Effect of supplementing lactation and nursery pig diets with capsaicin on growth performance and gene expression of nursery pigs

The objective of this study was to determine the effects of supplementing capsaicin in diets for lactating sows and their offspring on the growth performance and gene expression of pigs postweaning. Twenty-eight multiparous sows were fed corn-soybean meal-based diets without (n = 14) and with (n = 14) capsaicin (2.5 mg/kg) during a 19-d lactation period. Litters from these sows (n = 288 pigs) were weaned and assigned to 36 blocks (pens) based on maternal dietary treatment and initial body weight (BW) to provide 8 pigs/pen. Blocks were assigned randomly to one of two nursery dietary treatments (control or capsaicin supplemented diets) in a 2 × 2 factorial arrangement of treatments to provide nine replications per treatment combination. A three-phase nursery feeding program was used and consisted of feeding phase 1 (weaning to d 7), phase 2 (d 8–21), and phase 3 (d 22–38) diets postweaning, without and with 1.0, 1.3, and 1.6 mg capsaicin/kg of diet, respectively. Data were analyzed using a mixed model with the effect of nursery dietary treatment nested within sow lactation treatment, the effect of time with repeated measures, and interactions between treatments and wk postweaning. On d 38 postweaning, blood samples were collected from one pig in each pen (n = 36) with BW closest to the pen average for RNA sequencing and gene expression analysis. There were no effects of feeding capsaicin diets to lactating sows and/or their weaned offspring on BW, average daily gain, or average daily feed intake of pigs during the 35-d nursery period. However, pigs weaned from sows fed capsaicin during lactation and continuing to be fed capsaicin diets during the nursery period tended (P = 0.09) to have greater gain:feed (G:F) than pigs fed the other dietary treatments. Furthermore, there was an interaction (P < 0.01) for G:F for dietary treatment and week postweaning, where the magnitude of improvement was greater during the first week postweaning than subsequent wks. There were a limited number of differentially expressed genes among dietary treatment combinations but the greatest number occurred in offspring from sows that were fed capsaicin during lactation. In conclusion, the combination of feeding capsaicin to sows during lactation and to their offspring after weaning appears to improve gain efficiency for the first wk postweaning and may alter gene expression to a greater extent than when capsaicin is supplemented only in the nursery diets.