ALTINER A, BILAL T, ESECELI H, ESEN GURSEL F. Effect of vitamin D3 and/or zeolite supplementation to laying hen rations added microbial phytase on some blood indices. 2. Total cholesterol, 1,25-dihydroxycholecalciferol and oestradiol-17 levels. Kafkas Univ Vet Fak Derg, 16 (3): 419-424, 2010. DOI: 10.9775/kvfd.2009.855