Consumers are increasingly demanding higher-quality mutton. Crossbreeding has been recognized as an effective means to improve meat quality. However, the phenomenon underlying these molecular system mechanisms remains largely unidentified. In this study, 48 male lambs aged 3 months were selected, including ♂ Hu sheep × ♀ Hu (HH, n = 16), ♂ Polled Dorset × ♀ Hu sheep F₁ hybrid lambs (DH, n = 16), and ♂ Southdown × ♀ Hu sheep (SH, n = 16) F₁ hybrid lambs, and raised in a single pen under the same nutritional and management conditions for 95 days. Then, seven sheep close to the average weight of the group were selected and fasted for 12 h prior to slaughter. By comparing the muscle fiber characteristics of the Longissimus dorsi of the three groups of sheep, and through transcriptomic and metabolomic analyses, we revealed molecular differences in the meat quality of Hu sheep crossbred with different parent breeds. The results of this study showed that muscle fiber diameter and cross-sectional area were significantly greater in the DH group than in the HH group, and collagen fiber content in the DH group was also significantly higher than in the HH group (p < 0.05). A total of 163 differential genes and 823 differential metabolites were identified in the three groups, most of which were related to muscle development and lipid metabolism. These included the AMPK signaling pathway, the PI3K-Akt signaling pathway, glycerophospholipid metabolism, and the related genes EFHB, PER3, and PPARGC1A. The results of this study offer valuable insights into the molecular mechanisms underlying the impact of crossbreeding on meat quality and provide a theoretical foundation for sheep crossbreed production.

This study aims to compare the accuracy of genomic estimated breeding values (GEBV) estimated using a genomic best linear unbiased prediction (GBLUP) method and GEBV estimates incorporating prior marker information from a genome-wide association study (GWAS) for the weaning weight trait in highland Merino sheep. The objective is to provide theoretical and technical support for improving the accuracy of genomic selection. The study used a population of 1007 highland Merino ewes, with the weaning weight at 3 months as the target trait. The population was randomly divided into two groups. The first group was used for GWAS analysis to identify significant markers, and the top 5%, top 10%, top 15%, and top 20% markers were selected as prior marker information. The second group was used to estimate genetic parameters and compare the accuracy of GEBV predictions using different prior marker information. The accuracy was obtained using a five-fold cross-validation. Finally, both groups were subjected to cross-validation. The study’s findings revealed that the heritability of the weaning weight trait, as calculated using the GBLUP model, ranged from 0.122 to 0.394, with corresponding prediction accuracies falling between 0.075 and 0.228. By incorporating prior marker information from GWAS, the heritability was enhanced to a range of 0.125 to 0.407. The inclusion of the top 5% to top 20% significant SNPs from GWAS results as prior information into GS showed potential for improving the accuracy of predicting genomic breeding value.

This study was conducted to investigate potential regulatory mechanisms of hybridization increased the meat production performance in sheep. Thirty-six 3-month-old male lambs of Suffolk sheep (SFK, n = 12), Hu sheep (HH, n = 12), and their F₁ hybrids (SH, n = 12) were selected and raised in individual pens under identical nutritional supply and husbandry management regimes over a 95-day (including a 15-day pre-trial period) experimental period. At the end of the feeding trial, six sheep closest to the average body weight were selected from each group for the subsequent trial, involving the collection of Longissimus dorsi samples and the determination of production performance, muscle fiber characteristic and transcriptomic and metabolomic analysis. The results showed that the SH sheep had significantly higher pre-slaughter live weight and carcass weight than the HH sheep, while lower than those of the SFK sheep (p < 0.05). The muscle fiber density of the SH group was significantly higher than that of the parental groups, while the muscle fiber diameter and cross-sectional area were significantly smaller (p < 0.05). The collagen fiber content of the SH group was intermediate between the two parental groups and significantly higher than that of the SFK group (p < 0.05). Transcriptomic analysis identified 2920 differentially expressed genes (DEGs), which were mainly enriched in the AMPK, PI3K-Akt, and PPAR signaling pathways. Metabolomic analysis detected 1617 differential metabolites (DMs), which were enriched in the fatty acid degradation and steroid hormone biosynthesis pathways. Integrated analysis revealed that core genes SESN3 and metabolites (malate, testosterone) enhance energy supply capacity through AMPK pathway, thereby promoting muscle fiber proliferation and increasing meat yield in the hybrid sheep. In conclusion, the heterosis of the SH group originates from the remodeling of muscle fiber structure and the synergistic regulation of related pathways, which provides a theoretical basis for sheep crossbreeding.

