| Pengbo sheep is a major livestock breed in the Tibet region and is widely raised due to its stable genetic and production performance.The husbandry of Pengbo lambs before weaning is the key to improving breeding efficiency.Milk is the main source of nutrition for lambs before weaning and is crucial for establishing the gastrointestinal microbiota and improving immune function during the early stage of their lives.Therefore,the quality of milk has a direct impact on lamb breeding performance.The nutritional composition of milk and milk microbiota change significantly during lactation to meet the nutritional needs of lambs during different physiological and developmental stages.Based on this,this study systematically investigated the nutritional composition and microbial succession of milk in the early lactation period of Pengbo sheep,providing a theoretical basis for improving the breeding performance of offspring from the perspective of maternal-offspring integration.The study also compared and analyzed the nutritional composition and microbial succession of milk under the same lactation days for Tibetan goats in the same habitat,aiming at providing individualized strategies for lamb breeding before weaning and the development of milk replacers.The main results obtained from the study are as follows:1.The nutritional composition,somatic cell count,and immunoglobulin(IgA,IgM,and IgG)content of the milk of Pengbo sheep at seven lactation stages,D0,D3,D7,D14,D28,D42,and D56,were analyzed.It was found that the nutritional composition of Pengbo sheep milk decreased with increasing lactation period.The content of fat,protein,non-fat milk solids,and casein in milk showed changes in two stages,D0-D7 and D14-D56.However,the immunoglobulin content was relatively stable during lactation,and there was a complex correlation between the nutritional components of milk.2.The results of the 16 S rRNA of Pengbo sheep milk showed that with increasing lactation period,the α diversity of milk microbiota increased,and the milk microbiota community underwent significant changes(P < 0.001).The relative abundance of core bacterial phyla(such as Proteobacteria,Firmicutes,Actinobacteriota,and Bacteroidota)and genera(such as Ralstonia,Lactobacillus,Streptomyces,Acinetobacter,Weissella,and Leuconostoc)in milk was significantly influenced by lactation period.Based on the age differences of the milk microbiota,milk can be classified into three types,D0-D7,D14-D28,and D42-D56.Furthermore,with increasing lactation period,the ratio of Firmicutes to Bacteroidota and the ratio of aerobic bacteria to anaerobic bacteria in milk significantly decreased(P < 0.01).The results of multiple comparisons showed that the relative abundance of some potential probiotics in Pengbo sheep milk increased with increasing lactation peroid(P < 0.01).In addition,there were specific microbiota in colostrum of Pengbo sheep,mainly Pediococcus,Saccharopolyspora,and Lactococcus,with a high Aerobic and Gram-positive phenotype and low Potential pathogenicity.The correlation analysis between the nutritional components of milk and milk microbiota showed a strong correlation between the abundance succession of milk microbiota in Pengbo sheep and the changes in milk nutritional composition.3.The nutritional components and microbial composition of milk are influenced not only by the lactation stage but also by the species.Therefore,this study compared and analyzed the succession patterns of nutritional components and microbial data in the milk of Tibetan sheep and goats at the same lactation days(D0,D7,D14,D28,and D56),using data from both species.The results showed that there were significant differences(P < 0.05)in the nutritional components and microbial composition between the milk of sheep and goats.In addition,the core microbial species in the milk of both sheep and goats,such as Acidobacteriota,Lactobacillus,and Corynebacterium,exhibited consistent changes with lactation days across both species.Overall,this study systematically analyzed the nutritional components and microbial succession patterns in the milk of Tibetan Pengbo sheep from D0 to D56,and compared and analyzed the composition and succession patterns of the core milk microbiota in Tibetan sheep and goats at the same lactation days in the same habitat.This provides a theoretical basis for improving the breeding effect of offspring from the perspective of mother-offspring integration,and aims to provide personalized additive solutions for pre-weaning milk powder for lambs. |
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