Sheep Breeds Research Articles

Investigation of Expression Levels of Transcription Factor Genes in Native Sheep Breeds of Türkiye

Investigation of Expression Levels of Transcription Factor Genes in Native Sheep Breeds of Türkiye

Are Eurasian badgers responsible for lamb predation? An investigation using farmer interviews, post‐mortem examination and molecular tools

Abstract This study investigates farmers' reports of lamb predation by badgers on Scottish sheep farms. Differentiating between predation and scavenging, and identifying the species responsible, is essential for livestock managers to effectively mitigate risk. Questionnaire‐style interviews established farmer perceptions of lamb predation by badgers and incidents of suspected predation were investigated on farms in 2022 and 2023 using post‐mortem examination and molecular tools. Farmers submitted 29 carcasses for post‐mortem. Of these, evidence of predation was present on 14 lambs (48%) and predation could not be ruled out for six further lambs (21%). No evidence of predation, but wounds consistent with scavenging after death, were present on nine lambs (31%). Nine (64%) of the 14 predated lambs also showed evidence of scavenging after death. Swabs were taken from 39 dead or injured lambs for potential predator/scavenger DNA recovery, and from 20 live control lambs. Badger DNA was obtained from the partial remains of two (5%) lambs. Badger DNA was not present on any of the carcasses submitted for post‐mortem or from any living, wounded lambs. Fox DNA was obtained from 34 (87%) dead or injured lambs, including all lambs that exhibited evidence consistent with predation at post‐mortem. Dog DNA was present on 12 (31%) lambs. While the results of this study cannot fully rule out the occurrence of lamb predation by badgers, no direct evidence was found to suggest that it does occur. The overall contribution of wildlife predation to lamb losses is considered to be low, but the results strongly suggest that foxes are likely to be responsible for lamb predation where it does occur. For livestock managers, a review of predator management strategies should be a key response to prevent future predation incidents. Practical implications. This study highlights the value of using post‐mortem examination and molecular evidence to accurately confirm predation events and to identify predator species, informing appropriate management interventions.

Regional Analysis of Sheep Business in Banjarnegara Regency

Banjarnegara Regency is home to the local Batur sheep, known for their significant body weight. The community has been raising Batur sheep for generations, aiming to develop them into a regional economic driver. This study aims to analyze potential areas for sheep livestock development in Banjarnegara Regency. The data used came from the farm statistics of the Directorate-General for Farm and Animal Health in 2021. The location quotient (LQ), localization index (LI), and specialization index (SI) method were used to perform regional analysis of sheep business. The results of the survey showed that the base area of sheep farming in Banjarnegara district is distributed in the districts of Karangkobar, Pejawaran, Batur, and Wanayasa. The localization and specialization index showed that sheep farming is spread evenly throughout the district of Banjaregara, not concentrated in a particular region.

Exploring the Economically Important Growth Traits and Environmental Influences on Akkaraman Lambs in Ankara

This study focused on the Akkaraman sheep breed, specifically examining the pre-weaning growth characteristics and Kleiber ratio, within the framework of Türkiye’s National Community-Based Small Ruminant Breeding Program. The research involved Akkaraman lambs born between 2017 and 2021 across 20 farms in the Ankara province. The dataset comprised 19,119 observations, covering key attributes such as birth weight, weaning weight, average daily weight gain, and the Kleiber ratio. Statistical analyses were conducted to identify outliers, assess normality, and develop linear models to explore the impact of environmental factors on the traits. Birth weight was significantly influenced by sex, birth type, birth season, birth year, and flock size. Weaning weight exhibited significant variations based on the same factors, emphasizing the importance of gender, birth type, birth season, birth year, and flock size. Average daily weight gain was notably affected by gender, birth type, birth season, birth year, flock size, and environmental factors, emphasizing their impact on growth. The Kleiber ratio demonstrated significant variations influenced by gender, birth type, birth season, birth year, and flock size. The results highlighted the intricate interplay between environmental factors and pre-weaning growth traits in the Akkaraman sheep breed. The study contributes valuable insights to enhance productivity and underscores the potential of the Akkaraman breed in Türkiye's overall agricultural development, considering its adaptability to arid climates and challenging pasture conditions

