Supplementation of diets to nelore calves at weaning with organic and inorganic zinc sources

Abstract

The objective of this study was to evaluate the effect of different zinc sources in the diet of Nellore calves in relation to immune and physiological response. Sixty weaned calves, with 220kg body weight were submitted to four treatments: A- without zinc supplementation; B- 30mg of zinc as zinc sulfate/kg of dry matter; C- 30mg of zinc as amino acid zinc/kg of dry matter; D- 30mg of zinc as proteinate zinc/kg of dry matter. Every 28 days, the animals were weighted and sampled for blood zinc analysis, phosphatase alkaline and immunoglobulins G and M. The calves were kept in Brachiaria brizantha pastures with ad libitum access to a mineral mixture. Zinc was analyzed by atomic absorption spectrophotometer while phosphatase alkaline and immunoglobulins G and M were analyzed using the LabTest kit. Regarding the levels of immunoglobulin M, the amino acid zinc and proteinate zinc treatment do did not differ but were superior than control and zinc sulfate treatment. In relation to zinc levels, amino acid zinc treatment was only superior to zinc sulphate. There was no difference on phosphatase alkaline, immunoglobulin G and body weight among treatments indicating that there was no advantage of using organic sources over the inorganic.