Supplementation of graded levels of organic zinc in the diets of female broilers: effects on performance and carcase quality

1. Zinc is an essential trace element. The objective of this research was to investigate the effects of various levels of organic zinc (OZ) supplementation on growth performance and carcase quality of female broiler chickens. 2. A total of 3200 1-d-old female broiler chicks were randomly allotted to 16 floor pens with 200 birds per pen. A maize-wheat-soyabean meal basal diet (Control) was formulated and 20 mg/kg OZ (20 OZ), 40 mg/kg OZ (40 OZ), and 80 mg/kg OZ (80 OZ) were added to the basal diet to form 4 dietary treatments with 4 replicates per treatment. The OZ source was zinc proteinate which contained 15% zinc. 3. Results showed no significant difference between the treatments in growth performance. A significant increase in thigh skin epidermis and dermis thickness was shown in the OZ supplementation groups; however, no effect was found on the thickness of back skin epidermis and dermis. 4. Collagen contents in breast and thigh meats were not influenced by OZ supplementation but a significant increase in collagen content was found in the back and thigh skin. This increase in collagen content was significantly greater in the back and thigh skin of OZ 80 than with OZ 20. 5. Shear force value and zinc concentration in skins and meat were not significantly influenced by supplementation with OZ. 6. It is concluded that dietary OZ does not improve growth performance of broilers; however, it could increase skin thickness by increasing collagen content in skin, thereby improving carcase quality.