Meat of Sheep: Insights into Mutton Evaluation, Nutritive Value, Influential Factors, and Interventions

Meat from sheep offers an abundance of essential amino acids and trace elements essential for optimal human health and a delectable culinary delight. Because it has fewer calories and a lower cholesterol content than other meats, this succulent meat is not only delicious but also a nutritious choice. Globally, discriminating consumers have expressed profound appreciation for its irresistible flavor and nutritious composition. High-quality sheep breeds and lamb quality are in the spotlight as the market for sheep meat grows. Nevertheless, the demand for rapid growth and the use of antibiotics and other drugs have led to a shortage of high-quality mutton on the market. In the face of this emergency phenomenon, people add organic matter to the growth of mutton to improve the quality of mutton. This paper discusses the comprehensive evaluation methods of meat quality; summarizes the relationship between the nutritional components of meat and diet; discusses the genetic factors affecting meat quality attributes; feed nutrition, feeding methods, mutton storage methods, and related measures to improve the quality of mutton; and provides information on the current status of mutton and the challenges of ensuring high-quality meat supply in the future.

Polymorphism of the BMP15 and GDF9 genes in Romanov, Wrzosówka, and Podhale Zackel sheep in Poland

Various mutations in the BMP15 and GDF9 genes belonging to the transforming growth factor-β (TGF-β) superfamily have been shown to affect the prolificacy in sheep. Increasing the litter size is critical to the profitability of sheep production, but focusing on increasing the number of lambs born is only one of many factors that make sheep farming profitable. The study aimed to identify polymorphisms in BMP15 and GDF9 in Romanov, Wrzosówka, and Podhale Zackiel sheep breeds. The polymorphism of the coding parts of the BMP15 and GDF9 genes was determined based on DNA sequence analysis. Statistical analysis showed a significant relationship (p≤0.05) between the identified leucine deletion at the BMP15 locus (c.28_30delCTT) and increased fertility in heterozygous sheep. Statistically significant differences in the level of fertility were also identified between individuals with a mutation in the GDF9 gene - (c.978A> G, G6 - c.994G> A) and carriers of mutations in two BMP15 genes and GDF9 simultaneously.

Chromosome-level genome assembly of Guide Black-Fur sheep (Ovis aries)

Guide Black-Fur sheep (GD) is a breed of Tibetan sheep (Ovis aries) that lives in the Qinghai–Tibetan plateau region at an altitude of over 4,000 m. However, a lack of genomic information has made it difficult to understand the high-altitude adaptation of these sheep. We sequenced and assembled the GD reference genome using PacBio, Hi-C, and Illumina sequencing technologies. The final assembled genome size was 2.73 Gb, with a contig N50 of 20.30 Mb and a scaffold N50 of 107.63 Mb. The genome is predicted to contain 20,759 protein-coding genes, of which 98.42 have functional annotations. Repeat elements account for approximately 52.2% of the genomic landscape. The completeness of the GD genome assembly is highlighted by a BUSCO score of 93.1%. This high-quality genome assembly provides a critical resource for future molecular breeding and genetic improvement of Tibetan sheep.

Genomic Characterization of Local Croatian Sheep Breeds-Effective Population Size, Inbreeding & Signatures of Selection.

