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The current study attempts to investigate the differences in gene expression in longissimus thoracis muscles between sheep breeds acclimated to diverse environments. Changthangi sheep inhabits the cold arid plateau of Ladakh, at an altitude above 3000 m with prevalence of rarefied atmosphere. Muzzafarnagri sheep, on the other hand is found in the sub-tropical hot and humid plains at an altitude of about 250 m. Comparative transcriptomics was used to provide a molecular perspective of the differential adaptation of the two breeds. RNA sequencing data was generated from four biological replicates of the longissimus thoracis muscles from both breeds. The common genes expressed in both breeds were involved in muscle contraction and muscle fibre organization. The most significant pathways enriched in Changthangi muscles were glycogen metabolism, reduction of cytosolic Ca++ levels and NFE2L2 regulating anti-oxidant, while those in Muzzafarnagri were extracellular matrix organization and collagen formation. The hub genes identified in Changthangi were involved in hematopoiesis and HIF signaling pathway, suggesting the molecular acclimatization of Changthangi to the high altitude cold desert of Ladakh. The nodal genes discovered in Muzzafarnagri sheep were associated with the extracellular matrix which accentuates its significance in the development, growth and repair of muscles. The observed transcriptomic differences underscore the morphological and adaptive disparity between the two breeds. The candidate genes and pathways identified in this study will form the basis for future research on adaptation to high altitude and body size in small ruminants.

Prolific breeds of domestic sheep (Ovis aries) are important genetic resources due to their reproductive performance, which is characterized by multiple lambs per birth and out-of-season breeding. However, the lack of a comprehensive understanding of the genetic mechanisms underlying the important reproductive traits, particularly from the evolutionary genomics perspective, has impeded the efficient advancement of sheep breeding. Here, for the first time, by performing RNA-sequencing we built a de novo transcriptome assembly of ovarian and endometrial tissues in European mouflon (Ovis musimon) and performed an mRNA–miRNA integrated expression profiling analysis of the wild species and a highly prolific domestic sheep breed, the Finnsheep. We identified several novel genes with differentially expressed mRNAs (e.g., EREG, INHBA, SPP1, AMH, TDRD5, and ZP2) between the wild and domestic sheep, which are functionally involved in oocyte and follicle development and fertilization, and are significantly (adjusted P-value < 0.05) enriched in the Gene Ontology (GO) terms of various reproductive process, including the regulation of fertilization, oogenesis, ovarian follicle development, and sperm–egg recognition. Additionally, we characterized 58 differentially expressed miRNAs and 210 associated target genes that are essential for the regulation of female reproduction cycles through specific regulatory networks [e.g., (miR-136, miR-374a, miR-9-5p)-(EREG, INHBA)]. Furthermore, our integrated mRNA and miRNA expression profiling analysis elucidated novel direct and indirect miRNA/mRNA causal regulatory relationships related to the reproductive traits of the Ovis species. This study provides in-depth insights into the genomic evolution underlying the reproductive traits of the Ovis species and valuable resources for ovine genomics.

Climate change reduces snowpack, advances snowmelt phenology, drives summer warming, alters growing season precipitation regimes, and consequently modifies vegetation phenology in mountain systems. Elevational migrants track spatial variation in seasonal plant growth by moving between ranges at different elevations during spring, so climate-driven vegetation change may disrupt historic benefits of migration. Elevational migrants can furthermore cope with short-term environmental variability by undertaking brief vertical movements to refugia when sudden adverse conditions arise. We uncover drivers of fine-scale vertical movement variation during upland migration in an endangered alpine specialist, Sierra Nevada bighorn sheep ( Ovis canadensis sierrae ) using a 20-year study of GPS collar data collected from 311 unique individuals. We used integrated step-selection analysis to determine factors that promote vertical movements and drive selection of destinations following vertical movements. Our results reveal that relatively high temperatures consistently drive uphill movements, while precipitation likely drives downhill movements. Furthermore, bighorn select destinations at their peak annual biomass and maximal time since snowmelt. These results indicate that although Sierra Nevada bighorn sheep seek out foraging opportunities related to landscape phenology, they compensate for short-term environmental stressors by undertaking brief up- and downslope vertical movements. Migrants may therefore be impacted by future warming and increased storm frequency or intensity, with shifts in annual migration timing, and fine-scale vertical movement responses to environmental variability.

