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Revista Brasileira de Zootecnia
On-line version ISSN 1806-9290
SILVA, Edson Lindolfo da et al. Methionine+cystine requirements for light and semi-heavy replacement birds fed mashed or pelleted feeds. R. Bras. Zootec. [online]. 2009, vol.38, n.12, pp.2425-2434. ISSN 1806-9290. http://dx.doi.org/10.1590/S1516-35982009001200019.
The objective of this study was to reevaluate the requirements of Methionine+cystine (met+cis total) of light (L) and semi-heavy (SH) pullets at 5 to 11 weeks of age considering the physical shape of the feeds and the performance in the 22 to 40 week period, the laying phase. A total of 1,120 laying pullets (560 lightweight and 560 semiheavy) in a randomized completedesign in a 5 ×2 ×2 factorial scheme with 20 combinations consisting of five total Met+Cys levels (0.56; 0.60; 0.64; 0.68 or 0.72), two physical shapes (mashed and pelleted) of the feed and two lines (Dekalb White and Bovans Goldline) each with four replications of 14 birds each. The basal rations were supplemented with DL-Met. (99%) to provide five total Met+Cys levels according to the recommendations of the Brazilian literature and the line handbook. The experimental feeds of the growing period were isonutritive in ME (2,900 kcal/kg), CP (17%), Ca (1,000) and available P (0.450), containing total Met+Cy levels of 0.56; 0.60; 0.64; 0.68 and 0.72, while in the laying period, a single diet with 2,850 kcal/kg ME, (16%) CP, (3.70%) of Ca and (0.340%) of available P was fed. The semiheavy birds performed better compared to the light birds. The pelleted feed provided better total and daily feed intakes compared to the mashed feed. In the laying phase, the Met+Cys levels affected production, egg weight and mass and conversion to egg mass. The levels of Met+Cys and the physical shape of the feed over the laying period affected the subsequent performance of the birds in the laying period. The light line performed best. Levels of 320 and 364 mg Met+Cys daily are recommended for light and semi-heavy birds, respectively.
Keywords : amino acid; commercial laying hens; physical shape; rearing period.