The Istrian (IS) and the Pag sheep (PS) are local Croatian breeds which provide significant income for the regional economy and have a cultural and traditional importance for the inhabitants. The aim of this study was to estimate some important population specific genetic parameters in IS (N = 1293) and PS (N = 2637) based on genome wide SNPs. Estimates of linkage disequilibrium effective population size (Ne) evidenced more genetic variability in PS (Ne = 838) compared to IS (Ne = 197), regardless of historical time (both recent and ancient genetic variability). The discrepancy in the recent genetic variability between these breeds was additionally confirmed by the estimates of genomic inbreeding (FROH), which was estimated to be notably higher in IS (FROH>2 = 0.062) than in PS (FROH>2 = 0.029). The average FROH2-4, FROH4-8, FROH8-16, and FROH>16 were 0.26, 1.65, 2.14, and 3.72 for IS and 0.22, 0.61, 0.75, and 1.58 for PS, thus evidencing a high contribution of recent inbreeding in the overall inbreeding. One ROH island with > 30% of SNP incidence in ROHs was detected in IS (OAR6; 34,253,440-38,238,124 bp) while there was no ROH islands detected in PS. Seven genes (CCSER1, HERC3, LCORL, NAP1L5, PKD2, PYURF, and SPP1) involved in growth, feed intake, milk production, immune responses, and resistance were associated with the found autozygosity. The results of this study represent the first comprehensive insight into genomic variability of these two Croatian local sheep breeds and will serve as a baseline for setting up the most promising strategy of genomic Optimum Contribution Selection.

A Sheep Identification Method Based on Three-Dimensional Sheep Face Reconstruction and Feature Point Matching.

As the sheep industry rapidly moves towards modernization, digitization, and intelligence, there is a need to build breeding farms integrated with big data. By collecting individual information on sheep, precision breeding can be conducted to improve breeding efficiency, reduce costs, and promote healthy breeding practices. In this context, the accurate identification of individual sheep is essential for establishing digitized sheep farms and precision animal husbandry. Currently, scholars utilize deep learning technology to construct recognition models, learning the biological features of sheep faces to achieve accurate identification. However, existing research methods are limited to pattern recognition at the image level, leading to a lack of diversity in recognition methods. Therefore, this study focuses on the small-tailed Han sheep and develops a sheep face recognition method based on three-dimensional reconstruction technology and feature point matching, aiming to enrich the theoretical research of sheep face recognition technology. The specific recognition approach is as follows: full-angle sheep face images of experimental sheep are collected, and corresponding three-dimensional sheep face models are generated using three-dimensional reconstruction technology, further obtaining three-dimensional sheep face images from three different perspectives. Additionally, this study developed a sheep face orientation recognition algorithm called the sheep face orientation recognition algorithm (SFORA). The SFORA incorporates the ECA mechanism to further enhance recognition performance. Ultimately, the SFORA has a model size of only 5.3 MB, with accuracy and F1 score reaching 99.6% and 99.5%, respectively. During the recognition task, the SFORA is first used for sheep face orientation recognition, followed by matching the recognition image with the corresponding three-dimensional sheep face image based on the established SuperGlue feature-matching algorithm, ultimately outputting the recognition result. Experimental results indicate that when the confidence threshold is set to 0.4, SuperGlue achieves the best matching performance, with matching accuracies for the front, left, and right faces reaching 96.0%, 94.2%, and 96.3%, respectively. This study enriches the theoretical research on sheep face recognition technology and provides technical support.

Circulation of small ruminant lentivirus in endangered goat and sheep breeds of Southern Italy

According to the Domestic Animal Diversity Information System (DAD-IS) of the FAO, Italy has one of the largest numbers of local small ruminant breeds among European countries. In Southern Italy, namely the Campania Region, Bagnolese and Laticauda sheep breeds and Cilentana goat breeds are considered endangered according to the DAD-IS. Conservation of endangered animal breeds is a goal of the European Union (EU). However, the role of infectious diseases as risk factors for endangered breeds has rarely been considered. Small ruminant lentiviruses (SRLV) infect sheep and goats, causing slow-progressive, persistent, and debilitating diseases that can lead to animal death and productivity loss. In this study, we investigated the presence of SRLV in Bagnolese, Laticauda, and Cilentana breeds using a commercial ELISA in parallel with an in-house ELISA. The results of the two tests were in good agreement (Cohen Kappa 0.84, 95 % CI = 0.76–0.93). Discrepancies between the two tests were resolved using western blotting. In total, 430 samples were tested (248 Bagnolese, 125 Laticauda, and 57 Cilentana). The apparent prevalence rates were 12.5 %, 6.4 %, and 1.7 % in Bagnolese, Laticauda, and Cilentana, respectively. In the molecular analysis of 11 proviral partial sequences, subtypes B2 and A24 were identified in two Bagnolese herds. Owing to the beneficial role of sheep and goat breeding in marginal areas, it is important to screen the entire population and implement control/eradication of SRLV infections in conjunction with each conservation program.

