Levels of substitution of inorganic mineral to amino acids complexed minerals on old laying hens.

This study was conducted with the objective of evaluating the impact of replacing inorganic mineral sources (IM) with amino acid complexed minerals (AACM) in laying hens' diets on performance, egg quality, bone, and intestinal health. The effects of 4 different diets with varying levels of AACM substitution were evaluated on 400 Lohmann White hens aged 78-98 weeks. The control diet contained only IM sources at levels of 60, 60, 7, 40, 0.2, and 2 mg/kg of Zn, Mn, Cu, Fe, Se, and I, respectively. The other treatments were made by a total substitution of IM with AACM, as follows: AACM70-70% of IM levels; AACM50-50% of IM levels; and AACM40-40% of IM levels. Orthogonal polynomial contrasts and Dunnett's test were used to determine their impact (P < 0.05). The treatment AACM40 improved egg production, egg weight, egg mass, and feed conversion ratio (P < 0.05). Hens that received AACM40 also produced the thickest eggshells and better tibial bone density (P < 0.01). Histomorphometry analyses demonstrated significant effects of AACM treatments. The optimal supplementation levels of 24, 24, 2.8, 16, 0.08, and 0.8 mg/kg of Zn, Mn, Cu, Fe, Se, and I, respectively.