This study was conducted to investigate the effect of pigs’ weaning weight (WW) on their growth performance and blood immunological, antioxidant, and gut permeability parameters in the early nursery period. At weaning, a total of 48 pigs, weaned at 20.7 ± 0.74 d of age, were allotted to two WW categories—HWW, with a WW over 5.5 kg (average 6.79 ± 0.53 kg), and LWW, with a WW of less than 5.5 kg (average 4.43 ± 0.56 kg)—for a 14 d postweaning period. The WW did not affect the average daily gain (ADG) in d 0–7 postweaning or the plasma malondialdehyde levels over the entire period. HWW pigs had a higher body weight and ADG than LWW pigs (p < 0.05) in the overall period, with greater plasma immunoglobulin G (p < 0.05) and A (p = 0.06, tendency) levels at d 7 postweaning and superoxide dismutase activity at d 14 postweaning (p = 0.05, tendency), with positive correlations with the WW (p < 0.05). HWW pigs had lower plasma diamine oxidase (p < 0.05) and d-lactate (p = 0.06, tendency) levels at d 14 postweaning, with a negative correlation with the WW (p < 0.05). In conclusion, although there was no effect of the WW on growth rate in the first week postweaning and oxidative stress in the early nursery period, HWW pigs exhibited greater growth performance, immunoglobulin levels, and antioxidant capacity but lower gut permeability than LWW pigs in the early nursery period.

This study evaluated the effects of dietary 25-hydroxycholecalciferol alone or in combination with vitamin D₃ (VD₃) on growth performance, vitamin D status, immune parameters, bone integrity, and antioxidant capacity in nursery pigs. Sixty weanling piglets (5.63 ± 0.98 kg initial body weight) were assigned to three treatments for a 28 d feeding trial. The treatments were a basal diet supplemented with 2000 IU/kg VD₃, a combination of 1000 IU/kg VD₃ and 1000 IU/kg 25-hydroxycholecalciferol (25-OHD₃), and 2000 IU/kg 25-OHD₃. Pigs fed diets containing 25-OHD₃ tended to have greater feed intake during d 14–28 (p = 0.06). Plasma 25-OHD₃ concentrations were greater in pigs fed diets containing 25-OHD₃ than in those fed VD₃ alone on d 14 and 28 (p < 0.05), with greater values observed in pigs fed 2000 IU/kg 25-OHD₃ than in those fed a combination of 1000 IU/kg VD₃ and 1000 IU/kg 25-OHD₃ on d 14 (p < 0.05). Pigs fed diets supplemented with 25-OHD₃ had lower plasma malondialdehyde concentrations at d 28 (p < 0.05), while immune parameters and bone mineralization indicators were unaffected. In the broken-line analysis, the estimated plasma 25-OHD₃ concentration for plasma malondialdehyde concentrations to reach the minimum level was 32.5 ng/mL (p < 0.05). In conclusion, supplementing 25-OHD₃ in nursery diets improved blood vitamin D status and could help reduce oxidative stress during the late 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.