EL-HUSSEINY, O.M.; ABD-ELSAMEE, M.O.; OMARA, I.I.; FOUAD, A.M. Effect of Dietary Zinc and Niacin on Laying Hens Performance and Egg Quality. International Journal of Poultry Science, Pakistan, v. 7, n. 8, p. 757–764, 2008. DOI: 10.3923/ijps.2008.757.764. Disponível em: https://ijpsjournal.org/index.php/ijps/article/view/1028. Acesso em: 21 sep. 2025.