Níveis de metionina + cistina total para frangos de corte de 22 a 42 dias de idade mantidos em ambiente termoneutro

The experiment was carried out to determine the requirement of methionine + cystine (met + cys) for broilers from 22-to-42-day-old kept under thermoneutral environment (23.5°C). A total of 240 Avian Farm male broilers, with 827 g average initial weight were distributed in a randomized experimental design with five levels of met + cys (0.659, 0.704, 0.750, 0.796, and 0.841%), six replications and eight birds per experimental unit. The increase of met + cys level influenced positively feed: gain ratio, met + cys intake, drumstick absolute weigh and thigh relative weight. No effect of met + cys levels was observed on the final weight, weight gain, feed intake, breast, carcass and abdominal fat absolute and relative weight, thigh absolute weight, and drumstick relative weight, or for relative and absolute weight of the organs (heart, liver, gizzard, proventriculus, lung and intestines). The level 0.727% met + total cys (0.661% digestible met + cys), corresponding to the ratio met + cys/total lys of 70% (72% for digestible lys) gave the best feed: gain ratio for male broilers kept in thermoneutral environment.