DIETARY ARGININE AND LYSINE IN LARGE WHITE TOMS - 1 - INCREASING ARGININE - LYSINE RATIOS DOES NOT IMPROVE PERFORMANCE WHEN LYSINE LEVELS ARE ADEQUATE

A study was conducted utilizing two strains of male Large White turkey s (BUT Big 6 and Nicholas 700) to determine the effects of increasing Arg: Lys ratios on live performance and carcass composition. Diets wer e formulated to provide 100, 110, and 120% of NRC (1994) Lys levels, a djusted for dietary energy level, with Arg:Lys ratios of 1.0:1, 1.1:1, 1.2:1, and 1.3:1 in a 3 x 4 factorial arrangement. Eight pens of 15 p oults (four pens of each strain) were fed each of the 12 test diets fo r an 18-wk period. Diets were changed at 3-wk intervals rather than th e 4-wk interval suggested by NRC. The results of this study suggest th at the Arg and Lys levels suggested by the NRC (1994) are not sufficie nt when diets are fed on 3-wk intervals, rather than the 4-wk interval s suggested by NRC. This conclusion is in agreement with the studies o f Waldroup et al. (1997b). Increasing Arg:Lys ratios improved performa nce of turkeys only when the diets contained insufficient amounts of A rg in association with low levels of Lys. Increasing Arg:Lys ratios wh en diets contained sufficient amounts of these two amino acids was wit hout benefit, in contrast to the report of Brake et nl. (1994). Turkey s of the BUT Big 6 strain appeared to be more sensitive to marginal de ficiencies of Lys and Arg than did turkeys of Nicholas 700 strain.