This study explored the polymorphism of the leucine aminopeptidase (LAP3) gene and its relationship with milk quality characteristics in Gannan yak. A cohort of 162 Gannan yak was genotyped utilizing the Illumina Yak cGPS 7K BeadChip, and the identified single nucleotide polymorphisms (SNPs) were evaluated for their association with milk protein, casein, lactose, and fat concentrations. The results showed that four SNPs (g.4494G > A, g.5919A > G, g.8033G > C, and g.15,615A > G) in the LAP3 gene exhibited polymorphism with information content values of 0.267, 0.267, 0.293, and 0.114, respectively. All four SNPs were in Hardy–Weinberg equilibrium (p > 0.05). The g.4494G > A and g.5919A > G SNPs were significantly associated with protein content (p < 0.05), with homozygous genotypes showing significantly higher protein content than heterozygous genotypes (p < 0.05). The g.8033G > C SNP was significantly associated with casein content, protein content, non-fat solids, and acidity (p < 0.05), with the CC genotype having significantly higher casein, protein, and non-fat solids content than the GG and GC genotypes (p < 0.05). The g.15,615A > G SNP was significantly associated with average fat globule diameter (p < 0.05). In general, the mutations within the LAP3 gene demonstrated a positive impact on milk quality traits in Gannan yak, with mutated genotypes correlating with enhanced milk quality. These results indicate that the LAP3 gene could be a significant or candidate gene affecting milk quality traits in Gannan yak and offer potential genetic markers for molecular breeding programs in this species.

The morphogenesis of hair follicle structure is accompanied by the differentiation of skin tissue. Mammalian coats are produced by hair follicles. The formation of hair follicles requires signal transmission between the epidermis and dermis. However, knowledge of the transcriptional regulatory mechanism is still lacking. We used single-cell RNA sequencing to obtain 26,573 single cells from the scapular skin of yaks at hair follicle telogen and anagen stages. With the help of known reference marker genes, 11 main cell types were identified. In addition, we further analyzed the DP cell and dermal fibroblast lineages, drew a single-cell map of the DP cell and dermal fibroblast lineages, and elaborated the key genes, signals, and functions involved in cell fate decision making. The results of this study provide a very valuable resource for the analysis of the heterogeneity of DP cells and dermal fibroblasts in the skin and provide a powerful theoretical reference for further exploring the diversity of hair follicle cell types and hair follicle morphogenesis.

The colon plays a crucial role in energy metabolism and intestinal health of ruminants during various physiological stages. Plateau ruminants have long been subjected to extreme environments characterized by hypoxia, cold, and nutritional scarcity, which makes their dependence on energy metabolism particularly pronounced. However, existing research on the regulatory effects of dietary energy levels on the colonic function of plateau ruminants is still quite limited. This study involved 60 healthy male Pamir yaks with consistent body conditions, which were randomly divided into three groups: a low-energy diet group (YG, Neg 1.53 MJ/kg), a medium-energy diet group (QG, Neg 2.12 MJ/kg), and a high-energy diet group (RG, Neg 2.69 MJ/kg). Each yak was provided with 5 kg of mixed feed daily over a 170-day feeding trial. The results indicated that a high-energy diet enhanced growth performance in yaks (p < 0.05). However, it also induced local colonic inflammation, decreased levels of immune factors (IgA, IgG, and IL-10), and increased the abundance of potentially pathogenic bacteria, such as Klebsiella and Campylobacter (p < 0.05). Conversely, a medium-energy diet fostered the proliferation of beneficial bacteria such as Bradymonadales, Parabacteroides, and Mogibacterium (p < 0.05), and preserved immune homeostasis. Additionally, multi-omics analysis revealed that the QG group was significantly enriched in key metabolic pathways, including pyruvate metabolism and glycine, serine, and threonine metabolism and panto-thenate and CoA biosynthesis pathways, among others (p < 0.05), demonstrating a synergistic regulatory effect among the microbiome, metabolism, and host. In summary, a moderate-energy diet can promote the proliferation of beneficial bacteria in the extreme environment of the plateau. By regulating pathways such as Amino acid, Nucleotide, and Lipid metabolism, it coordinates the expression of key host genes and metabolite levels, effectively balancing immune signals and energy metabolism. This interaction establishes a beneficial microbial-metabolism-host pattern that supports colon health.

Fatty acid synthase (FAS) is a fundamental metabolic enzyme that catalyzes the synthesis of endogenous fatty acids; TACR3, also known as tachykinin receptor 3 or NK3R, is an important G-protein-coupled receptor that is primarily responsible for responding to neuropeptides such as neurokinin B (NKB) and plays a crucial role in embryonic development, organ formation, and cell differentiation. This study aimed to explore the association between the single-nucleotide polymorphisms (SNPs) of the FAS and TACR3 genes and the milk quality of Gannan yak and to determine them as potential molecular marker loci for the milk quality of yaks. The genotyping of 162 Gannan yaks was performed using liquid-phase chip technology. Association analyses were conducted between the obtained SNP loci genotypes and milk composition traits, including milk protein, casein, non-fat solids, and acidity. Comparative sequence analysis of two genes (FAS and TACR3) across multiple species revealed that the yak FAS gene exhibited the highest homology with Bos taurus and Bos indicus, while the yak TACR3 gene showed the greatest sequence similarity to Bos taurus. Hardy–Weinberg equilibrium tests were performed on four SNP loci, and the equilibrium indices of the four loci were 0.799, 0.368, 0.689, and 0.948 (p > 0.05), indicating that all of these loci are in Hardy–Weinberg equilibrium state. g.13,276T>C (FAS) was significantly correlated with lactose content traits (p < 0.05); g.74,382C>G (FAS) was significantly correlated with casein, protein, total solids, non-fat solids, and acidity traits (p < 0.05); g.40,529A>G (TACR3) was significantly correlated with protein, non-fat solids, citric acid, and acidity traits (p < 0.05). The influence of g.40,555C>T (TACR3) on these traits did not reach a significant level (p > 0.05). This study suggests that two genes can serve as potential candidate genes affecting the quality of Gannan yak milk, providing reference genes for improving the quality of Gannan yak milk.

The yak is a vital livestock resource on the Qinghai–Tibet Plateau, renowned for its strong disease resistance and high-quality meat. However, various diseases pose significant threats to its health and lead to substantial economic losses. Current feeding management practices, along with available drugs and vaccines, have demonstrated limited effectiveness in preventing and controlling infectious diseases. Additionally, challenges such as drug resistance and the safety of animal products persist. Therefore, enhancing the disease-resistant breeding capacity of yaks is crucial. In this study, we examined 192 yaks by measuring the concentrations of 10 immune indicators in serum by using the ELISA method and conducting whole-genome resequencing, which identified 19,182,942 SNP loci. Through genome-wide association analysis, we detected 323 significant SNPs located near or within 125 candidate genes, most of which are associated with disease and significantly enriched in the TGF-β signaling pathway. Overall, our study identified a series of novel variants and candidate genes associated with disease resistance traits in yaks, providing important information for the molecular breeding of disease resistance in yaks. These results not only contribute to a deeper understanding of the function of disease resistance genes in yaks but also hold great potential for accelerating precision disease resistance breeding in yaks.