Revista Brasileira de Zootecnia
On-line version ISSN 1806-9290
BARBOSA, Breno Augusto Campolina et al. Nutritional requirements of methionine+cystine by white-egg and brown-egg layer hens in the second production cycle: 1. productive traits. R. Bras. Zootec. [online]. 1999, vol.28, n.3, pp.526-533. ISSN 1806-9290. http://dx.doi.org/10.1590/S1516-35981999000300013.
An experiment was conducted to establish the nutritional requirements of methionine+cystine (Met+Cys) for white-egg and the brown-egg layers hens in the second production cycle. Two hundred and twenty eight Lohmann Selected Leghorn and 288 Lohmann Brown laying hens were submitted to forced molting at the 76 weeks of age, were used. A completely experimental randomized experimental design was used. The treatments consisted of two egg laying strains and six Meth+Cys levels, with six replicates and eight birds per experimental unit. The birds were fed a basal diet with 2,751 kcal ME/kg, 14.20% CP, and .484% methionine+cystine, supplemented with six levels of DL-methionine (0, .05, .10, .15, .20, and .25%). Egg production (%), egg mass (g/bird•day), egg weight, feed intake (g/bird•day) and feed:gain ratio were evaluated. The white-egg layer hens presented better production index, egg mass and feed:gain ratio, and the brown-egg layer hens, better egg weight and feed intake. The increasing levels of Meth+Cys influenced the production characteristics, egg mass, average egg weight, feed intake and feed:gain ratio. The methionine+cystine requirements, estimated by quadratic model, were .692 and .655% for white-egg and brown-egg layer hens, respectively, which correspond to a daily intake per hen of .785 and .779g of Meth+Cys, respectively. These results correspond to .649 and .612% of digestible met+cys for the white-egg and the brown-egg layer hens, respectively.
Keywords : nutritional requirement; methionine+cystine; white-egg and brown-egg layer hens; second production cycle.