Effect of supplemental vitamin E on the performance of growing-finishing pigs fed stored versus freshly harvested barley and on the storage stability and eating quality of frozen pork

A 2 × 4 factorial experiment was conducted with 80 growing-finishing pigs to evaluate effects of barley storage (stored barley harvested the previous year or freshly harvested barley) and supplemental vitamin E (0, 40, 80 or 160 mg/kg as all-rac-a-tocopheryl acetate) on pig performance and the storage stability and eating quality of frozen pork. Pigs were fed isoenergetic barley-soybean meal diets and vitamin E was rationed on the top of feed, a 2-d dose at a time. Stored and freshly harvested barley contained 33.5 and 31.2 mg/kg of vitamin E in the beginning and 33.0 and 38.7 mg/kg at the end of the study, respectively. Supplemental vitamin E had a quadratic effect on pig growth (P < 0.05), the greatest weight gains being observed with 40 mg/kg of supplemental vitamin E in both barley diets. Vitamin E supplementation increased linearly serum (P < 0.001) and quadratically back fat a-tocopherol (P < 0.01). Plasma gluthathione peroxidase activity increased as pigs grew older (P < 0.001), and at slaughter it decreased linearly with supplemental vitamin E (P < 0.05). Dietary vitamin E supplementation did not affect the content of thiobarbituric acid reactive substances (TBARS) or the organoleptic quality of pork stored frozen (-18°C) for 16 weeks. The TBARS content of pork increased with time (0 to 8 d) thawed meat was displayed under fluorescent light at 8°C (P < 0.001) which was detected as a poorer taste. In conclusion, supplemental dietary vitamin E above 40 mg/kg feed does not improve pig performance nor the storage stability or eating quality of frozen pork when freshly harvested or stored barley from good harvest conditions is fed to growing-finishing pigs.;