The aim of this study was to evaluate the performance and the body composition of swine fed diets with low crude protein, but supplemented with amino acids. Thirty-eight young castrated swine were used, out of which eight were slaughtered in the beginning of the experiment. The remaining 30 swine were allotted in five treatments and six replications using a randomized block experimental design. The treatments consisted of rations with 10, 12, 14 and 16% protein, and a treatment of ration with 10% protein supplemented with nitrogen from a nonessential amino acid source. Swine fed with rations 12, 14 and 16% protein had greater daily gain and better feed conversion. The protein deposition was bigger in swine feeding rations 16 and 14%, in comparison to those fed rations with 10% protein. The rate of lipid deposition was lower in swine fed on ration with 16% protein, and higher in swine fed ration with 10% protein. The crude protein reduction levels of the ration until 12% limit do not influence the performance and the retention of protein in swine, since diets are supplemented with essential amino acids. However, the protein level decrease of the ration increases body fat.
animal nutrition; ideal protein; protein deposition
