Insight into the long-term impact of birth weight on intestinal development, microbial settlement, and the metabolism of weaned piglets

The drawback of the high prolificacy selection in the swine industry in the past decades is an increase in the number of piglets born with a low birth body weight (LBBW). This study aimed to assess performance, metabolism, gut status, and microbial profile in piglets born with low (0.92 ± 0.07 g) and normal birth body weight (1.38 ± 0.09 g). Piglets were weighed weekly from weaning (25 d) until 3 weeks postweaning (end of the trial). At d9 and d21, 8 piglets/group were slaughtered to obtain blood for metabolomic, haptoglobin, reactive oxygen metabolite analyses, colon content for microbiota and short-chain fatty acid, intestinal content for pH measurement, distal jejunum for morphology, immunohistochemistry, and gene expression. The LBBW resulted in lower body weight through the study (P < 0.001), lower average daily gain from d9 to d21 (P = 0.002), and lower feed intake (P = 0.02). The LBBW piglets had a lower villus height, absorptive mucosal surface (P = 0.01), and villus height:crypt depth ratio (P = 0.02), and a greater number of T-lymphocytes in both the epithelium and the crypts (P < 0.001) at d21. In conclusion, the present study confirmed that LBBW could impact the gut mucosal structure, immunity, and inflammatory and oxidative status, leading to an altered AA metabolism, and delaying the recovery from weaning.