Lysine requirement of broilers as influenced by environmental temperatures

Two experiments were conducted to determine the influence of 15.6 and 29.4 degrees C. environmental temperatures on 2- to 4-week broiler lysine requirements. Weights for 4-week-old cockerels were maximum when either 1.10% dietary lysine in the 15.6 degrees C. environment or 1.00% dietary lysine in the 29.4 degrees C. environment were fed. Feed was used more efficiently by 4-week old cockerels fed either 1.10% dietary lysine in the 15.6 degrees C. environment or 0.95% dietary lysine in the 29.4 degrees C. environment. Plasma free lysine concentrations from 4-week-old cockerels increased as dietary lysine increased. Total plasma free amino acid concentrations from chicks grown in a 15.6 degrees C. environment were approximately 25% greater than from chicks grown at 29.4 degrees C. Total plasma free amino acids for 4-week-old cockerels peaked when 1.05% dietary lysine in the cool environment and 0.95% dietary lysine in the warm environment were fed.