Abstract

R. Vakili and A. A. Rashidi

The objective of this experiment was to characterize the relationship between dietary fat and antioxidant supplementation on performance, fatty acids profile and lipid oxidation of thigh meat stored under refrigeration in broilers under heat stress. The chicks with a similar body weight were equally assigned to one of the two controlled-environment chambers from 21 to 56 day of age. The birds fed diets as: 1) basal diet supplemented with 5% saturated fatty acid, 2) basal diet supplemented with 5% unsaturated fatty acids (2% canola oil plus 3% fish oil); and 3) The second diet supplemented with antioxidant (100 IU vitamin E and 50 mg/kg zinc); that birds received this 3 diet in two temperature (22 and 32°C). Results showed that feed conversion ratio was not influenced by fat type, but on live body weight and feed Intake had significant effect (P<0.05). High environmental temperature showed deleterious effects including: reduction of feed intake, and live body weight and increasing of feed conversion ratio. Proportion of omega-6 to omega-3 (n-6/n-3) of thigh was increased and polyunsaturated fatty acids (PUFA) decreased in heat exposed and tallow-fed chicks. Whereas the proportion of omega-6 to omega-3 (n-6/n-3) of thigh was decreased and polyunsaturated fatty acids (PUFA) increased in chicks fed with canola and fish oils. Fat content and gross energy of thigh in heat exposed and canola and fish oils with antioxidant fed chicks were higher than other treatments. Proportion of omega-6 to omega-3 (n-6/n-3) of thigh was decreased and polyunsaturated fatty acids (PUFA) increased in chicks fed with canola and fish oils. Inclusion of canola and fish oils supplementations increased lipid oxidation of thigh muscle based on TBARA values. Thiobarbituric acid reaction substances (TBARA) values of thigh muscle in chicks fed canola and fish oils reared under heat stress was higher than other treatments. Increasing dietary antioxidants decreased TBARA values of thigh muscle.