The experiment was conducted to evaluate the effect of protease enzyme supplementation on carcass performance, meat quality and laying performance of Ben Tre Noi female chickens at 14-22 weeks of age. The experiment was arranged in a completely randomized design with 4 treatments and 11 replicates and each replicate was 2 females at 14 weeks of age. The experimental groups were as follows (1) the control (control) using only the feed of the basal diet (KPCS) without the addition of protease enzyme; (2) Pro100 includes KPCS supplemented with 100 mg protease/kgfeed; (3) Pro125 including KPCS supplemented with 125 mg protease/1kgfeed; and (4) Pro150 including KPCS supplemented with 150 mg protease/kgfeed. The experimental results showed that the body weight of chickens at the beginning and the end of the experiment was not statistically significant (P>0.05). There was a statistically significant difference in the absolute weight gain of chickens (P0.05). However, L * 30p on breast meat color at 30 minutes after slaughter was highest in Pro125 (43.16) and lowest in control (36.68). Similarly, L*d48h of thigh meat at 48 hours after slaughter was highest in Pro100 (41.04) and lowest in Pro125 (36.68) and Pro150 (37.57). Egg production, laying egg rate, egg weight, age at first laying, egg mass, feed consumption and feed conversion ratio were not significantly different among treatments (P>0.05), however, Pro100 tended to improve the laying egg rate and egg mass compared to control and other supplementation treatments.

Keywords: protease enzyme, weight gain, meat color, hen