| In vegetable feedstufs, often seeds or by-products of seed processing, phytate is the main storage form for phosphorus. Since actions (e.g. Ca.Zn,and Fe) can be complexed to phytate, it is also a storage from for such minerals, Especially during germination plants use these nutrients. Also proteins, starch and possibly fat can be complexed to phytate. For degradation of phytate, special enzymes are required: phytases. during germination, the plant produces such an enzyme. Animals, however, cannot produce phytases. Therefore, phosphorus from phytate is poorly available to monogastric animals (in this proposal: pigs and poultry). Microbial phytase added to the feed improves phosphorus availability. These effects are well established and abundantly recorded in the scientific literature. By the complexing of protein to phytate, the rate and/or extent of amino acids digestibility may be reduced. When the complexing of protein to phytate, the rate and/or extent of amino acids digestibility may be reduced. When phytase hydrolyses the phosphate groups from the phytate, this binding ability is gone, too. In different trials and literature reviews, it has been shown that phytate addition to feed may improve animal performance. The improved digestion of P, amino or cationic minerals (e.g. Ca, Zn) cannot explain this effect fully. Therefore, energy utilisation may be improved by phytate degradation, too. the effect on energy utilisation can be explained in different ways: increased energy digestion, a better utilisation of the absorbed energy, and/or a decreased energy requirement for maintenance or for production. The latter may be due to a reduced productiobn of endogenous proteins, like digestive enzymes, or by a change in homeostasis, e.g. of the acid-base-balance. The quantification of the effect of phytase addition tom phytate-containing feed on anmino acid and energy utilisation is of importance, since these nutrients hold high value for the feed producing industry. Knowledge of the effect of phytase on these nutrients permits the industry to optimise the input/output balance of essential nutrients, thus to maximise nutrient utilisation and, consequently, to minimise nutrient losses, which is positive for the natural environment and for animal health. Objectives: To investigate whether phytase addition to a feed can improve availability and utilisation of protein (amino acids) and energy in pigs and poultry. Quntify such an effect, and clarify the mode of action. Hypotheses: * Phytase addition to a diet containing phytase improves amino acid digestibility. * Phytase addition to feed improves energy utilisation. * Phytase addition to feed in an increased absorption and excretion of minerals, and consequently in an adaption of the acid-base balance, and in a reduced production of endogenous proteins. |
