The Effects of Partially or Completely Substituted Dietary Zinc Sulfate by Lower Levels of Zinc Methionine on Growth Performance, Apparent Total Tract Digestibility, Immune Function, and Visceral Indices in Weaned Piglets

摘要

The study aimed to evaluate the effects of replacing zinc sulfate (ZnSO4) with a lower level of zinc methionine (ZnMet) on the growth performance, apparent total tract digestibility (ATTD) of nutrients, serum metabolites and immune functions of weaned piglets. Thirty-five weaned Duroc × Landrace × Large White male piglets (10.69 ± 0.26 kg) were randomly allotted to five diets. The control diet was supplemented with 100 mg/kg of Zn from ZnSO4, and experimental diets included 75 + 12.5, 50 + 25, 25 + 37.5, and 0 + 50 mg/kg of Zn from ZnSO4 and ZnMet, respectively. The results showed that no differences were observed in growth performance, ATTD of nutrients and serum metabolites among treatments, while serum white blood cell count, lymphocyte count, IgM contents and spleen index were higher (p < 0.01) in piglets fed with 50 + 25 mg/kg of Zn. Zinc digestibility (p < 0.05), IgA content (p < 0.001) and thymus index (p < 0.05) were increased when at least 50% of ZnSO4 was replaced by ZnMet. All the results indicated that using a lower level of ZnMet in weaned piglet’s diet instead of ZnSO4 had no adverse impacts on ATTD of nutrients and serum metabolites; and a 50 + 25 mg/kg of Zn (from ZnSO4 and ZnMet, respectively) diet showed the best advantages for parameters relating to immune functions.