Zinc Oxide as an Effective Mineral for Induced Moulting: Effects on Post Moult Performance of Laying Hens in the Humid Tropics

The aim of this study was to evaluate the ability of using zinc oxide salts to induce moulting, and their effects on post moult performance and organ characteristics of laying hens.Two hundred (75 weeks of age) Isa Brown hens were randomly assigned to five Treatments (T) groups of 40 hens, each namely; T 0 -non-moulted hens and T 1 , T 2 , T 3, T 4 , representing moulted hens fed, respectively, 0.5%, 1.0%, 1.5% and 2.0% Zinc Oxide (ZnO) supplementation per kg diet for 14 days.Organ evaluations of the hens were carried out 7 days post moult.Body weight loss and decline in feed intake of the birds were higher (P<0.01)for moulted hens.Cessation of egg production occurred earlier (P<0.05) in the same groups of birds.During post moult, the moulted hens exhibited greater (P<0.01)percentage body weight gain, when compared with the non-moulted hens.Feed intake and hen-day egg production of birds on 1.0%, 1.5% and 2.0% ZnO supplementation was higher (P<0.01),than those of other treatments.Feed conversion ratio was better (P<0.05) for the same groups of birds.Moulting with ZnO treatment influence highly (P<0.01) the number of days to resumption of egg production, with hens on 2.0% ZnO resuming egg production much later than hens on 0.5%, 1.0%, and 1.5% ZnO treatments.The ovary, liver and kidney of the hens were affected (P<0.05) by the dietary ZnO contents.A greenish coloration of the liver was observed in hens fed 1.5% and 2% ZnO supplementation.These results demonstrate that in order to achieve good post moult performance of laying hens in the humid tropics, farmers should practice the use of 1% ZnO inclusion per kg diet, as an effective method to achieve induced moulting.