The effects of vitamin E in crude palm oil on growth performance, lipid peroxidation and tissue vitamin E concentration of broilers

Abstract

An experiment was studied to investigate the effects of vitamin E in crude palm oil on growth performance, lipid peroxidation and tissue vitamin E concentration of broilers. Total 576 day old male Ross 308 broiler chicks were randomly allocated into 6 treatments which composed of 6 replicates of 16 birds each. Corn-soybean meal basal diets with 8% lard which was adjusted vitamin E level according to the recommended requirement (50 mg/kg diet) by adding [alpha]-tocopheryl acetate, was used as a control diet. Crude palm oil (CPO) was substituted to lard at the level of 0, 2, 4, 6, and 8 % respectively. Positive control was conducted to evaluate vitamin E efficacy in CPO by supplementation of [alpha]-tocopheryl acetate 100 mg/kg control diet. Diets were calculated to meet Ross requirement. On day 21 and 42 of the experiment, body weight and feed intake were recorded and six broilers in each treatment group of each period were randomly selected. On day 21, blood and liver were collected while blood, liver, breast and thigh meat were collected on day 42. Thiobarbituric acid-reactive substances (TBARS) and vitamin E concentration of all forms were analyzed in plasma, liver, breast and thigh meat. Relationship between vitamin E concentration in diet and tissues were calculated by linear regression. TBARS were determined on days 4 and 7 and drip loss was measured on day 2, 4, 6 and 8 day in breast and thigh meat in controlled-chilled room at 8 degree celcius. The results demonstrated that growth rate and feed conversion ratio were not significant difference among treatment groups in both periods (P>0.05). An increasing of CPO level increased tocopherol and tocotrienol concentration in liver breast and thigh meat when compared to control group (P<0.05). Broilers fed with CPO 8% had highest deposition of tocotrienol while the positive control group has highest tocopherol concentration in tissue. Form of vitamin E deposition in tissues, [alpha]-tocopherol had highest follow by [alpha]-tocotrienol, [gamma]-tocopherol and [gamma]-tocotrienol respectively. The tocopherols, tocotrienols and total vitamin E concentration in all tissues showed the positive relationship with crude palm oil level in diet (P<0.05). Inclusion of CPO as a vitamin E source at the level of 4% or more in diet decreased TBARS in plasma at the age of 21 and 42 day (P<0.001) when compare to control and CPO at the level of 6 and 8% fed group were not difference with positive control group. No significant difference of TBARS was found in liver and breast meat while thigh meat of CPO fed groups were significant difference when compared to control group(P<0.001) but not significant difference with positive control group. During storage, inclusion of CPO as a vitamin E source in diet decreased TBARS and CPO from the level of 4% and onward decreased drip loss in breast and thigh meat when compare to control group and not significant difference with positive control group.