Comparison of the effects of feeding diets supplemented with zinc oxide or zinc acetate on the performance and tissue mineral content of mature female fowls.

An experiment is reported in which zinc, as acetate or oxide, was fed to laying hens for 10 weeks at concentrations equivalent to 1, 2, 3, 4 and 5 g added Zn/kg diet. Both concentration and form of Zn additive significantly reduced food, water and Zn intakes, egg production and body weight, the acetate having a greater detrimental effect than the oxide at equivalent added Zn inclusion. Zinc acetate depressed the fresh weight/kg body weight of the kidneys, ovary and oviduct to a greater extent than the corresponding oxide treatments. Concentration, but not form of additive, significantly reduced liver and pancreas weights and liver lipid concentration, while spleen and gizzard weights showed increases. Overall, the additives significantly increased the Zn and Fe concentrations of the liver, kidneys, pancreas and gizzard. Zinc concentrations of liver, pancreas and gizzard and Fe concentrations of liver were consistently higher for the acetate-fed birds. Liver, pancreas and gizzard Cu concentrations significantly declined as inclusion rate of Zn increased.