The Role of Vitamins as Co-factors and Antioxidants in Immunity and Gut Health
Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, AB
The importance of vitamin nutrition in poultry feeding has been recognized for decades, yet precise vitamin requirements for modern, high producing have not been investigated. Because of their low inclusion rates, vitamins have a relatively small impact on the cost of feed. Many vitamins lose activity over time or under high-temperature feed processing. Vitamins, especially the water-soluble vitamins, are tolerated at many times the established minimum recommended levels. Finally, the standard minimum recommendations published in sources such as the 1994 Nutrient Requirements of Chickens (NRC) are based largely on achieving maximum growth or egg production, rather than the optimization of product yield, quality, or bird health. Therefore commercial nutritionists generally including large safety margins for each vitamin.
Most vitamin requirement studies in poultry were completed before the 1980’s; few classical vitamin requirement studies have been conducted since then. Major advances in efficiency of meat and egg production have changed the context for vitamin nutrition. Increased production efficiency without concomitant increases in vitamin supplementation implies an actual reduction in vitamin intake relative per unit of product produced. The global move towards antibiotic-free poultry meat production, and extended laying cycles for layers increases the importance of the immune system, and gut health in particular. The role of vitamins with particular impacts on immunity and gut integrity (specifically vitamins A, D and E) will be reviewed in the context of opportunities in the face of the challenges of modern poultry production.