Supplementation with curcuminoids and tuna oil influenced skin yellowness, carcass composition, oxidation status, and meat fatty acids of slow-growing chickens
The present study aimed to determine the effects of dietary curcuminoids combined with tuna oil on the growth performance, meat quality, thiobarbituric acid reactive substances (TBARS) values in the plasma and raw meat, and fatty acid profile of chicken meat. A total of 480 21-day-old mixed-sex slow-growing chickens was assigned to a completely randomized design model with 6 treatments and 4 replicates (pens) per treatment. The basal diet based on corn-soybean and 4% tuna oil was used as the negative control. The experimental diets comprised the basal diet supplemented with curcumin removed turmeric oleoresin to provide 20, 40, 60, or 80 mg/kg curcuminoids (CUR-20, CUR-40, CUR-60, and CUR-80, respectively) or dl-α-tocopheryl acetate at 200 ppm as the positive control (E-200). Finally, the vacuum-packed carcasses were stored frozen at −20°C for 3 mo to examine the effect of curcuminoids on changes in the TBARS values and fatty acid composition of the breast and thigh meat. Increasing the levels of curcuminoids tended to improve the feed conversion ratio (linear, P = 0.065) and significantly increased the proportion of breast fillet (linear, P = 0.037) and the yellowness of the skin of both the breast (linear, P = 0.016) and the thigh (linear, P = 0.023). The curcuminoids exhibited antioxidant properties, but their effect was not dose dependent. The CUR-20 and CUR-40 treatments increased the linoleic acid content but decreased the C22:6n-3 (DHA) content of the breast meat. The CUR-60 treatment inhibited oxidation (measured by TBARS) in the chicken meat similarly to dl-α-tocopheryl acetate but had no effect on the proportion of DHA in the breast or thigh meat. Auto-oxidation occurred in the breast meat but not in the thigh meat during the 3 mo of frozen storage. The present study showed that a suitable level of curcuminoids in the diet of slow-growing chickens was 60 mg/kg.