The effect of zinc-containing diets on performance, egg quality and internal organs of laying hens

The objective of this experiment was to investigation the effects of zinc-containing molting diets as alternative to the conventional feed withdrawal method, on performance,egg quality and the status of the internal organs of laying hens at 80 weeks of age. Experiment was carried out as a complete randomized design with 5 treatments, four replication and five samples in each replication. Treatments were include: molting diet+ 1% zinc oxide, molting diet+ 1.5 % zinc, molting diet+ 1% zinc acetate, molting diet+ 1.5 % zinc acetate, molting diet. Treatments were applied for 10 days to induce molting. Hens were weighted before and after molting, feed intake, egg production rate, egg production,egg quality, reproductive and non-eproductive organs weight and zinc accumulation in kidney and liver were measured. Data analyzed with ANOVA and the means were compared with Duncan multiple range test. Body weight loss and decline in feed intake were observed in all treatments. Egg production stopped after three weeks, in all treatments. After molting, egg production of birds on 1% ZnO egg production sooner than the other treatments. After molting, Egg shell breaking strength increased applying 1.5% zinc acetate. Ovary weight (as % of body weight) decreased using 1.5 % zinc acetate. Zinc bioaccumulation increased in liver and kidney applying zinc treatments. Force Molting with a diet containing 1% zinc oxide is recommended. Zinc-containing diets resulted to complete egg molting and improved egg shell quality. 1% zinc oxide resulted to faster return to egg production and less zinc bioaccumulation in the body.