A meta-analysis approach for annotation and identification of lncRNAs controlling perirenal fat deposition in suckling lambs

Long non-coding RNAs (lncRNAs) are being studied in farm animals due to their association with traits of economic interest, such as fat deposition. Based on the analysis of perirenal fat transcriptomes, this research explored the relevance of these regulatory elements to fat deposition in suckling lambs. To that end, meta-analysis techniques have been implemented to efficiently characterize and detect differentially expressed transcripts from two different RNA-seq datasets, one including samples of two sheep breeds that differ in fat deposition features, Churra and Assaf (n = 14), and one generated from Assaf suckling lambs with different fat deposition levels (n = 8). The joint analysis of the 22 perirenal fat RNA-seq samples with the FEELnc software allowed the detection of 3953 novel lncRNAs. After the meta-analysis, 251 differentially expressed genes were identified, 21 of which were novel lncRNAs. Additionally, a co-expression analysis revealed that, in suckling lambs, lncRNAs may play a role in controlling angiogenesis and thermogenesis, processes highlighted in relation to high and low fat deposition levels, respectively. Overall, while providing information that could be applied for the improvement of suckling lamb carcass traits, this study offers insights into the biology of perirenal fat deposition regulation in mammals.

Growth performance of three Nigerian breeds of sheep fed different types of hay

Growth performance of three Nigerian breeds of sheep fed different types of hay

Socio-Economic Structure, Production Practices, Observations and Suggestions in Nomadic Sheep Production in Ordu province located in Black-Sea Region of Türkiye

Products obtained from farm animals meet the need for animal protein, which has an important place in human nutrition. In recent years, the demand for the products of small ruminants has been increasing. Products obtained from small ruminants are important in meeting the nutritional needs of the world population. Especially in light of the effect of global warming, small ruminants production has become even more important. Especially considering the production conditions of small ruminants, the nutritional needs of animals are met by grazing in the existing highlands. This study was conducted in Ordu province, located in the Black Sea Region of Türkiye. The Black Sea region, with its coasts and springs, is a region where breeders engage in nomadic animal husbandry. In the study, it was determined that 86.6% of the nomadic sheep breeders are producing Karayaka breed sheep while 13.4% are breeding Karayaka crossbreds. In the study, 47.9% of the breeders who participated in the survey live in the village and 45.1% live in the district. Percent 94.4 of the breeders were male and 5.6% were female. It was determined that 32.4% of the breeders were between the ages of 41-50 and 40.8% were primary school graduates. The rate of those who contribute to their livelihood through husbandry is 57.2%. The rate of those who want to continue small ruminant farming in the future is 82.9%. Additionally, it was determined that the majority of breeders attach importance to record keeping and animal health protection practices. In the enterprises where the study was conducted, difficulties were encountered in supplying feed and finding shepherds, and high feed prices and labor costs were stated as the most common problems. In nomadic sheep breeding, grazing and climate parameters in pastures and plateaus have a significant impact on the nutrition of the animals. Therefore, facilitating the transportation of sheep to pastures and plateaus and the sustainability of these areas will positively affect nomadic sheep breeding.

