Influence of temperature on the arginine and methionine requirements of young broiler chicks

Two experiments were conducted with Ross x Ross broiler chicks in battery brooders from 7 to 21 d of age to determine the Arg and Met requirements of young broiler chicks at control (25 degrees C and warm (35 degrees C temperatures. In both experiments, 1-d-old broiler chicks were fed a corn and soybean meal based starter diet for 7 d. Six replications (2 replicates in each of 3 rooms per temperature) with 8 chicks each were used for each treatment. In experiment 1. the basal diet was based on corn (34.52%), whey (26.96%), corn gluten meal (16.53%), soybean meal (11.74%). and poultry fat (23% of CP and 3.20 kcal/g of ME,,). Six levels of Arg (0, 0.1, 0.2, 0.3, 0.4, and 0.5%), supplementing the basal diet containing 0.95% Arg, were the dietary treatments. A broken-line linear model was used to estimate chick Arg requirements. Based on body gain and feed conversion ratio (FCR) data, respectively, the Arg requirements of young Ross x Ross broiler chicks raised at 35 degrees C were 1.15 +/- 0.03% and 1.13 +/- 0.02%, whereas those of chicks at 25 degrees C were 1.26 +/- 0.03% and 1.27 +/- 0.02%. In experiment 2, the influences of temperature and dietary Arg on the Met requirements of young broiler chicks were investigated. The basal diet was based on corn (53.45%), soybean meal (37.72%), and poultry fat (23% of CP and 3.20 kcat/g of ME). Experiment 2 had a 6 x 2 factorial arrangement, with the basal diet (0.35% Met and 1.52% Arg) supplemented with 6 levels of dietary Met (0, 0.05, 0.1, 0.15, 0.2, or 0.3%) and 2 levels of dietary Arg (0 and 1.0%). When chicks were fed a corn-soybean meal basal diet containing 1.52% Arg, the Met requirements of young Ross x Ross broiler chicks raised at 35 degrees C were 0.43 +/- 0.02% and 0.43 +/- 0.03%, whereas those of chicks at 25 degrees C was 0.43 +/- 0.01% and 0.48 +/- 0.03%, based on body gain and FCR data, respectively. When Arg levels were increased to 2.52%, the Met requirement of young Ross x Ross broiler chicks was greater at both temperatures (P < 0.05). The requirements of chicks raised at 35 degrees C were 0.50 +/- 0.02% and 0.49 +/- 0.02% and at 25'C were 0.59 +/- 0.03% and 0.57 +/- 0.02%, based on body gain and FCR data, respectively. Temperature and amino acid balance may both affect the amino acid requirements of broilers.