Growth and reproductive performance traits are important economic indicators for analyzing the overall performance of breeding systems. This study aims to evaluate the comparative performance of two Algerian sheep (Rumbi and Hamra) in terms of growth and reproductive performance, and the effect of factors such as breed, season of birth, mode of birth and age of the mother on this performance in a semi-intensive breeding system. The reproductive performance of 577 Rumbi ewes and 1328 Hamra ewes bred at the Tiaret and Saïda experimental stations respectively, was analyzed using performance monitoring data. Fertility rates for the Rumbi and Hamra breeds of 87.14% and 78.8% respectively were practically similar (p > 0,05). Litter size at birth and weaning was significantly higher in the Hamra breed than in the Rumbi breed (p < 0,05). Weaning mortality was significantly higher in the Hamra breed than in the Rumbi breed, with an average of 22.60% versus 14.94% (p < 0,05). The effect of factors showed that there was a highly significant effect of the mother’s age and season of birth on the reproductive performance of the Hamra and Rumbi breeds with a p < 0.0001 on fertility, litter size at birth, litter size at weaning and fertility. There was a significant effect of the year factor on reproductive performance with p = 0,013 for the Hamra breed and p = 0,031 for the Rumbi breed. The results of this study showed that Rumbi lambs were heavier at birth than Hamra lambs. The values observed were 4,86 kg versus 3,10 kg for the Hamra breed, with a highly significant difference (p < 0,0001), so that the average daily pre-weaning weight gains of Rumbi lambs were higher than those of Hamra lambs, at 0,195 kg/day versus 0,113 kg/day for Hamra lambs, with a high significance (p < 0,0001). The effect of factors showed that there was a significant effect of the mother’s age on the ADGs (0–30), (30–70) and (70–90) of the Hamra and Rumbi breeds with a p = 0,034 and p = 0,02 respectively. There was also a highly significant effect of the birth mode effect on ADGs (0–30), (30–70) and (70–90) only for the Hamra breed with a p = 0,004. The effect of the birth weight on ADGs was not significant for both Hamra and Rumbi breeds with a p > 0,05. According to the findings of this study, the Hamra breed had superior reproductive potential and the Rumbi breed had superior growth. The Hamra breed showed better maternal skills in terms of fertility and prolificacy, while the Rumbi breed showed better lamb growth performance. Consequently, these results could be used for selective sheep breeding, taking into account the random effects of the environment and the potential of each breed.

The study’s objectives were to assess the genetic parameters of reproductive characteristics in Sangsari sheep. A data set of reproductive information with pedigree details from 1995 to 2016 was used. Studied traits were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB), litter mean weight per lamb weaned (LMWLW), total litter weight at birth (TLWB) and total litter weight at weaning (TLWW). Test significance of the environmental factors to be included in the model was conducted using the general linear model procedure of the SAS program. All traits were significantly affected by the year of lambing and ewe age at lambing (P < 0.01). The AI-REML procedure of the Wombat program was used to evaluate genetic parameters. A series of bivariate animal models were employed to calculate genetic (rg) and phenotypic (rp) correlations between traits. The total least square means ± standard error of LSB and LSW were 1.04 ± 0.05 and 0.96 ± 0.03, while LMWLB, LMWLW, TLWB, and TLWW were 3.12 ± 0.08, 15.40 ± 0.13, 3.28 ± 0.04, and 19.31 ± 0.16 kg, respectively. The estimates of h2 were relatively low (P < 0.01) and ranged from 0.063 ± 0.028 for LSW to 0.181 ± 0.063 for TLWW. Repeatability estimates varied from 0.101 for LSW to 0.241 for TLWW. The sire service effects for LMWLB, TLWB, and TLWW were 0.012 ± 0.004, 0.023 ± 0.006, and 0.039 ± 0.009, respectively. The traits studied showed a greater magnitude of genetic correlation than phenotypic correlation, with values ranging from − 0.59 (LSB-LMWLB) to 0.87 (LMWLB-TLWB). It appears that focusing on TLWW for selection could result in more significant improvements in the reproductive performance of Sangsari ewes.

This study aimed to evaluate the intake, performance, quality, and fatty acids (FA) composition of the meat of three Nigerian sheep breeds (Balami, Uda, and Yankasa) fed two different hays, Brachiaria decumbens or Digitaria smutsii . A total of sixty sheep, twenty from each breed, Balami, Uda, and Yankasa, were used, with average body weights of 24.7 ± 3.5 kg, 25.5 ± 3.6 kg, and 25.5 ± 3.5 kg, respectively. The sheep were arranged in a factorial 2 (hay types) × 3 (breeds) design within a completely randomized setup, totalling ten experimental units per treatment. There was no significant ( p  > 0.05) interaction effect between breed and hay type on any variables. Sheep-fed D. smutsii hay presented higher ( p  ≤ 0.05) DM intake from the concentrate, hay, total feed, final BW, ADG, intramuscular fat, and FA contents than sheep-fed B. decumbens , except for 18:1n-9, where sheep fed B. decumbens presented higher ( p  ≤ 0.05) concentration. Balami sheep presented higher ( p  ≤ 0.05) total weight gain than the Uda breed and once performed better than the Yankasa breed, without difference ( p  > 0.05) to feed efficiency. Longissimus lumborum of the Yankasa breed presented lower concentrations ( p  ≤ 0.05) of total polyunsaturated FA (PUFA) than Balami and Uda sheep. The content of n-3 and n-6 PUFA (linolenic, EPA, DPA, and DHA), n-6/n-3 ratio, and EPA + DHA were higher in the Balami sheep than in the Uda sheep. Balami breed had the highest carcass weight and meat protein content but had a lower ( p  ≤ 0.05) moisture content than other breeds. Uda and Yankasa sheep presented similar moisture content ( p  ≤ 0.05). However, the carcass weight, protein, and fat content of the longissimus lumborum were higher ( p  ≤ 0.05) in Uda compared to Yankasa sheep. Nigerian sheep fed D. smutsii hay compared to B. decumbens hay to provide greater DM intake, improving fattening and meat fat and increasing all fatty acids in the longissimus lumborum . Balami breed presented greater DM intake, performance, and carcass weight, and consequently higher intramuscular fat deposition and concentration of most fatty acids in the longissimus lumborum than the breeds Uda and Yankasa.

