Energy concentration and protein inclusion in diets for broilers: Effects on growth performance

We studied the effect of inclusion crude protein (CP) and energy concentration in the diet on growth performance, gastrointestinal tract (GIT) traits, and carcass weight in broilers from 0 to 42 d of age. The experimental design was completely randomized with six diets combined as a 2 x 3 factorial with two levels of CP (20 vs. 22%) and three levels of energy (2900, 3000, and 3100 kcal/kg). Each treatment was 4 replicate and the experimental unit was a pen with 20 birds. All diets were based on corn, soybean meal, wheat, and included sunflower oil. For the entire experiment, the inclusion of CP in the diet did not affect growth performance and the other variables studied. From 0 to 42 d of age, increase energy concentration up to 3100 kcal/kg in diet tended to reduce average daily feed intake (ADFI) (P = 0.053) and improve feed conversion ratio (FCR) (P < 0.01) than energy concentration at level of 2900 kcal/kg. However, average daily gain (ADG) was not affect. Most of the benefits of increase energy concentration on broiler growth was observed from 14 to 21 d and 28 to 35 d of age, a period in which energy concentration improved ADFI and FCR (P < 0.01), respectively. On d 42, increase energy levels in the diet did not affect GIT or carcass relative weight, except for the liver relative weight was heavier (P < 0.05) when intermedia energy concentration 3000 kcal/kg was included in the diet. It is concluded that energy concentration were well utilized by broilers, at level of inclusion.