Challenges and Opportunities: Cattle / Sheep Farming Business in the City

This research investigates the challenges and opportunities associated with cattle and sheep farming businesses in urban environments, particularly emphasizing outstanding cattle farming enterprises in Depok. The study aims to provide an in-depth analysis of these businesses' strategies to address existing challenges and leverage potential opportunities. By exploring the innovative practices and adaptive measures employed by urban livestock farmers, this research seeks to uncover effective methods for breeders to navigate market dynamics, enhance operational efficiencies, and sustainably improve the productivity and quality of their livestock operations. Focusing on success stories from Depok, the study highlights how exemplary cattle farming businesses have thrived despite the constraints of an urban setting. It examines the role of technology, community engagement, and sustainable farming practices in driving their success. The findings offer valuable insights and recommendations for breeders, policymakers, and stakeholders on fostering a resilient and prosperous urban livestock farming sector. Ultimately, this research contributes to the broader discourse on urban agriculture, providing lessons on sustainable growth and productivity enhancement in urban livestock farming.

Base Characteristics, Preservation Methods, and Assessment of the Genetic Diversity of Autochthonous Breeds of Cattle, Sheep and Pigs in Serbia: A Review.

Preserving local autochthonous domestic animal populations and the products derived from them is a crucial aspect of managing human utilization of the biosphere. This management approach aims to ensure sustainable benefits for both present and future generations. The diversity of autochthonous domestic animal populations plays a vital role in the functionality and sustainability of the food production system. It encompasses both productive and non-productive aspects, contributing significantly to the overall health, nutrition, and food security of the landscape by providing a wide range of animal-derived food resources. Based on the data contained in the Draft Program of Rural Development, a significant presence of more than 44 autochthonous and local breeds of domestic animals has been noted in Serbia. In order to enable the sustainable preservation of local domestic animals, the competent Ministry of Agriculture of the Republic of Serbia has, through a number of projects, implemented models for the preservation of local breeds on farms (in situ), as well as provided technical assistance to small farms that keep animal collections. It also helps the local population to procure animals, conducts product quality research, and provides opportunities to integrate conservation programs through tourism. Given that molecular characterization is a key factor for the preservation of autochthonous breeds, in the Republic of Serbia, DNA markers are used for identification and to investigate the belonging to a specific breeds or strain. All the mentioned activities led to an immediate increase in the number of animals, which is especially true for the autochthonous breeds of cattle (Busha), sheep (Sjenicka, Svrljiska, and Vlach-vitohorn) and pigs (Mangalitsa, Moravka, and Resavka) that are discussed in this paper. In addition to the significant measures undertaken to preserve animal genetic resources (AnGR), it is necessary to continue to work primarily on ex situ conservation in order to prevent the loss of their gene pools. However, regardless of the evident effort that has been made to preserve autochthonous genetic resources in Serbia, we believe that there is still a lot of room for further improvement. This primarily refers to advanced technologies that have not been applied so far, mostly related to the identification of genomic regions associated with economic traits, resistance to diseases, and adaptability to emerging climate changes. In this way, the production capacity and functional characteristics of autochthonous species and breeds of domestic animals in Serbia will be improved.

