Influence of complexed zinc products on live performance and carcass gradeof broilers

The influence of supplementing diets with zinc (Zn) amino acid complexes on live performance and carcass quality of female (Experimental 1) and male b roiler chickens (Experiment 2) was investigated. In Experiment 1, day-old f emale chicks were fed, under summer conditions, one of 4 dietary treatments : a control and diets supplemented with Zn (40 ppm) from Zn-methionine, Zn- lysine, or a commercial mixture of Zn-methionine and Zn-lysine. During the rearing periods, body weight and feed conversion were measured. Randomly se lected birds were processed with subsequent evaluation of foot pad lesions and carcass grades. In Experiment 2, male chicks were fed similar diets as Experiment 1, but under cool weather conditions. Live performance variables were measured and randomly selected birds were processes to assess carcass defects, carcass grade, foot pad lesions and carcass yields. In Experiment 1, feed conversion and foot pad lesions were reduced (P<0.05) in female br oilers fed the Zn-amino acid complexes, with no consistent alterations in c arcass grade other than improvements in wing and back bruising. Body weight of male broilers was improved at 21d with Zn-methionine and Zn-lysine supp lemented diets, with improvements in back bruising. no differences in foot pad quality ir carcass yields of male broilers was observed among the dieta ry treatments (P>0.05). The influence of zinc complexes on broiler live per formance, carcass bruising and foot pad quality appeared to vary with envir onmental conditions.