Metabolizable energy levels and L-arginine supplementation in diets for broilers under heat stress from 29 to 42 days of age

Oliveira, David Henrique deCruz, Fábio LouresSobrane Filho, Sérgio TurraAlves, Breno ResendeAbreu, Márvio Lobão Teixeira deNaves, Luciana de PaulaRodrigues, Paulo Borges

The objective of this study was to evaluate the L-arginine supplemental effects for broilers in the final rearing phase (29 and 42 days), during which they were exposed to heat stress and fed diets with different metabolizable energy levels. Performance, carcass parameters, and physiological and biochemical parameters related to lipid metabolism were evaluated. A completely randomized design was used, in a 3 × 2 factorial arrangement, corresponding to three metabolizable energy levels (3000, 3150, and 3300 kcal/kg) in diets supplemented or not with L-arginine (0.66%). Eight replicates composed by eight broilers each (experimental units; boxes) per treatment were evaluated, totaling 48 experimental units. Performance was evaluated in the period from 29 to 42 days old, and carcass and blood parameters were measured at 42 days old. L-arginine supplementation improved feed conversion and blood profile, mainly due to the reduction of total and LDL-cholesterol levels. Broilers that received 3300 kcal/kg of metabolizable energy showed the greatest weight gain, regardless of supplementation or not with arginine. The dietary supplementation with 0.66% of L-arginine for heat-stressed broilers can be recommended, regardless of the feed energy level.(AU)

1. blood parameters
2. carcass yield
3. performance
4. energy conversion
5. functional amino acid