Effects of dietary energy and protein on growth performance and carcass quality of broilers during finishing phase

Abstract

The present study was undertaken to investigate the influence of varying levels of dietary energy and protein on broiler performance and carcass quality of broilers from 22-42 days of age. A total of 720, 22 days old avian broiler chicks were randomly divided into 12 groups, each group had six replicates and each replicate contained 10 birds. These birds were randomly assigned to 12 dietary treatments in a 3*4 factorial arrangement with three Metabolizable Energy (ME) levels (12.55,12.97 and 13.38 MJ kg-1) and four Crude Protein (CP) levels (18.5, 19.0, 19.5 and 20.0%), respectively, from 22-42 days of age. The results showed that: both ME and CP significantly affected on daily gain, feed efficiency and body weight of 42 days of age (p<0.05); ME levels significantly affected on feed intake (p<0.05) while CP not affected (p>0.05). However, there were no significant interaction in BW, average daily gain, feed intake between dietary ME and CP; dietary ME significantly affected on semi-eviscerated percentage, dressing percentage, leg meat percentage and abdominal fat (p<0.05). Higher level of dietary ME (13.38 MJ kg-1) significantly increased abdominal fat percentage when compared with lower ME (12.55 and 12.97 MJkg-1). Breast meat percentage was increased by dietary CP (p<0.05);L* of both leg meat and breast meat was not affected by dietary ME and CP (p>0.05), b* of both breast meat and leg meat was increased with increasing dietary ME (p<0.05). Both a* and b* were not affected by dietary CP; pH of breast meat was increased by dietary ME while not affected by dietary CP. The Water-Holding Capacity (WHC) of breast meat was decreased by dietary ME but the effect was not significantly (p>0.05). WHC of leg meat was increased by dietary ME (p<0.05). The results of present research indicated that the optimal dietary ME requirement of broilers from 22-42 days of age is 12.97 MJkg-1 and the CP requirement is 19.0-20.0%. © Medwell Journals, 2012.