Effect of feeding higher concentrations of limiting amino acids on performance slaughter variables and nitrogen retention in broiler chicken fed graded levels of toasted guar (Cyamopsis tetragonoloba) meal

Abstract

1. An experiment was conducted to study the effect of supplementing higher concentrations (100% vs. 110%) of critical amino acids (CAA) on performance (body weight gain – BWG, feed efficiency – FE), slaughter variables and nitrogen retention in broiler chicken (1–6 weeks of age) fed graded levels of toasted guar meal (TGM) as a protein source in diets. 2. The TGM was included at five graded concentrations (0, 50, 100, 150 and 200 g/kg) in iso-caloric and iso-protein diets with either the recommended concentration (100%) of CAA (lysine, total sulphur amino acids, threonine, tryptophan and valine) or at 10% higher (110%) concentration. A metabolism trial of 3-day duration was conducted during 6th week of age to study nitrogen retention. 3. The TGM levels and CAA concentration at 21 or 42 d of age did not influence BWG, FI and FE. BWG was not affected with inclusion of TGM up to 100 g/kg in starter and overall production (1–42 d of age) phases. The FE improved with TGM supplementation during starter phase, while at the end of experiment (42 d), FE was depressed by inclusion of TGM in dose dependant manner. All performance variables improved with increase in concentration of CAA from 100% to 110%. 4. Breast meat weight improved and abdominal fat weight reduced with higher levels of CAA in diet. Retention of nitrogen reduced with increase in level of TGM in broiler diet. Increasing concentrations of CAA in diet improved nitrogen retention. 5. It was concluded that TGM could be incorporated up to 100 g/kg with 100% CAA and up to 150 g/kg with 110% CAA without affecting performance. Increasing CAA concentration (110%) in diets significantly improved BWG and FE (21 and 42 d), breast meat weight and nitrogen retention in broiler chicken.