Comparative study of the parasite load in two breeds of sheep in Mexico

Gastrointestinal parasites (GIP) produce great economic losses in livestock systems in Mexico, causing deficiencies in productive systems, mainly in food production; Gastrointestinal parasitosis constitutes a mechanism of loss, due to the high degrees of infestation experienced by these ruminants, which mainly causes anemia, liver and kidney damage, weight loss and large reproductive losses such as very prolonged postpartum anestrus. The prevalence of parasites in sheep is estimated between 63.4% to 90.2% prevalence, in a population of 8.9 million sheep in Mexico, distributed in different zoogeographic zones of the country. Based on the above, the objective of this study was to establish the foundations for the development of a breed or breeds of sheep resistant to gastrointestinal parasites (PGI). To achieve this objective, 183 sheep of the Criolla and Dorper breeds were randomly selected. These were under a grazing system and in addition, phenotypic characteristics were determined such as: body condition, FAMACHA, hematocrit (%). Fecal samples were taken from each animal and analyzed using sedimentation, flotation and direct coproparasitological tests, and the parasite load, eggs per gram of feces (HPG), was determined using the Mac Master chamber method (modified) by animal. To detect the damage caused by the different degrees of parasite infestation, tests were carried out on the metabolomics-metabolic profile of each animal depending on the type of parasite and total parasite load. The data obtained showed that the most prevalent GIP were: Strongyloides papillosus (38.15%), Trichostrongylus spp (32.91%), Haemonchus contortus (21.25%), Trichuris ovis (7.69), Oesophagostomun spp (2 .56%), Ascaris spp (1.56). and Fasciola hepatica (1.32%), this last parasite is not considered a gastrointestinal parasite, according to many authors, however, the laboratory does consider it. The values ​​of metabolites detected through the metabolic profile showed that the higher the parasite load-EGF, these metabolites fluctuated at low levels compared to clinically healthy animals (CHA) such as: glucose, PT, albumin, creatinine, while bilirubin tends to increase, the greater the parasite load-HPG, but this will also depend on the type of parasites that each animal presents; while the alkaline phosphatase enzyme tends to decrease when the EGF is higher. Hematocrit (%) values ​​decreased with respect to high parasite loads, mainly due to Haemochus contortus and Fasciola hepatica. In conclusion: GIP parasites play a significant role in the productive and reproductive development of these breeds of small ruminants, therefore, to produce sheep resistant to GIP it is necessary to detect which parasites are the most prevalent and which ones affect the metabolic activity of each animal or groups of sheep depending on their breed and diet, mainly, and that Creole sheep are more resistant to high GIP loads, they tend to lose weight, but not their reproductive capacity, finally their immune system has to control these loads of GPI, becoming animals with a high degree of resilience in relation to the Dorper breed.

Construction of a high-density genetic map and QTL localization of body weight and wool production related traits in Alpine Merino sheep based on WGR

BackgroundThe Alpine Merino is a new breed of fine-wool sheep adapted to the cold and arid climate of the plateau in the world. It has been popularized in Northwest China due to its superior adaptability as well as excellent production performance. Those traits related to body weight, wool yield, and wool fiber characteristics, which are economically essential traits in Alpine Merino sheep, are controlled by QTL (Quantitative Trait Loci). Therefore, the identification of QTL and genetic markers for these key economic traits is a critical step in establishing a MAS (Marker-Assisted Selection) breeding program.ResultsIn this study, we constructed the high-density genetic linkage map of Alpine Merino sheep by sequencing 110 F1 generation individuals using WGR (Whole Genome Resequencing) technology. 14,942 SNPs (Single Nucleotide Polymorphism) were identified and genotyped. The map spanned 2,697.86 cM, with an average genetic marker interval of 1.44 cM. A total of 1,871 high-quality SNP markers were distributed across 27 linkage groups, with an average of 69 markers per LG (Linkage Group). Among them, the smallest genetic distance is 19.62 cM for LG2, while the largest is 237.19 cM for LG19. The average genetic distance between markers in LGs ranged from 0.24 cM (LG2) to 3.57 cM (LG17). The marker density in the LGs ranged from LG14 (39 markers) to LG1 (150 markers).ConclusionsThe first genetic map of Alpine Merino sheep we constructed included 14,942 SNPs, while 46 QTLs associated with body weight, wool yield and wool fiber traits were identified, laying the foundation for genetic studies and molecular marker-assisted breeding. Notably, there were QTL intervals for overlapping traits on LG4 and LG8, providing potential opportunities for multi-trait co-breeding and further theoretical support for selection and breeding of ultra-fine and meaty Alpine Merino sheep.

The Relationship between Biofilm Phenotypes and Biofilm-Associated Genes in Food-Related Listeria monocytogenes Strains.

