Effects of different selenium sources on production performance, thyroid level and immune function in sows during lactation

Objective This experiment was conducted to study the effects of different Se sources on production performance, thyroid level and immune function in sows during lactation.

Method A total of 200 LY (Landrace×Yorkshire) binary hybrid multiparous sows (healthy, with similar body condition, close due date, 3-6 parities) were allotted to 10 groups randomly, with 20 replications in each group. Group one was the control group fed with basal diet without supplementation of Se. The other 9 groups were supplemented with 0.3, 0.5 or 0.7 mg ·kg^-1 Se-containing sodium selenite, yeast selenium or nano-selenium respectively. The whole feeding experiment lasted for 58 days.

Result and conclusion The birth mass of group supplemented with yeast selenium by 0.3, 0.5 mg ·kg^-1 or nano-selenium by 0.5, 0.7 mg ·kg^-1 was significantly higher than that of the control group (P < 0.05). The group with 0.5 mg ·kg^-1 selenium yeast was significantly higher than those of the control group and the group with sodium selenite in mass of weaning litter, litter mass gain and daily gain(P < 0.05). The effect of different sources of selenium on 3, 3′, 5-triiodothyronine(T₃) and 3, 5, 3′, 5′-thyroxine(T₄) mass concentrations in serum of lactation sows and sucking piglets was extremely significant (P < 0.01). Compared with the control group, groups with sodium selenite or selenium yeast, the serum T₃ mass concentration of sows fed on the diets supplemented with nano-selenium group significantly(P < 0.01) increased by 29.52%, 17.24% or 23.63%, respectively, but the serum T₄ mass concentration significantly(P < 0.01) decreased by 24.71%, 30.88% or 33.86% respectively. Compared with the group with sodium selenite or selenium yeast, the serum IgA and IgM mass concentration of sows fed on the diets with nano-selenium increased by 85.39% and 79.35% (P < 0.01)or 24.19% and 50.98% (P < 0.01) respectively. Compared with the control group, the serum IgG mass concentration of sucking piglets from the sows fed on the diets with sodium selenite, nano-selenium or selenium yeast significantly (P < 0.01) increased by 19.11%, 43.39% or 34.63% respectively, while the serum IgA and IgM mass concentration increased by 93.67%, 160.75% or 132.91% and 90.91%, 140.91%or 102.27% respectively. The results indicate that nano-selenium or selenium yeast supplemented in diets can significantly improve the reproductive performance and immune function of sows, and regulating the secretion of thyroxine.