Weaning weight–related differences in growth performance, nutrient digestibility, blood profiles, and intestinal morphology in pigs

This study was conducted to evaluate whether weaning weight (WW) at 28 d of age could serve as an indicator of postweaning robustness by comparing growth performance, nutrient digestibility, blood profiles, and intestinal morphology of pigs differing in body weight (BW). Among a total of 124 pigs, 74 pigs corresponding to the upper and lower 30% of the WW distribution were selected and assigned to heavy BW (HBW) and light BW (LBW) groups, respectively, and monitored until d 56 of age. In this study, the HBW group showed higher (<italic>p</italic> < 0.05) body weight, average daily gain, and apparent total tract digestibility of dry matter, crude protein, and gross energy than the LBW group. Differences in intestinal morphology were observed, HBW group exhibiting higher (<italic>p</italic> < 0.05) villus height (VH), villus width (VW) and villus height to crypt depth ratio (VH:CD). Blood profiles indicated elevated (<italic>p</italic> < 0.05) cortisol, tumor necrosis factor-α, interleukin-6, and interleukin-10 levels in LBW group, reflecting enhanced systemic stress and inflammatory activation. Correlation analysis further demonstrated positive associations between WW and growth performance and nutrient digestibility, VH, VW and VH:CD while showing negative correlations with inflammatory and stress markers. These results indicate that WW is closely linked to postweaning physiological responses and serve as a practical predictor of robustness, digestive capacity, and growth potential during the nursery phase.