Effect of increasing zinc concentration in the diets of brown parent stock layers on various production and hatchability traits

Effect of increasing zinc concentration in the diets of brown parent stock layers on various production and hatchability traits was investigated. After hatching, chicks were allocated to different treatment groups whose diets were formulated to contain graded concentrations 60 (control), 90, 120, 150, 180 and 210 mg zinc (Zn) kg(-1) throughout 62 weeks. No effect of increasing zinc concentration on egg production, 5% egg production age, livability and hatchability rate was found (P>0.05). On the other hand, significant differences were obtained with increase in zinc concentration in egg weight, feed conversion rate and hatchability effciency of the fertile eggs (P<0.05). The results of the present study suggest that the diets of brown parent stock layers should include 180 mg Zn kg(-1) for optimal performance and hatchability traits.