With the increasing consumer demand for high-quality lamb, crossbreeding has become a key technology for improving the production performance and meat quality of sheep. To evaluate the meat quality advantages and characteristics of Suffolk (SFK) and Hu sheep (HH) and their F₁ crossbreds (SH), thirty-six 3-month-old male lambs of SFK (n = 12), HH (n = 12), and SH (n = 12) were selected and raised in individual pens under the same nutritional and management conditions. After standardized feeding until 6 months of age, the Longissimus dorsi muscle was collected to determine meat quality traits, amino acid and fatty acid profiles, and volatile flavor compounds. The results indicated that the L*, a* and b* values of the SH group were significantly lower than those of the parental breeds (p < 0.05), with tenderness being intermediate between the two parent breeds. Notably, drip loss and cooking loss were significantly lower in the SH group (p < 0.05), indicating superior water-holding capacity. In terms of amino acid profiles, the contents of non-essential amino acids (NEAAs) and sweet-tasting amino acids in the SH group were significantly higher than those of the parent breeds (p < 0.05), with the overall profile meeting the FAO/WHO ideal protein pattern. Analysis of fatty acid profiles revealed that the SH group had significantly lower total saturated fatty acids (SFAs) (p < 0.05) and significantly higher levels of functional fatty acids (such as CLA), resulting in a significantly higher UFAs (unsaturated fatty acids)/SFAs (saturated fatty acids) ratio (p < 0.05) and superior nutritional value of fat. Furthermore, 32 volatile flavor compounds were detected in the SH group; among them, key aroma-active compounds such as isoamyl formate, 3-methyl-1-butanol, and acetoin were significantly higher than in the parental breeds (p < 0.05), contributing to a unique flavor profile. Consequently, this study systematically reveals the advantages of Suffolk × Hu F₁ crossbreds in terms of meat quality, nutritional value, and flavor characteristics, providing fundamental data for the optimization of crossbreeding systems, breeding selection, and the quality improvement of sheep meat products.

Objective: Although Hu sheep are renowned for their high fecundity, the multi-tissue regulatory networks governing spermatogenesis, particularly within the hypothalamic–pituitary–testicular (HPT) axis, remain poorly understood. This study aimed to elucidate these mechanisms by performing a comparative proteomic analysis of the HPT axis in Hu sheep and three other breeds. Methods: We utilized data-independent acquisition (DIA) proteomics to analyze hypothalamic, pituitary, and testis tissues from 36 samples across four breeds. The experimental workflow included protein extraction, enzymatic digestion, LC-MS/MS, and subsequent bioinformatic analyses, complemented by histological examination. Results: Hu sheep exhibited accelerated testicular development and an earlier onset of spermatogenesis. Comprehensive proteomic profiling identified a total of 10,528 proteins, with 771 differentially expressed proteins (DEPs) detected in the testis. These testicular DEPs were significantly enriched in pathways related to spermatogenesis, the blood–testis barrier, and steroid hormone biosynthesis. Notably, the cAMP signaling pathway was consistently enriched across all three tissues, underscoring its pivotal role in regulating spermatogenesis. Protein–protein interaction (PPI) network analysis further highlighted hub proteins, such as MET, suggesting their potential involvement in somatic cell functions and the spermatogenic microenvironment. Key findings were validated by Western blot analysis. Conclusion: This study is the first multi-tissue proteomic investigation proposing a model in which the high reproductive performance of Hu sheep is potentially linked to the efficient, coordinated regulation of spermatogenesis-related proteins and signaling pathways—particularly in the testis. These findings offer novel insights into the molecular mechanisms of male reproduction in sheep and identify potential targets for future research and breeding applications.

This study compared the growth performance, rumen fermentation patterns, and microbial community structure between three-way crossbred (Poll Dorset × Southdown × Hu, TNH) and purebred Hu (HH) sheep. A total of 75 male lambs (HH: n = 35; TNH: n = 40) with comparable birth dates were selected. After a 56-day suckling period, all lambs underwent an 84-day standardized fattening protocol with a uniform diet. Growth indicators were monitored, and rumen fluid was collected using an oral ruminal sampler for the determination of volatile fatty acids (VFAs) and 16S rRNA sequencing. TNH sheep demonstrated significantly superior growth performance, including higher body weight (BW), average daily gain (ADG) and Kleiber ratio (KR). TNH sheep exhibited an acetate-type pattern with higher acetate, butyrate, total VFAs, and acetate/propionate ratio (A/P), whereas HH sheep showed a propionate-type fermentation pattern with higher branched-chain VFAs. Bacteroidetes and Firmicutes were the dominant core microbiota in both the TNH and HH groups. However, the higher species richness and diversity in the TNH sheep was observed, and harbored a distinct community structure featuring Prevotella as the predominant genus. Shuttleworthia , Olsenella , and Syntrophococcus were unique to HH sheep, whereas Prevotellaceae_UCG_003 was specifically enriched in the TNH sheep. Metabolic pathways, carbon metabolism, and glycolysis/gluconeogenesis were predominantly enriched in TNH sheep, whereas biosynthesis of amino acids and ABC transporters were more abundant in HH sheep. These findings demonstrate that crossbreeding can optimize host metabolism and production performance by modulating rumen VFA dynamics and microbiota structure.