Author : Simbulan, Maria Fe A.

Summary : Studies on the effects of the different levels of zinc oxide and zinc methionine were conducted in chickens. Studies 1, 2 and 3 dealt on broilers, layers and roosters, respectively. Results in broilers revealed that zinc oxide did not affect the production performances; growth and development of the bursa, thymus and spleen. In terms of meat zinc content, only the breast of broiler fed zinc oxide at 36 days showed the highest zinc level while other meat parts were not influenced even at 42 days of harvest. The same parameters were also not affected by zinc methionine except the thigh and legs at day 36 which revealed high zinc content. At days 42, all meats are comparable in zinc content regardless of treatment. In layers, zinc oxide did not influence the feed intake, egg weight, shell strength and fecal zinc content. Higher zinc content was note on the 4th-6th weeks in both experiments. Zinc methionine diet did not affect the layers' feed intake but egg weight was influenced at 3 and 8 weeks of feeding. Stronger shell was noted on the 6th week. Plasma zinc content is not reliable method of assessing the zinc status of roosters.