Table 1.
Relativity of three tiers of digestible branched-chain amino acid concentrations to lysine (100) in experimental diets1 containing 11.0 g/kg digestible lysine and 175 g/kg crude protein applied to a 3-factor, 3-level Box-Behnken design.
Table 2.
List of experimental treatments for Ross 308 off-sex male broiler chickens from 7 to 28 days post-hatch.
Table 3.
Composition of experimental diets (g/kg).
Table 4.
Nutrient specifications (g/kg) of experimental diets where values for digestible amino acids are tabulated.
Table 5.
Analysed concentrations of protein (N) and amino acids in experimental diets.
Fig 1.
Linear relationship (P = 0.022; r = -0.284) between dietary leucine concentrations and weight gain where: Weight gain(g, 7-28d) = 1487–3.905 × digestible leucine(g/kg).
Fig 2.
Quadratic relationship (P = 0.014; r = 0.358) between dietary leucine concentrations and FCR from 7 to 28 days post-hatch where: FCR(g/g, 7-28d) = 1.956 ‒ 0.0719 × digestible leucine(g/kg) + 0.0024 × digestible leucine(g/kg)2.
A dietary leucine concentration of 14.99 g/kg corresponds to the minimum FCR of 1.418 (g/g).
Fig 3.
Linear relationship (P = 0.022; r = -0.284) between dietary isoleucine concentrations and relative abdominal fat-pad weights where: Relative fat pad weight(g/kg) = 15.42–0.251 × digestible isoleucine(g/kg).
Table 6.
Effects of dietary treatments on growth performance and relative abdominal fat-pad weights from 7 to 28 days post-hatch.
Table 7.
Effects of dietary treatments on nutrient utilisation from 24 to 27 days post-hatch.
Fig 4.
Response surfaces showing the relationship between weight gain and dietary digestible branched chain amino acids in male broilers from 7 to 28 days post-hatch.
Fig 5.
Response surfaces showing the relationship between feed conversion ratio (FCR) and dietary digestible branched chain amino acids in male broilers from 7 to 28 days post-hatch.
Fig 6.
Response surfaces showing the relationship between dietary digestible valine and isoleucine on relative fat pad weights (28 days post-hatch) and apparent metabolisable energy (AME) from 24 to 27 days post-hatch.
Fig 7.
Response surfaces showing the relationship between nitrogen corrected apparent metabolisable energy (AMEn) and dietary digestible branched chain amino acids in male broilers from 24 to 28 days post-hatch where the maximum AMEn (12.42 MJ/kg) could be estimated at 15.74 g/kg digestible leucine.
Fig 8.
Response surface showing the relationship between dietary digestible leucine (Leu) and valine (Val) on nitrogen (N) retention from 24 to 27 days post-hatch where the lowest N retention was estimated at 15.25 and 10.50 g/kg Leu and Val respectively.
Table 8.
Polynomial fitted model (P < 0.05) for growth performance from 7 to 28 days post-hatch and nutrient utilisation from 24 to 27 days post-hatch.
Table 9.
Polynomial fitted model (P < 0.05) equations for growth performance from 7 to 28 days post-hatch and nutrient utilisation from 24 to 27 days post-hatch.
Fig 9.
Polynomial fitted model surface response influence (P = 0.011; r = 0.313) of dietary digestible (dig.) leucine (leu) and dig. valine (Val) on mean amino acid (AA) digestibility coefficients where: Mean AA digestibility(coefficient) = 0.0906 × dig.
Leu(g/kg) + 0.2153 × dig. Val(g/kg)− 2.879 × 10−3 × dig. Leu(g/kg)2–0.0103 × dig. Val(g/kg) 2–1.0478. The maximum mean digestibility coefficient of 0.793 was estimated at a combination of 15.74 and 10.47 g/kg of digestible leucine and valine respectively.
Fig 10.
Linear relationship (P < 0.001; r = 0.560) of dietary digestible isoleucine on isoleucine digestible coefficient where: Digestible isoleucine(coefficient) = 0.6443 + 0.0164 × digestible isoleucine(g/kg).
Table 10.
Effects of dietary treatments on apparent ileal digestibility coefficients of essential amino acids at 28 days post-hatch.
Table 11.
Effects of dietary treatments on apparent ileal digestibility coefficients of non-essential amino acids at 28 days post-hatch.
Table 12.
Polynomial fitted model (P < 0.05) for apparent digestibility coefficients of amino acids at 28 days post-hatch.
Table 13.
Polynomial fitted model (P < 0.05) equations for apparent digestibility coefficients of amino acids at 28 days post-hatch.
Table 14.
Estimated maximum digestibility coefficients by dietary leucine and valine levels at 28 days post-hatch.
Table 15.
Effects of selected dietary treatments on free amino acid systemic plasma concentrations (μg/mL) at 27 days post-hatch.
Table 16.
Effects of dietary treatments on apparent disappearance rates (g/bird/day) of essential amino acids at 28 days post-hatch.
Table 17.
Effects of dietary treatments on apparent disappearance rates (g/bird/day) of non-essential amino acids at 28 days post-hatch.