Randel Lecture: Androgen Excess Domestic Livestock Models—What can they Tell us About the Mechanisms Underlying Anovulation?

Abstract Ovulatory disorders are a major factor in female infertility. Our laboratory has identified several populations of cows and a population of sheep that have excess androgen (High A4) in dominant follicles and ovarian cortex cultures in the US and in the Middle East with increased steroidogenic enzyme production in somatic cells. Within our research herd, the High A4 females have irregular estrous cycles where behavioral estrus and ovulation are not coupled and are often anovulatory. Follicular waves of growth, during the estrous cycle, are disrupted in High A4 cows with development of persistent follicles, and an absence of normal follicular-wave estrogen patterns in blood plasma compared with Controls. Increased ovarian cortex fibrosis, oxidative stress markers and plasma pro- inflammatory lipids were present in High A4 cows indicating increased inflammation. High A4 granulosa cells have altered gene transcripts indicating cell cycle arrest and expression of genes enriched in other somatic cell types resulting in altered cell identity. Furthermore, High A4 ovarian cortex cultures secrete increased pro-inflammatory cytokines and have reduced follicle progression to later stages supporting follicular arrest. Treatment of High A4 ovarian cortex cultures with Vascular Endothelial Growth Factor 165 suppressed excess steroids, fibrosis, pro-inflammatory cytokines and relieved follicular arrest. Concentrations of Anti-Mullerian Hormone (AMH) were greater in High A4 vs Controls in both follicular fluid and ovarian cortex culture media supporting that AMH could be a factor contributing to follicular arrest. Many of the characteristics of High A4 cows and sheep identified are similar to polycystic ovary syndrome (PCOS) in women. Thus, High A4 cow and sheep are excellent models to unravel androgen excess molecular mechanisms involved in follicular arrest and female infertility contributing to anovulation.

Correlates of early reproduction and apparent fitness consequences in male Soay sheep.

Life history trade-offs are ubiquitous across species and place constraints on the timing of life history events, including the optimal age at first reproduction. However, studies on lifetime breeding success of male mammals are rare due to sex-biased dispersal and the requirement for genetic paternity inferences. We studied the correlates and apparent fitness consequences of early life reproduction among males in a free-living population of Soay sheep (Ovis aries) on St Kilda, Scotland. We investigated the factors associated with early breeding success and the apparent consequences of early success for survival and future reproduction. We used genetic paternity inferences, population data, and individual morphology measurements collected over 30 years. We found that individuals born in years with low-density population size had the highest early life breeding success and singletons were more likely to be successful than twins. Individuals that bred successfully at 7 months were more likely to survive their first winter. For individuals that survived their first winter, early breeding success was not associated with later breeding success. As individual heterogeneity affects breeding success, we believe that variation in individual quality masks the costs of early reproduction in this population. Our findings provide no evidence for selection for delayed age at reproduction in male Soay sheep.

Frequency and Characterisation of Anomalies and Fractures of the Caudal Spine in Sheep with Undocked Tails.

As tails are often docked within the first days of life, studies investigating tail malformations and injuries in sheep do not exist thus far. To address this gap in the literature, this research aimed to analyse the occurrence of vertebral anomalies and fractures in the tail within an undocked Merinoland sheep population. At 14 weeks of age, the caudal spines of 216 undocked Merinoland lambs was radiographically examined, and tail length and circumference were measured. Anomalies were documented and statistical correlation and model calculations were performed. The occurrence of block vertebrae was observed in 12.96% and wedged vertebrae in 8.33% of the sample. Of the animals, 59 (27.31%) exhibited at least one vertebral fracture, which were observed in the middle and caudal third of the tail. A significant correlation was found between the occurrence of fractures and tail length (r = 0.168) and number of vertebrae (r = 0.155). Conversely, the presence of block and wedged vertebrae was not significantly correlated with tail length, circumference, or number of vertebrae. Only the sex showed significant differences in the probability of axis deviation. These results emphasize the importance of breeding for short tails to avoid fractures.