Dietary arginine and lysine ratios in Large White toms. 2. Lack of interaction between arginine:lysine ratios and electrolyte balance.

The effect of dietary Arg:Lys ratios and dietary electrolyte balance (DEB) on growth and carcass parameters of Large White toms was evaluated in one experiment from 8 to 20 wk of age. Growth, feed conversion, and carcass composition were measured. All toms received a common basal diet from 0 to 8 wk of age. At 8 wk of age, 600 toms were randomly placed into 40 pens (15 toms per pen). The corn-soybean meal-based experimental diets were fed from 8 to 12, 12 to 16, and 16 to 20 wk of age and evaluated two Arg:Lys ratios (0.98 vs 1.22) and two DEB levels (148 vs 202 mEq/kg of diet) in a complete factorial arrangement. All experimental diets were pelleted. Composite samples of protein-contributing ingredients and complete experimental diets were analyzed for all amino acids, CP, DM, Cl, Na, and K. High and low average house temperature for the 8 to 20 wk period were 19 and 15 C, respectively. No interactions occurred between Arg:Lys ratios and DEB for any parameter measured except litter moisture. Increasing the Arg:Lys ratio improved 20-wk BW (P < or = 0.027) and 8 to 20 wk gain (P < or = 0.023). Feed:gain from 0 to 20 wk of age was decreased by increasing the Arg:Lys ratio (3.01 vs 2.94; P < or = 0.026) and by increasing the DEB (3.01 vs 2.95; P < or = 0.045). Dietary treatments did not affect mortality. Increasing DEB decreased cold carcass yield (P < or = 0.020). Total breast meat yield was increased (P < or = 0.076) by 1% in toms fed the diets containing the 1.22 Arg:Lys ratio vs toms fed diets containing the 0.98 Arg:Lys ratio. Toms responded favorably to increasing the Arg:Lys ratio for growth, feed conversion, and breast meat yield independent of DEB level.