This study was conducted in the Poultry Section of the Animal Science Department at the Federal University of Santa Maria, RS - Brazil, from September 12th to November 1st, 1989. The main objective was to evaluate the effect of two different sources and levels of synthetic methionine on the broiler performance, raised separetely by sex, from day old up to 49 days of age. A total of 640 dayold chicks, from both sexes, on pen floor were used. The experimental design was enterely randomized in a factorial 2 x 2 x 2 (source x level x sex) with 4 replicates of 20 chicks each. The sources of methionine were DL-Methionine and Methionine Hidroxy-analogue, and the levels were 1.500 and 1.050ppm for phase I (1 - 20 days); for phase II (20 - 42 days) and phase III (42 - 49 days), were 83.33 and 75.0% of the phase I, respectively. Diets contained 20.5, 19.5 and 17.5% of crude protein and 3.000, 3.050 and 3.100kcal/kg of ME for phase I, II and III, respectively. In all phases, males were significantly better than females for all parameters studied. Weight gain was different at phases I and III for sources and levels, but not in the overall period which demonstrates a compensatory growth through the period. Feed consumption and feed conversion for the overall period (1 - 49 days) did not show significant differences for sources or levels. Viability was similar between sexes and also related to sources or levels of methionine suplementation. The productive efficiency index (IEP) was 21.4% better for males than females. Feathering score was significantly better for females. The abdominal fat and carcass yield were not affected by sources or levels of methionine, but highly differents between sexes; females had 26.2% more abdominal fat deposition than males, and the carcass yield was 2.7% better for males. It was concluded that both sources of methionine (DL-Methionine or MHA) on a equimolar basis of adition for broiler diets, can be used without any reduction of performance.
aminoacids; DL-Methionine; MHA - FA
