REQUIREMENT OF YOUNG-PIGS FOR APPARENT ILEAL DIGESTIBLE TRYPTOPHAN

Five growth trials involving a total number of 420 young pigs were per formed to study the tryptophan requirement during the live weight rang e of 20 to 40 kg. Five levels of L-tryptophan addition (0.0, 0.15, 0.3 0, 0.45 and 0.60 g kg(-1)) were evaluated using a basal control diet, containing 162 g kg(-1) crude protein (CP) and 1.65 g kg(-1) tryptopha n. The control diet was supplemented with lysine, methionine + cystine , threonine, isoleucine, valine and histidine to assure that only tryp tophan was limiting pig performance. The experimental diets were fed a d libitum as pellets. The requirement for total tryptophan was found t o be approximately 2:10 g kg(-1) for optimal weight gain and maximum e fficiency of feed utilization, in a diet containing 9.5 MJ kg(-1) net energy. This value corresponds with approximately 1.77 g kg(-1) appare nt ileal digestible tryptophan.