Low-protein amino acid-supplemented diets in broiler-chickens: effects on performance, carcass characteristics, whole-body composition and efficiencies of nutrient utilisation

摘要: Two concurrent trials were conducted to investigate the influence of low-protein amino acid-supplemented diets on performance, carcass characteristics, whole-body composition and efficiencies nutrient utilisation by male broiler chicken from age 3 6 weeks. The first trial comprised five isoenergetic (13.0 MJ kg−1) containing 225 (control), 210, 190, 172 or 153 g kg−1 crude protein (CP) supplemented with essential acids (EAAs) meet minimum National Research Council recommendations. In second a composite mixture non-essential (NEAAs) was added lower-CP (ie 210–153 g kg−1) such that they became isoproteinous (N × 6.25) 225 g kg−1 control. Neither lowering dietary CP nor NEAA supplementation had any significant weight gain relative weights various cuts. However, chicks fed lowest-CP consumed more feed (P ≤ 0.05) poorer conversion efficiency (FCE). enhanced FCE control levels. Whole-body compositional analysis showed increased (P ≤ 0.01) total body fat in linear fashion (P ≤ 0.001; r = −0.72). Equalising maintaining identical energy/protein ratio) did not correct for deposition. Total (g kg−1) without supplementation. Dietary energy, retention (PRE) ratio (PER) efficient lower-protein diets, while significantly decreased N utilisation. Reducing excretion highly r = 0.73). nutritional environmental implications deposition one hand other low-protein-fed chickens are discussed need harmonise these apparently conflicting interests is emphasised. © 2000 Society Chemical Industry