Nutrient digestibility in poultry (OK-Net EcoFeed practice abstract)

Feed rations that consider nutrient digestibility can better utilise regional feedstuffs, optimising health, body maintenance and production requirements. They help to improve animal welfare, lower costs and reduce nitrogen pollution from compensatory feeding. Practical recommendations • Regular analysis of all dietary components is recommended for a reliable nutrient profile of feed rations. • To optimise the use of home-grown feed, the nutrient content of forage should be considered in diet formulation. • High quality protein fulfils amino acid (AA) requirements, particularly lysine, cysteine and methionine. • Diets formulated on digestible amino acids (DAA) are more effective than those formulated using total AA content. • Digestibility of AAs is affected by dietary fibre content and the presence of anti-nutritional factors and protease inhibitors. • Adding permitted enzymes to the diet can stimulate the digestibility of all nutrients, particularly protein and complex carbohydrates. They may also help birds to break down anti-nutritional feed components • Starch (simple carbohydrates) is the primary energy source for poultry and is generally well digested. • Complex carbohydrates in grains (wheat, barley, rye and oats) increase viscosity which negatively affects digestive processes and nutrient absorption. • Fibre is poorly digested but helps to slow down the passage rate of other nutrients in the gut, improving digestion of all nutrients. A high intake of fibre can risk a reduction in total intake so restriction may be necessary. • Fat digestibility is linked to the presence of other dietary components, and minerals in particular. • Fat improves feed palatability and is required for energy and the absorption of fat-soluble vitamins A, D, E, and K. • Age of bird influences fat digestibility with older birds being better able to digest fat than younger birds. • As with fibre, fat can reduce feed passage rate (influenced by fat type and quantity) through the gut, enhancing digestion of all nutrients. • Processing feeds can improve overall digestibility although finely milled feed reduces protein digestibility and pancreatic enzyme activity compared to coarser feed. • Heat treatments can reduce anti-nutritional factors and, e.g., steam pelleting, can improve carbohydrate digestibility