Dietary lysine concentrations from deficient to excessive and the effects on broiler chicks.

1. An experiment was designed to test the response of broiler chicks (0-21 d) to dietary lysine concentration. Concentrations ranged from 9.9 to 14.4 g of lysine per kg diet when energy was 13.4 MJ ME/kg. 2. Estimates of the concentration of lysine needed for maximum body weights gain, food consumption and gain:food ratio were calculated using two statistical methods. An average of these estimates was 12.0 g lysine/kg diet to 21 d of age. 3. Chicks given 13.9 or 14.4 g lysine/kg diet were negatively affected by these concentrations. The decreases in average weight gain, food consumption and food efficiency were caused mainly by several chicks that developed severe leg problems and were much smaller than their pen mates. Chicks with no leg problems gained weight as rapidly as chicks receiving optimal amounts of lysine.