Dietary Effects of Free Insulin-like Growth Factor-1 Supplementation on the Production Performance, Serum Tumor Necrosis Factor-α, and Nutrient Digestibility in 50–80-day-old Pigs

This study analyzed the impact of nutritional supplementation of insulin-like growth factor-1 on the production performance, nutrient digestibility, complete blood count (CBC), and serum content of tumor necrosis factor-α (TNF-α) on 50 pigs (Large White x Landrace) aged 50–80 d assigned randomly to five treatments, including one basal and four treatment diets with IGF-1 supplementation. Feeding lasted for 28 d, after which five pigs from each treatment underwent a nutrient digestibility test. Blood samples were extracted from the external jugular vein on Days 14 and 28 for TNF-α analysis and on Days 15 and 30 for CBC. Results showed no significant variations among treatments for body weight, feed intake, average daily gain, and feed conversion ratio, as well as in crude protein and fat, and digestible and metabolizable energy. However, the average fecal score for Days 1–28, Treatment C differed significantly being the poorest. On Day 14, pigs fed with treatment diets from 0.25–2 kg/ton tended to have lower TNF-α serum concentrations. On Day 15, WBC count was reduced starting at 0.5 kg/ton supplementation, whereas RBC count was higher in pigs fed with treatment diets from 0.25–2 kg/ton. Concluding, the dietary supplementation of IGF-1 does not significantly affect production performance and nutrient digestibility.