Effects of Pig Weaning Weight and Sex on Growth Performance, Fecal Score, and Blood Antioxidant Capacity in Early Nursery Period

This experiment aimed to determine the effects of weaning weight (WW) and sex on growth performance, fecal score, gut permeability, and antioxidant status in pigs. At weaning (19.0 ± 1.35 d of age), 64 newly weaned pigs (32 barrows and 32 gilts) were allotted to two WW categories: high-WW pigs (>5.5 kg) and low-WW pigs (<5.5 kg) in eight replicates (four pens for barrows and four pens for gilts) for a 28 d feeding trial. High-WW pigs showed greater body weight (p < 0.01) than low-WW pigs every week. During the overall period, high-WW pigs showed greater weight gain (p < 0.01) and feed intake (tendency p = 0.06) than low-WW pigs. Weaning weight was positively correlated with overall weight gain (r = 0.853), feed intake (r = 0.714), and feed efficiency (r = 0.719) in gilts but there was no or negative correlation in barrows. Weaning weight showed a tendency for a negative correlation with fecal score during d 7–14 (r = −0.500; p < 0.10). Serum D-lactate levels on d 0 post-weaning were positively correlated (r = 0.826; p = 0.01) with WW in barrows but not in gilts. The level of serum malondialdehyde in high-WW pigs on d 7 tended to be less (p = 0.07) than that in low-WW pigs. Fecal acetate, propionate, butyrate, and total short-chain fatty acid concentrations were not affected by WW at d 0, 14, and 28 post-weaningg. Weaning weight was positively associated with the overall growth performance of nursery pigs with more pronounced effect in gilts while no interactions between WW and sex were observed in gut permeability, antioxidant status, and fecal short-chain fatty acid concentrations, implying that sex-specific nutritional strategies and precision weaning management are warranted.