INCLUSION OF OXIDIZED VEGETABLE OIL IN BROILER DIETS - ITS INFLUENCE ON NUTRIENT BALANCE AND ON THE ANTIOXIDATIVE STATUS OF BROILERS

Over a period of 4 wk, 24 10-d-old broiler hens were fed diets contain ing 11% vegetable oil (9% rapeseed oil, 2% soybean oil), which was add ed either fresh (1 meg O-2/kg oil) or oxidized (156 meg O-2/kg oil). T he effects of the dietary treatments on nutrient digestibility were ex amined in a balance experiment. The antioxidative status of the animal s was evaluated using plasma concentrations of thiobarbituric acid-rea ctive substances (TEARS), erythrocyte hemolysis in vitro, selenium-dep endent and selenium-independent activity of glutathione peroxidase in liver cell cytosolic fractions, and concentrations of tocopherols and other fat-soluble compounds with antioxidative properties (lutein, bet a-carotene, and retinol) in plasma and various tissues (skeletal muscl e, cardiac muscle, liver, and abdominal fat). Compared to the fresh oi l, the concentrations of linoleic and linolenic acid were slightly low er in oxidized oil. The concentration of alpha-tocopherol in the diet with fresh oil was an average of 80.8 mg/kg diet, whereas the diet wit h oxidized oil only provided 44 mg/kg. The dietary selenium content av eraged 0.48 mg/kg in both diets. During the experiment, none of the an imals showed symptoms of diarrhea or vitamin E deficiency. The intake of oxidized oil caused a growth depression after 2 wk. The retention o f fat (P = 0.07), energy (P = 0.09), and alpha-tocopherol (P < 0.01) w as lower in the group fed oxidized fat. Furthermore, these animals sho wed significantly higher plasma concentrations of TEARS (P < 0.01), an d lower concentrations of tocopherols, lutein, beta-carotene, and reti nol in plasma and tissues.