The effect of different levels of energy and protein in finisher diet on performance, carcass yield and blood serum lipids of broiler chickens

This experiment was conducted to investigate the effect of different energy and protein levels in finisher diet on performance، carcass yield and blood serum lipids of broiler chicks during 42 days. In this experiment 1080 one day old ROSS 308 male broiler chicks raised on floor pens. A randomized complete design with a 3×3 factorial arrangement was used with 4 replicates and 30 male broilers in each replicate. The experimental diets consist of three levels of metabolizable energy (2700، 3000 & 3300 Kcal/Kg) and three levels of crude protein (10% lower، based on &10% higher than the recommended level of Ross 308 broiler requirement in each level of energy) were offered during 29-42 days of age. Results of this experiment indicated that increasing dietary metabolizable energy level significantly reduced feed intake (P<0. 05)، body weight gain and feed conversion ratio significantly improved (P<0. 01)، also the energy and protein intake significantly increased and protein efficiency ratio decreased (P<0. 01). The concentration of VLDL significantly decreased by increasing dietary energy level from 2700 to 3300 Kcal/Kg (P<0. 05). Increasing dietary crude protein level significantly increased body weight gain and improved feed conversion ratio (P<0. 01)، significant increase of energy efficiency ratio، protein intake and decrease of protein efficiency ratio were observed (P<0. 01)، also feed cost per Kg of gain and abdominal fat significantly decreased (P<0. 05). Interactions of energy and protein on feed intake (P<0. 01)، energy intake (P<0. 05) and protein intake (P<0. 01) were significant. Results of this experiment indicated that 3300 Kcal/Kg for energy level and 10% higher than Ross 308 broiler recommended level for protein in finisher diet improved performance of Ross 308 broiler chickens and reduced the cost of production.