the effect of energy sources and levels on performance and breast amino acids profile in cobb 500 broiler chicks

the present study conducted to investigate the effect of energy sources and levels on performance and breast meat amino acids profile in cobb 500 broiler chicks. a total of 600 1-day-old cobb 500 broiler chicks with an average weight of 39 ± 0.50 g were randomly divided into five treatments. each treatment was further divided into four replicates. chicks were fed a basal diet based on corn and energy level was same as cobb 500 manual as control group, the basal diet with 3% lesser energy than control (t1), the basal diet with 6% lesser energy than control (t2), the basal diet based on corn and fat level according to cobb 500 instruction manual (t3), the basal diet based on corn and fat with 3% upper energy (t4) for 42 days. results showed that the best and the worst performance were for t4 and t2, respectively. also, feed intake of chicks increased significantly in t4. body weight gain was also significantly higher in the treated group with the basal diet based on corn and fat with 3% upper energy (t4). as result relevant although the lowest feed conversion ratio was for control and t3 on 14 and 28 days but also it was at the lowest on t3 on 42 days. the breast muscle function and amino acid profiles showed that there were significant effects between arginine (arg), glutamic acid (glu), proline (pro), alanine (ala), aspartic acid (asp), serine (ser), glycine (gly), isoleucine (ilo), lysine (lys), valine (val) and phenylalanine (phy) amino acids (p≤0.01). the highest level of amino acids (g/g dm basis) was for glu, asp, arg, lys, ser, phe and pro. in conclusion, it seems that inclusion of higher energy level than broiler nutritional requirements recommendation for cobb 500 chicks could give better performance and affect the quantity and quality of their breast meat and its amino acids profile. in order to achieve higher weights, more energy is needed than the recommendation of cobb 500, but to have better feed conversion ratio the recommended energy level is the best.