A trial was conducted to evaluate the effect of reduced CP, amino acid-supplemented diets on performance of castrated males swines on high environmental temperature (32 degrees C). A total of sixty crossbred piglets (Landrace x Large White) averaging initial weight of 15.2 kg was allotted to completely randomized experimental design with five treatments (18, 17, 16, 15, and 14% of CP), six replications and two animals per experimental unit. The experimental diets were fed to swine ad libitum until the end of the experiment, when the animals averaged 29.9 kg. The average temperature in the room was maintained in 32.3 degrees C, with relative humidity of 75.9%, corresponding a black globe-humidity index (BGHI) of 82.6. The reduced CP level, amino acid-supplemented-based diets did not affect the evaluated parameters (feed intake, weight gain and feed:gain ratio). No treatment effect on digestible lysine and energy intakes was observed. Gradual reduction on daily nitrogen intake was observed. Decreasing dietary CP levels affected only fat deposition rate. The highest values of relative and absolute weights of liver and stomach and the relative weight of kidneys were observed in the animals fed diets with the highest dietary CP level. It was concluded that the dietary CP level can be reduced from 18 to 14% for castrated piglets from 15 to 30 kg on high environmental temperature, with no effect on performance, since diets are supplemented with the essential amino acids.
