INFLUENCE OF HOUSING CONDITlONS AND TYPE OF FINISHING FEEDS ON THE OXIDATIVE STABILITY OF BROILEKCHICKEN MUSCLES

Abstract

Twenty-four Anak broiler chickens were used in a 2 x 2 factorial experiment to study the effect of rearing chickens in cages or on deep litter, and finishing them either on grower or finisher mash, for two weeks prior to slaughter, on muscle lipid content and extent of oxidation during cold storage. The cold storage treatments were 1, 4 and 8 days of refrigeration, and re-freezing of frozen muscle samples which had been thawed once. Lipid oxidation in muscles was measured using the thiobarbituric acid reactive substances (TBARS) test. Chickens finished on finisher mash had higher eviscerated weight (P>0.05), belly fat depot (P>0.05) and muscle lipid content (P<0.001) than those on grower mash. These on average were: eviscerated weight;75.23 vs. 75.08'%, live weight (LW), belly fat; 14.25 vs. 11.67 g/kg LW, and lipid content of breast; 5.65 vs 3.73'%,, thigh; 7.2s vs 5.64'%,. Muscles from chicken reared in cages had higher lipid content (P>0.05) t hat1 those reared on deep litter (averaged 5.1 vs. 4.28% for breast; 7.02 vs. 5.901Xifl, or thigh) and the thigh muscle contained higher lipid content than the breast muscle. Oxidative susceptibility of muscles creased with increasing lipid content (thigh > breast; cage > deep litter; finisher mash > grower mash). Muscle lipid oxidized also increased (P~0.001) with increasing length of refrigerated storage, and thawed and then re-frozen muscles oxidized more than those that were constantly frozen.