A trial was conducted with fifty pigs (Landrace x Large White), barrows and gilts, from 15 to 30 kg, in the initial growing phase to determine the digestible sulfur amino acids requirements. The animals were allotted to a completely randomized experimental block design, with five treatments (0.502, 0.530, 0.558, 0.586, and 0.614% of digestible methionine plus cystine), five replicates and two animals (one male and one female) per experimental unit. It was observed quadract effect of treatments on daily weight gain, that increased up to the level of 0.582%, on feed:gain ratio, that decreased up to the level of 0.588%, and on daily feed intake, that increased up to the level of 0.579%. The intake of digestible methionine and cystine linearly increased as the dietary levels of digestible methionine plus cystine increased. It was observed quadract treatment effect on fat deposition, that increased up to the level of 0.556%, but no treatment effect on protein deposition was detected. It was concluded that the digestible sulfur amino acid requirement for barrows and gilts from 15 to the 30 kg is of 0.582 and 0.588%, that corresponds to a digestible methionine plus cystine:digestible lysine ratio of 63%, respectively, for the highest weight gain and lowest feed:gain ratio.
genotype; initial phase; digestible amino acid; requirement