This study evaluated growth and reproductive traits in two sheep breeds in Türkiye, Akkaraman (AKK) and Central Anatolian Merino (CAM), with a focus on the impact of non‐genetic factors. Data were analysed from 21,414 AKK and 20,099 CAM lambs for birth weight (BW) and 27,528 AKK and 24,639 CAM lambs for weaning weight (WW), average daily weight gain (ADWG) and Kleiber ratio (KR) using a linear mixed model. AKK lambs showed a significantly higher mean BW (4.19 ± 0.01 kg) than CAM lambs (4.02 ± 0.01 kg) (p < 0.001), whereas CAM lambs had significantly higher WW, ADWG and KR (p < 0.001 for each trait). Fixed effects of sex, birth type, dam age, birth year, herd size and season significantly influenced all growth traits (p < 0.05). Male lambs demonstrated higher BW, WW, ADWG and KR than females (p < 0.001), and single‐born lambs had significantly higher BW and WW than twins (p < 0.001). Dam age also influenced all growth traits, with lambs from younger dams tending to be heavier (p < 0.001). In terms of survival, AKK lambs exhibited a significantly higher survival rate (93.85%) than CAM lambs (89.50%) (p < 0.001). Conception rates were similar for both breeds (92.9% for AKK and 92.3% for CAM), whereas CAM lambs showed higher fecundity and litter size. These findings underscore the breed differences in growth and reproductive traits and highlight the importance of considering non‐genetic factors to inform breed‐specific management practices aimed at optimizing productivity. This study evaluates growth and reproductive traits in Akkaraman (AKK) and Central Anatolian Merino (CAM) sheep in Türkiye. AKK lambs showed higher birth weights but lower weaning weights and growth rates compared to CAM lambs. Significant non‐genetic factors, such as sex, birth type and dam age, influenced these traits. AKK lambs exhibited higher survival rates, while CAM demonstrated greater fecundity. These findings underscore the importance of breed‐specific management practices to optimize productivity.

Background The comprehensive understanding of microRNAs (miRNAs) in sheep milk during various lactation periods and their impact on milk yield and composition remains limited. Objectives 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. Methods 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. Results 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. Conclusions 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. 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. Notably, 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. oar‐miR‐21‐5p demonstrated a significant fold change exclusively in peak lactation compared to Akkaraman and Awassi ewes.

The increasing global demand for food and the strong effect of climate change have forced animal science to advance regarding new methods of selection in search of more efficient animals in production systems. Feed consumption represents more than 70% of the costs of sheep farms, and more efficient animals can increase the farmers’ profitability. One of the main measures of feed efficiency is estimated residual feed intake (RFI), created in 1963 by Robert Koch for estimation in cattle and later adapted for sheep. Animals with negative RFI values (RFI-) are more efficient than animals with positive values (RFI+), with influence on the variables of performance, carcass quality and production of enteric gases. The RFI is the most common and accepted metric of the feed efficiency trait for genetic selection, since it is independent of growth traits, unlike the feed conversion ratio. The purpose of this review article was to present updated literature information on the relationship of RFI estimates with performance measures, molecular markers, greenhouse gas production and feed efficiency, the technical aspects and physiological basis of metabolic in sheep.

This study aimed to estimate genetic parameters, including heritability and repeatability, for milk yield and prolificacy in sheep. It included 3682 records from 1837 ewes across various breeds: Awassi, Assaf, and Awassi x Assaf crosses, two Awassi lines: Improved Awassi, AFEC Awassi. The study measured total milk yield (TMY), yield up to 120 days (TMY120), and yield up to 150 days (TMY150), alongside reproductive traits: litter size (LS), number of lambs born alive (NLBA), and lambing interval (LI). The analysis utilized a mixed model and the REML procedure to estimate genetic parameters. Results indicated that litter size (LS) had no significant impact on milk traits, whereas breed, location, ewe parity, and lambing season showed significant effects. Lactation length also significantly influenced TMY. For reproductive traits, treatment was significant for NLBA, with location associated with breed, parity, and season affecting all traits. Heritability estimates for TMY ranged from 0.00 in Awassi x Assaf crosses to 0.11 in Awassi, and for TMY120 and TMY150, from 0.00 in Awassi x Assaf crosses to 0.16 in Awassi. Estimates for LS and NLBA varied similarly. The heritability for LI was 0.03 in Awassi and zero in other breeds and crosses. The findings suggest that in the northern West Bank regions of Nablus and Jenin, Assaf or Awassi x Assaf breeds are preferable. The study underscores the importance of comprehensive performance and pedigree recording for effective sheep farm management.