Use of 25-hydroxycholecalciferol in Diets of Broiler Chickens: Effects on Growth Performance, Immunity and Bone Calcification

Abstract

An experiment was conducted in mixed sexes broiler chickens 1-d-old (Ross 308) to investigate the effects of 25-hydroxycholecalciferol (25-OH-D₃) on growth performance parameters, immunity and bone calcification. A completely randomized design with 4 experimental diets was used: 1) diet with cholecalciferol (VIT-D3) at 200 IU/kg of feed (NRC-1994 level); 2) diet with 25-OH-D₃ at 69 μg/kg of feed; 3) diet with VIT-D3 at 2000 IU/kg of feed (commercial level); and 4) as diet 3+25-OH-D₃ at 69 μg/kg of feed. Experimental treatments consisted in 6 repetitions of 10 chickens each. On 21 d of trial, chickens fed diets with VIT-D3 at commercial level (with or without 25-OH-D₃) increased the BWG (P<0.05) than those supplemented with VIT-D3 at NRC-1994 level or single 25-OH-D₃. The feed conversion ratio of chickens was improved (P<0.01) by using diets supplemented with VIT-D3 at commercial level (with or without 25-OH-D₃) than that diet with VIT-D3 at NRC-1994 level. Calcium content in tibias of broiler (21 d old) was increased (P<0.05) with the use of diets added 25-OH-D₃＋VIT-D3 (commercial level) respect to those diets with VIT-D3 at NRC-1994 or commercial level. At 14 d, chickens fed diets with 25-OH-D₃ increased (P<0.05) the delayed cutaneous hypersensitivity response than those fed only VIT-D3 (NRC-1994 or commercial levels). The antibody response against Newcastle disease vaccine was better (P<0.05) in chickens fed diets with commercial levels of VIT-D3 (with or without 25-OH-D₃) than those diets, VIT-D3 NRC-1994 level or single 25-OH-D₃ supplementation. It can be concluded that higher levels of VIT-D3 (2000 IU/kg of feed) than those recommended by NRC (1994) improved the growth performance and the antibody response; and the supplementation of 25-OH-D₃ at 69 μg/kg of feed increased the cellular immune response and the bone calcification of broiler chickens.