Developmental changes of nutrient digestion in young lambs are influenced by weaning and associated with intestinal microbiota

Understanding the effects of weaning on the changes of digestive function could help to design efficient intervention strategies for promoting the development of the lamb during the early stages of life. In this study, 24 lambs were divided into two groups (control group, lambs were not weaned; and weaning group, lambs were weaned at 21 days of age). The growth, nutrient digestion, gastrointestinal enzyme activity, plasma biochemical indicators, and intestinal microbiota at 7-49 days were determined, as well as the impact of early weaning. The nutrient digestion changed rapidly with age, especially at 14-28 days (p < 0.05). Weaning reduced the dry matter (DM), crude protein (CP), and ether extract (EE) intake and digestion, but increased the starch, neutral detergent fiber (NDF), and acid detergent fiber (ADF) intake and digestion (p < 0.05). Weaning did not affect the overall jejunal microbiota (p > 0.05), but affected the relative abundance of certain bacteria taxa (p < 0.05). Lactic acid-producing bacteria, such as Olsenella, Bacillus, Sharpea, and Bifidobacterium are closely related to CP or EE digestion and growth performance (p < 0.05). In summary, we delineated the pattern of nutrient digestion and intestinal microbiota development in young lambs, and the impact of early weaning.