Effect of chili meal (Capsicum frutescens LINN.) on growth performance, stress index, lipid peroxidation and ileal nutrient digestibility in broilers reared under high stocking density condition

The experiment was designed to investigate the effects of chili meal on growth performance, stress index, lipid peroxidation and ileal digestibility in broilers under high stocking density. Total of 664 day-old male broiler, Cobb-500, were randomly allocated into 10 treatments of 4 replicates each. The first two treatments were fed control diet and raised under normal and high stocking density to serve as stress-negative and stress-positive control groups, respectively. The rest were raised under high stocking density. Feed containing 2.5mg/kg avilamycin and 250mg/kg α-tocopheryl acetate were fed to Groups 3 and 4 respectively. Groups 5 and 6 were fed chili granules. Groups 7 and 8 were fed chili powder. Groups 9 and 10 were fed chili meal. Chili diet fed to Groups 5, 7, and 9 contained 20mg/kg capsaicin while the diet of Groups 6, 8 and 10 contained 30mg/kg capsaicin. Capsaicin concentration, stability and nutrient composition of the three chili forms were analyzed prior to the experiment. Data of growth performance, heterophil/lymphocyte (H/L) ratio, plasma malondialdehyde (MDA) concentration, and nutrient digestibility were collected and determined at the age of 21 and 41 days. Chili meal showed the lowest stability. Growth performances of birds in Groups 5–10 were better than Group 1 (P<0.001) and 2 (P<0.029) during the starter period; however, only final body weight was significantly higher (P=0.035) than the stress-positive control group during the finisher period. Among the chili-fed groups, chili meal group significantly showed higher average daily gain (ADG) and lower feed conversion ratio (FCR) than the chili granule group (P=0.014 and P=0.027) but they were not significantly different from those of chili powder group. All forms of chili diet significantly reduced MDA in birds to the level that could compare to stress-negative control group but the level was not significantly different from the avilamycin and α-tocopheryl acetate groups. No significant differences were found in ileal nutrient digestibility. The levels of capsaicin had no effects on all observed parameters. In conclusion, chili meal up to 78.9g/kg in diet did not show any adverse effects. Under high stocking density, chili meal group had FCR comparable to avilamycin group and better than α-tocopheryl acetate group. The capsaicin level of 20mg/kg was sufficient to show beneficial effects on growth performance and lipid peroxidation. It is recommended that chili meal should be used promptly when stored at 30°C with 75% relative humidity.