Listeria monocytogenes is an important pathogen responsible for listeriosis, a serious foodborne illness associated with high mortality rates. Therefore, L. monocytogenes is considered a challenge for the food industry due to the ability of some strains to persist in food-associated environments. Biofilm production is presumed to contribute to increased L. monocytogenes resistance and persistence. The aims of this study were to (1) assess the biofilm formation of L. monocytogenes isolates from a meat processing facility and sheep farm previously characterized and subjected to whole-genome sequencing and (2) perform a comparative genomic analysis to compare the biofilm formation and the presence of a known set of biofilm-associated genes and related resistance or persistence markers. Among the 37 L. monocytogenes isolates of 15 sequence types and four serogroups involved in this study, 14%, 62%, and 24% resulted in the formation of weak, moderate, and strong biofilm, respectively. Increased biofilm-forming ability was associated with the presence of the stress survival islet 1 (SSI-1), inlL, and the truncated inlA genes. Combining the phenotypic and genotypic data may contribute to understanding the relationships between biofilm-associated genes and L. monocytogenes biofilm-forming ability, enabling improvement in the control of this foodborne pathogen.

Profiling several key milk miRNAs and analysing their signalling pathways in dairy sheep breeds during peak and late lactation.

The comprehensive understanding of microRNAs (miRNAs) in sheep milk during various lactation periods and their impact on milk yield and composition remains limited. This study aimed to investigate the expression patterns of four highly expressed miRNAs in sheep milk and their association with milk composition and yield parameters during peak and late lactation stages. A total of 40 healthy 4-year-old Akkaraman (n = 20) and Awassi (n = 20) ewes registered with the Ministry of Agriculture and Forestry of the Republic of Türkiye were used in the present study. For miRNA isolation from milk, the Qiagen miRNeasy Serum/Plasma Advanced Kit was utilised following the manufacturer's instructions. The expression levels of miRNAs were assessed using Qiagen miRNA PCR Assays. The significant fold changes in the expression levels of oar-miR-30a-5p, oar-miR-148a and oar-miR-181a were observed between peak and late lactation periods in the Awassi sheep breed. Conversely, only oar-miR-30a-5p and oar-miR-148a exhibited statistically significant changes in the Akkaraman sheep breed during the same lactation periods. Furthermore, oar-miR-21-5p demonstrated a significant fold change exclusively in peak lactation compared to Akkaraman and Awassi ewes. The findings suggest that the expression of the analysed miRNAs is influenced by both the lactation stage and different sheep breeds. This study offers valuable insights into the relationship between key miRNA expressions in sheep milk and milk composition and yield parameters during peak and late lactation, contributing to the existing knowledge in this field.

Genomic structural variation contributes to evolved changes in gene expression in high-altitude Tibetan sheep

Tibetan sheep were introduced to the Qinghai Tibet plateau roughly 3,000 B.P., making this species a good model for investigating genetic mechanisms of high-altitude adaptation over a relatively short timescale. Here, we characterize genomic structural variants (SVs) that distinguish Tibetan sheep from closely related, low-altitude Hu sheep, and we examine associated changes in tissue-specific gene expression. We document differentiation between the two sheep breeds in frequencies of SVs associated with genes involved in cardiac function and circulation. In Tibetan sheep, we identified high-frequency SVs in a total of 462 genes, including EPAS1, PAPSS2, and PTPRD. Single-cell RNA-Seq data and luciferase reporter assays revealed that the SVs had cis-acting effects on the expression levels of these three genes in specific tissues and cell types. In Tibetan sheep, we identified a high-frequency chromosomal inversion that exhibited modified chromatin architectures relative to the noninverted allele that predominates in Hu sheep. The inversion harbors several genes with altered expression patterns related to heart protection, brown adipocyte proliferation, angiogenesis, and DNA repair. These findings indicate that SVs represent an important source of genetic variation in gene expression and may have contributed to high-altitude adaptation in Tibetan sheep.