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.

探明断奶对羔羊消化功能变化的影响，可为制定羔羊早期生命阶段的高效干预策略提供理论依据。本研究将24只羔羊分为两组：对照组（未实施断奶处理的羔羊）与断奶组（于21日龄进行断奶的羔羊）。研究测定了7~49日龄羔羊的生长性能、营养物质消化率、胃肠道酶活性、血浆生化指标及肠道菌群组成，并分析了早期断奶的影响。营养物质消化率随日龄增长快速变化，尤其在14~28日龄阶段差异显著（p<0.05）。断奶会降低干物质（dry matter, DM）、粗蛋白（crude protein, CP）与乙醚浸出物（ether extract, EE）的采食与消化量，但会提升淀粉、中性洗涤纤维（neutral detergent fiber, NDF）与酸性洗涤纤维（acid detergent fiber, ADF）的采食与消化量（p<0.05）。断奶对空肠整体菌群结构无显著影响（p>0.05），但会改变部分细菌类群的相对丰度（p<0.05）。产乳酸细菌包括Olsenella属、芽孢杆菌属（Bacillus）、Sharpea属与双歧杆菌属（Bifidobacterium），与粗蛋白或乙醚浸出物的消化及生长性能密切相关（p<0.05）。综上，本研究阐明了幼年羔羊营养物质消化与肠道菌群发育的变化规律，以及早期断奶的影响。