Breeding-hen and progeny performance when hens are fed excessive dietary zinc

Short-term (12 wk) and long-term (44 wk) studies were conducted to observe the effects of excessive Zn supplementation on the performance of breeding hens and their progeny. Zinc sulfate was added to a corn-soybean meal diet containing 28 mg of Zn/kg in order to provide Zn supplementation at 0, 20, 200, and 2,000 mg/kg. Each dietary treatment was fed to two groups of 20, Single Comb White Leghorn hens and one New Hampshire rooster. The hens were 56-wk old at the start of the short-term study and 24-wk old when the long-term study began. Determinations were made for: fertility, hatchability, progeny growth to 3 wk of age, Zn-related feather-fraying among the progeny as well as Zn, Cu, and Fe in the liver, pancreas, and right tibiotarsus. The Zn treatments had no effect on hen performance or on reproductive performance. Even though Zn was considerably elevated and Cu was reduced in the eggs collected from hens fed the highest level of Zn, chick performance and the tissue content of Zn, Cu, and Fe were not influenced by the maternal Zn nutritional status.