An study was conducted to evaluate the influence of reduction of crude protein (CP) levels and amino acid supplementation in diets on the performance of castrated swines (Landracex Large White) maintained in a termoneutral environment. Fifty crossbreed piglets (average initial body weight of 30.2 kg) were allotted to a completely randomized experimental design with five treatments (17, 16, 15, 14 and 13% CP) and five replications and two animals per experimental unit. Experimental diets and water were fed ad libitum up to the end of the experiment, when the animals reached the average weight of 60.2 kg. Temperature in the room was kept at 22.0ºC and the relative humidity at 82.8%, corresponding to a Black Globe-Humidity Index (BGHI) of 69.2. Reduction of dietary CP level affected body weight gain (WG) of the animals, those animals fed diet with 17% CP showed smaller WG than the animals fed diet with 15 and 14% CP. Feed intake (FI) and feed:gain ratio were not affected by treatments. Reduction of CP level increased the protein and fat deposition in the carcass and reduced the total nitrogen excretion. The level of crude protein of diet to castrated swines from 30 to 60 kg maintained in a termoneutral environment could be reduced from 17 to 13% with no effect on performance, since diets are supplemented with essential limitant amino acids.
amino acids; termoneutral environment; nutrition; swine
