Effect of enzymatic cottonseed protein on serum biochemical profiles, slaughter performance, meat quality, and volatile flavor compounds of broilers

This study aimed to determine the effects of enzymatic cottonseed protein (ECP) on serum biochemical profiles, slaughter performance, meat quality, and volatile flavor compounds in broilers. A total of 400 yellow-feathered broilers were randomly assigned to five treatment groups, 10 broilers per replicate. Broilers in the control group received a diet primarily composed of corn-soybean meal. In the four treatment groups, dietary protein from soybean meal was partially replaced with ECP at substitution levels of 25% (25% ECP group), 50% (50% ECP group), 75% (75% ECP group), and 100% (100% ECP group). The experimental period lasted for 63 d. Compared with the control group, the 25% and 50% ECP groups exhibited significantly lower serum glucose levels (P < 0.05), with ECP having no significant effect on other serum biochemical profiles; the 100% ECP group had a significantly higher slaughter rate of broilers (P < 0.05); the 75% ECP group significantly increased both the half-eviscerated and breast muscle rates of broilers (P < 0.05); and the 50% ECP group significantly increased the cooking loss of breast muscle (P < 0.05); however ECP exhibited no significant effect on other meat quality profiles of broiler breast muscle. In broiler muscles of the 75% ECP group, methional, 2-methyl butanal-D content, (E)-2-hexenal-D, and ethyl acetate increased significantly, whereas hexanal-D content decreased significantly (P < 0.05), resulting in a notable reduction in off-flavor compounds and notable improvement in the overall flavor quality, that produced a more balanced favorable effect on the flavor characteristics of broiler muscle. In conclusion, dietary substitution with 75% ECP improved broiler slaughter performance and enhanced the flavor characteristics of breast muscle without significantly affecting serum biochemistry or muscle quality. These findings support the feasibility of substituting up to 75% of dietary protein with ECP in broiler diets.