Effect of different levels of dietary crude protein on the growth performance and carcass characteristics of commercial broilers at different phases of growth

Abstract

An experiment was conducted to find out the effect of different levels of crude protein in broiler diets during different phases. i.e., pre starter (0-11d), starter (12-21d) and finisher (22-42d). 360 day-old broilers (Vencobb) were procured from a commercial hatchery and fed either high or low dietary CP diets during pre-starter (23 and 21%) , starter (21 and 19%) and high, moderate or low CP diets during finisher ( 18.5, 17.5 and 16.5%) phases, for a total of 12 possible treatment combinations at d 42. The results showed that the broilers fed low levels of CP ( 21 and 19 %) had significantly(P less than 0.05) higher body weight gain (BWG) and feed intake (FI), and better feed efficiency over the diets with high levels of CP during pre-starter and starter phases (23 and 21%, respectively). The higher (18.5%) level of protein in the finisher phase showed higher BWG and best FCR compared to the lower levels (17.5 and 16.5%). Carcass characters were not influenced by the variation in dietary CP level tested except the abdominal fat weight which was significantly higher in broiler fed low CP diet compared to those fed higher levels of CP during all three phases. The results indicated that the broilers fed low CP diets supplemented with critical amino acids (21 and 19%) had beneficial effect on the growth performance during pre-starter and starter phase. The broilers showed an ability to respond to increase in dietary CP levels during finisher phase.