Biological systems are subject to oxidative stress and free radical attack. Free radicals and reactive oxygen species are formed as by-products of aerobic metabolism and redox reactions that occur naturally in living organisms. When there is an imbalance in their production and elimination they can cause extensive tissue damage. In order to protect itself from damage of ROS and free radicals the body has antioxidant defence systems in place which consists of enzymatic- and non enzymatic systems. Vitamin A and Vitamin E are two antioxidants included in the diet that form part of these defence system and are well known for their ability to prevent lipid peroxidation in cell membranes of tissue.
Bioflavonoids are polyphenolic compounds found naturally in plants and have been shown to contain strong antioxidant properties and can be added to the diet to help protect the body from oxidative damage. Biored® is a commercial antioxidant product made from bioflavonoids that is added to animal feed to serve this purpose.
The main objective of the study was to determine if Biored® can partially replace the synthetic vitamins A and E included in broiler chicken diets. Broiler growth performance, liver vitamin A and E concentrations, blood oxidation levels, meat quality and carcass traits and shelf life of chicken thigh meat were measured. Replacing half of the vitamin A and E requirement of the chickens with Biored® could also be a cost saving practice as vitamin A and E are expensive to supplement in the diet. According to ADVIT Animal Nutrition Pty Ltd, vitamin E (500 IU) is sold for R82.55/kg and vitamin A (1000 000 IU) sold at R360.85/kg. Currently Biored® is sold at R35.00/kg to feed manufacturers.
Eight different dietary treatments were used that included different Biored® concentrations and either standard levels of synthetic vitamin A and E, only half these levels or no additional vitamin A and E. The dietary treatments were set up as follows, Treatment 1, 100% vitamin A and E, 0 g/ton Biored®; Treatment 2, 0% vitamin A and E, 0 g/ton Biored®; Treatment 3, 0% vitamin A and E, 150 g/ton Biored®; Treatment 4 100% vitamin A and E, 150 g/ton Biored®; Treatment 5, 50% vitamin A and E, 0 g/ton Biored®; Treatment 6, 50% vitamin A and E, 100 g/ton Biored®; Treatment 7, 50% vitamin A and E, 150 g/ton Biored®; Treatment 8, 50% vitamin A and E, 200 g/ton Biored®. In treatment 1 with the 100% vitamin A and E inclusion levels the actual cost of vitamin A in the grower diet for this trial amounts to R1.26 and for vitamin E, R2.92. Treatment 3 that only contains 53g Biored® and no vitamim A and E the total cost of Biored® amounts to R1.86. In treatment 8 the diet contains 70.7g Biored® at a cost of R2.47, while half of the vitamin A (1.8g) and vitamin E (141.5g) amounted to R0.63 and R1.46 respectively. These calculations show that the inclusion of Biored® could potentially decrease the cost of the diet due to full or partial replacement of vitamin A and E.
The body weight of broilers on day 35 that received half the vitamin A and E specification with different incremental levels of Biored® did not differ significantly from the Positive Control group (100% vitamin A and E and no Biored®) and with increasing level of Biored® in the feed the weights of the groups seemed to increase as well, though the differences were not significant. The cumulative feed intake was improved when diets with 50% of vitamin A and E specification was supplemented with Biored® as well as the average daily gain over the whole 35 day trial period. Biored® did not have a vitamin A and E sparing effect in the liver.
Biored® helped improve oxidative stress in the blood of broilers at the end of the growth trial when added at the highest concentration of 200 g/ton. Carcass or portion weights in birds were not affected by the dietary treatments. Meat quality factors including drip loss, cooking loss and shear force in breast meat portions was also not affected by the inclusion of Biored®. The shelf life of thigh meat portions was also not affected by the addition of Biored® to the feed. The absence of vitamin A and E in the feed caused the most deterioration overall.
More research has to be done to determine the exact mode of action of the flavonoids present in the product and to what extent the compounds are metabolized and absorbed into the system of the birds.
Dissertation (MSc Agric)--University of Pretoria, 2016.