Comparative study of serum lipidomics, and milk microbiota and metabolomics in long-lived dairy cows with different persistent production capacities

Extending the lifespan of dairy cows is crucial for achieving environmentally sustainable livestock production. Understanding the unique physiological characteristics of long-lived cows with persistent productivity provides critical insights into extending the productive lifespan of dairy cows. In this study, untargeted lipidomics, 16S rRNA sequencing, and untargeted metabolomics were applied to evaluate the blood lipid profile, milk microbiome composition, and milk metabolome of long-lived, high-yielding cows (LH) and long-lived, low-yielding cows (LL). The results demonstrated that in the serum of LH cows, the levels of coenzyme (Co), bis-methyl phosphatidic acid (BisMePA), lysodimethylphosphatidylethanolamine (LdMePE), monolysocardiolipin (MLCL), ceramide (Cer), dihexosylceramides (Hex2Cer), and sphingomyelin (SM) were elevated. However, the levels of triglyceride (TG), phosphatidylglycerol (PG), ceramide phosphoethanolamines (CerPE), and trihexosylceramides (Hex3Cer) were decreased. In addition, omega-3 polyunsaturated fatty acids (PUFAs) ether-linked phospholipids (PUFA-ePLs) decreased. Conversely, omega-3 PUFA phospholipids (PUFA-PLs) increased. No significant differences were observed in the alpha- and beta-diversity of milk microbiota between the two groups. However, the community assembly processes differed significantly. The LH group exhibited significantly higher levels of homogeneous selection, drift(and others). In contrast, dispersal limitation, homogeneous dispersal, and heterogeneous selection were significantly lower. In the milk of LH cows, UCG-005, Prevotellaceae UCG-003, Ruminococcus, unclassified f Oscillospiraceae, norank f Fodinicurvataceae, and unclassified f Ruminococcaceae were significantly enriched. The bacterial functions of protein digestion and absorption and N-glycan biosynthesis were significantly enriched in the LH group, while thyroid hormone synthesis and pathogenic Escherichia coli infection were significantly enriched in the LL group. Additionally, the milk of LH cows exhibited elevated levels of omega-3 PUFAs, including PE(20:5/0:0), LysoPC(20:5(5Z,8Z,11Z,14Z,17Z)/0:0), LysoPE(0:0/20:5(5Z,8Z,11Z,14Z,17Z)), and PE(22:5/0:0). This study hypothesized that the enhanced involvement of omega-3 PUFA-ePL in antioxidant processes in the blood of LH cows may contribute to the more readily utilizable omega-3 PUFA-PLs. The elevated levels of bioavailable eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may reduce the susceptibility of LH cows to adverse health outcomes, declines in reproductive performance, and involuntary culling. Furthermore, the increased availability of omega-3 PUFAs for mammary gland utilization may enhance the concentrations of specific omega-3 PUFAs in milk, thereby potentially benefiting the milk microbiota and enhancing nutritional value of milk fatty acids in LH cows.