Effect of Weaning Age on Plasma Biochemistry and Muscular GHR, IGF-1 and IGF-1R Gene Expression in Piglets

摘要

The effects of weaning age on plasma biochemistry parameters and expression of growth-related genes in piglets were investigated. Twenty-four piglets were randomly divided into 4 weaning groups (14 d, 21 d, 28 d and 35 d) and slaughtered at the age of 42 days. Blood, longissimus dorsi muscle (LD), and semitendinosus tissue samples were collected. Plasma biochemistry parameters and GHR, IGF-1, and IGF-1R mRNA and protein were measured. Weaning piglets at 14 days resulted in significantly lower plasma TP and GLU compared to weaning at 28 and 35 days (p < 0.05). Weaning at 28 and 35 days resulted in lower plasma CK activity compared to weaning at 14 and 21 days (p < 0.05). Weaning piglets at 35 days resulted in lower plasma LDH activity compared to weaning at 14 days (p < 0.05). Weaning at 21 days after birth resulted in significantly higher expression of GHR mRNA and protein in LD and semitendinosus muscles compared to weaning at 14 days (p < 0.05). IGF-1 protein in LD and IGF-1 mRNA in LD and semitendinosus muscles were significantly elevated in the 21 days weaning group compared to weaning at 14 days (p < 0.05). Weaning at 21 days resulted in significantly elevated mRNA and protein levels for IGF-1R in LD and semitendinosus muscles compared to weaning on any other day (p < 0.05).