Metabolisable energy levels for stress broilers under thermal stress

ABSTRACT The research was carried out with the objective of evaluating different levels of metabolisable energy (3050, 3100, 3150, 3200 and 3250 kcal.kg-1) in the diet of 22-to-42-day-old broilers kept in an environment of thermal stress. Three hundred male chicks weighing 814.7 g initial average weight were distributed in a completely randomised design with five treatments, six replications and ten birds per experimental unit. Feed metabolisable energy levels did not influence (P > 0.05) the performance variables of feed conversion, daily weight gain and daily feed intake in the two phases studied. There were no statistical differences in carcass yields: carcass, chest, thigh, drumstick, heart, wing and back. Differences were observed for the two variables gizzard yield and abdominal fat. A linear increase in the percentage of abdominal fat with an increase in energy levels in the diet was observed. The 3100 kcal.kg-1 level of metabolisable energy is the level indicated by this research because it results in lower abdominal fat content and lower cost per kilo of feed.