β-casein is a primary protein in milk, and its variants have been associated with changes in the protein content of bovine milk. However, there has been little research focused on the effects of β-casein variants on milk metabolites. In the present study, dairy cows producing milk with β-casein variant A1/A1 (A1), A2/A2 (A2), and their heterozygote A1/A2 (A12) were screened by a high-resolution melting method. Individual milk samples were then collected from each of the cows, and the milk metabolites were separated and analyzed using nuclear magnetic resonance spectroscopy- and liquid-chromatography mass spectrometry-based metabolomics techniques. Differences in metabolites among the variant groups were evaluated by multivariate statistical analysis. The relative abundances of methionine, proline, and α-lactose were the highest in β-casein variant A2 milk, whereas choline, glycine, citric acid, and cyclic adenosine monophosphate (cAMP) showed the highest abundances in variant A1 milk. Metabolic pathways analysis indicated that the differential metabolites between variants A1 and A2 were involved in pantothenate and coenzyme A biosynthesis, butanoate metabolism, and valine, leucine, and isoleucine biosynthesis. Our results reveal the differences in milk metabolites among the β-casein variants A1, A2, and the heterozygote. These findings, thus, provide novel insights into the effects of β-casein variants on milk metabolites, facilitating further research into the mechanism of the biosynthesis of milk components in the mammary gland and the potential physiological function of milk associated with β-casein variants.

• Proteomics and metabolomics detected mare milk products adulteration down to 0.1%. • Several proteins of osteopontin identified mare milk products adulteration. • Several metabolites of biotin verified the authenticity of mare milk products. • Specific biomarkers for adulteration identification were influenced by processing.

The aim of this study was to assess the impact of varying proportions (5–20%) of hydroponic wheat sprouts in the diet of growing four-month-old Hu ewes on their productive performance, metabolic profiles, rumen fermentation, and alterations in microflora. Compared with the control group (CON), the optimum final weight of ewes has been presented in the group of substitution 15% (S15) of the basal diet with hydroponic wheat sprouts. Furthermore, 1–30 d the average daily gain (ADG), 31–60 d ADG, and average feed intake were both significantly improved in S15 compared with CON (p < 0.05). Feeding hydroponic wheat sprouts can significantly increase high-density lipoprotein and interleukin-2 (p < 0.05) accompanied by the numerical increase of the content of interferon-γ, suggesting its positive effect on ewes’ health and immune systems. In this process, it is noteworthy that feeding hydroponic wheat sprouts results in an increase in relative abundance of Olsenella, Limosilactobacillus, Shuttleworthia, and Prevotella_7, and a decrease in relative abundance of Succinimonas, Pseudobutyrivibrio, and Anaerovibrio in the rumen of growing ewes. It implies that the response of rumen microflora adapted to the change of dietary ingredients, as well as the relationship between rumen microflora changes and the improvement of productive performance and immune system in growing ewes. Considering the usage cost and application effect, S15 of the basal diet with hydroponic wheat sprouts could be the appropriate application solution for growing ewes.

Milk harbors a diverse array of microorganisms; however, the current understanding of the microbial diversity in raw milk from specific geographical origins and milk types remains unclear. To address this knowledge gap, this study employed single-molecule real-time sequencing to analyze the differences in microbial communities across various farms and milk types from different regions, specifically by examining the microbial diversity in Holstein cow milk samples from farms situated in both adjacent and distant regions, and comparing the microbial diversity between Holstein cow milk and non-bovine milk from farms in adjacent regions. The results demonstrated that several genera, such as Lactiplantibacillus , Pseudomonas , Acinetobacter , and Chryseobacterium , exhibited significant differences in Holstein cow milk from adjacent regions. Additionally, genera like Lactiplantibacillus and Chryseobacterium consistently showed substantial variation in Holstein cow milk across distant regions. At the species level, Lactiplantibacillus plantarum , Pseudomonas lurida , and Haloanella gallinarum displayed significant variations in Holstein cow milk from adjacent regions, while Lactiplantibacillus plantarum and Chryseobacterium carnipullorum were significantly more prevalent in distant regions. The bacterial diversity does not have a clear relationship with the geographic proximity of farms, a finding that is consistent with the results of the principal coordinates analysis. Moreover, milk type had a pronounced impact on microbial diversity, with species such as Acinetobacter johnsonii , Pseudomonas fragi , Enterobacter ludwigii , Achromobacter arsenitoxydans , and Leuconostoc mesenteroides exhibiting substantial variations across different milk types. Furthermore, 22 species of lactic acid bacteria were identified in the studied milk samples. Notably, Holstein, donkey, and camel milk exhibited higher lactic acid bacteria diversity compared to buffalo and horse milk. Among these, Lactiplantibacillus plantarum was significantly more abundant in Holstein cow milk, while Lactobacillus helveticus and Leuconostoc mesenteroides were the predominant beneficial species in donkey and camel milk. IMPORTANCE: The data generated through this research present invaluable insights into the intricate microbial ecosystems inhabiting both Holstein and non-bovine milk varieties. These novel findings significantly advance our knowledge and approach toward understanding and managing microorganisms within milk, thereby bolstering their efficient utilization and facilitating the design of enhanced strategies for their prevention and control. This research not only sheds light on the diversity and dynamics of microbial communities in different milk types but also paves the way for more targeted interventions to ensure milk safety and quality across different production systems.

This study aims to explore the impact of adding sodium acetate and sodium butyrate on the composition, blood biochemical parameters, and volatile flavor compounds of lactating mares’ milk. By assessing the influence of these additives on milk flavor enhancement, the findings provide scientific evidence for optimizing flavor characteristics and offer new strategies for improving the sensory attributes of mare milk products. Eighteen lactating Yili mares were randomly assigned to three groups: a control group, a sodium acetate group (85 mg/kg·BM⁻¹), and a sodium butyrate group (85 mg/kg·BM⁻¹). The experiment lasted 90 days, with milk yield recorded on days 0, 30, 60, and 90. Milk samples were collected on day 60 (peak lactation) for compositional analysis, and GC-IMS was employed to identify and quantify volatile compounds. Additionally, blood samples were drawn from the jugular vein before morning feeding on day 60 using heparinized tubes to assess key biochemical markers, including glucose, triglycerides, total cholesterol, and urea. The results revealed the following findings: (1) Milk yield and composition: The addition of sodium acetate and sodium butyrate had no significant effect on milk yield. However, both treatment groups exhibited significantly or extremely significantly higher milk fat content compared to the control group, whereas milk protein and lactose levels remained largely unchanged. (2) Blood biochemical indicators: The sodium butyrate group showed an extremely significant increase in urea levels compared to the sodium acetate and control groups. Glucose levels in the sodium acetate group were also significantly higher than in the control group. Moreover, triglyceride levels were markedly elevated in the sodium butyrate group compared to the sodium acetate group, while total bilirubin concentrations were significantly higher in the sodium acetate group than in the control group. (3) Volatile compounds: The addition of these additives led to a significant increase in the diversity and concentration of volatile compounds in mare milk. Notably, esters, aldehydes, and ketones showed substantial enrichment in both treatment groups. The relative abundance of esters such as butyl acetate, L-lactic acid ethyl ester, 1-pentene-3-ol, pentanol, and 3-pentanone increased, alongside a significant rise in aldehydes and ketones, including 2-heptenal and 3-pentanone. In conclusion, sodium acetate and sodium butyrate enhance milk flavor by modulating milk composition and metabolic parameters, providing a scientific foundation for improving the quality of mare milk products.