The experimentwas conduced to determine the requirements of digestible methionine + cystineof barrows with high potential genetic for lean meat deposition from 60 to 95kg. Seventy hybrid commercial barrows with the same genetic pattern, with initialaverage weight of 60.00 ± 1.13 kg, were allotted to a randomized experimentalblocks design with five digestible methionine and cystine levels (0.440; 0.464;0.488; 0.512 and 0.536%), corresponding, respectively, to 55.0; 58.0; 61.0,64.0 and 67.0% of methionine and cystine: digestible lysine in the diet, sevenreplicates and two animals by experimental unity. The experimental diets andthe water were ad libitum supplied until the end of experimental period whenthe animals reached an average weight of 94.95 ± 0.50 kg. The digestiblemethionine and cystine levels of ration influenced the daily weight gain thatlinearly increased up to the level of 0.536 %, and feed:gain and lean meat amount,which improved by a quadratic way up to the levels of 0.506 and 0.507%, respectively.The digestible methionine and cystine intake linearly increased with the increasedigestible methionine and cystine levels in the diet. There was no effect ofthe digestible methionine and cystine levels on feed intake, backfat thickness,carcass yield and percentage lean meat in the carcass. Barrows from 60 to 95kg with high potential genetic for lean meat deposition in the carcass requiring0.507% digestible methionine and cystine, corresponding to digestible methionineand cystine:digestible lysine in the ration of 63.0% for a better feed:gainand lean meat amount in the carcass.
