Feed Additives - Vemo 99

The role of phytate phosphorus

What is phytate? Simply, this is the structure of an inositol ring where six phosphate (P) groups are attached. That negatively charged (anionic) structure is usually accompanied by cations (positively charged compounds) - proteins and/or starch.

The role of phytate is to bind:
•    phosphorus and store it for use by the developing plant embryo
•    cations and release them after germination

Phosphorus in animals is associated in phytate and is almost unused, because non-ruminant animals lack endogenous phytase, so the phytate phosphorous cannot become available. In birds, this phytate phosphorus get released into the environment, which can create a problem for the breeders. Since this litter phosphorous is exceeded in the soil, it can accumulate over time. Currently, the soil in some areas needs very little phosphorus. Thus, concerns about the environment lead to restrictions for litter dispersion.

Problems with phytate phosphorus

Leaving aside issues concerning public affairs, phytate phosphorus in feed for non-ruminants poses several problems:

•    Phosphorous locked in the form of phytate is practically unused.
•    Potentially, phytate can bind to other nutrients such as ions, amino acids and starch.
•    Phytate violates the activities of endogenous digestive enzymes.

All of the above led to the classification of phytate in the category of anti-nutritive factors.

Usually phytate phosphorus varies between 0.25 to 0.40% in the feed mixtures for birds. While studying the utilization of phytate phosphorous without the addition of phytase, in the literature one can find examples of low, medium or relatively high. The ability to make use of the phytate phosphorous seems to depend on many factors related to the type of bird and the nutrition.

In general, it can be said that birds do not receive enough phosphorus for optimum growth and productivity, if inorganic phosphorus is not added.

Feed ingredients of plant origin usually contain phytate quantity that may vary from year to year depending on the growing conditions. Unfortunately, there is no quick and easy method for measuring phytate, because it is not present in the same place in the seeds of various plants. The addition of phytase depends on the location of phytate in the plant materials used for the feed. Also, this has an effect on the extent to which phytase will interact with other exogenous enzymes, in particular enzymes whose targets are polysaccharides (NSP) located in plant cell walls.

The terminology concerning phosphorus is not always the same. The scientific community describes phosphorus as total available, utilized, retained and non-phytate. Although similar, these descriptions do not mean the same thing. Confusingly, the terminology is not always correct for the state of phosphorus. In order to increase the accuracy of the measurement, the following order can be followed: general

In North America bioavailable phosphorus is commonly used as a term, while in Europe digestible phosphorus is more often used.