Effects of increasing levels of dietary L-Leucine on growth performance, carcass traits and blood parameters of male broilers in the grower period

The effects of increasing levels of L-leucine supplementation on performance, carcass traits, breast meat production and determination of digestible leucine requirement broilers during the grower period (15 to 30 days) using 240 Ross males broiler chickens in a completely randomized design with six dietary treatments (five repetitions and eight chicks per repetition) was investigated. Treatments include; a basal diet with 1.53% digestible leucine and five diets containing 1.63, 1.73, 1.83, 1.93, and 2.03% digestible leucine by adding synthetic L-leucine to the basal diet. By increasing the levels of digestible Leucine, body weight gain, carcass and breast muscle percentage were increased, but feed conversion ratio and abdominal fat percentage were decreased (P<0.05). The response trends to increasing levels of digestible leucine were quadratic for weight gain, feed conversion ratio, the relative weight of carcass, relative weight of breast muscle and relative weight of abdominal fat ( P<0.05). Due to the better fit of the quadratic model to the response criteria, digestible Leucine requirements were estimated at 1.70, 1.72, 1.724, and 1.735% for body weight gain, feed conversion ratio, the relative weight of carcass and breast muscle; respectively. Based on the average of these estimates, the suggested digestible Leucine requirements of broilers in the grower period is 1.72%.

Keywords: Breast yield, Broilers, Carcass traits, Growth Performance, L-leucine.

Abstract published in Journal of Animal Production, Volume 22, Issue 3, Summer 2020, Pages 391-406.