Mike Tokach: "The amount of phytase used in pigs has been increasing"

Thanks Mike for this interview and very interesting answers on this topic. Since you mention phytases within the responses, would you be so kind as to give an opinion on what are your thoughts on three topics: i) high dosages of phytase, effect beyond P and other minerals release/availability; ii) high ZnO dosages, how do you think they would interfere with phytase, what your recommendation would be?; iii) would you say phytases must have a different response depending on the phytate origin?, is there good and solid information out there in this subject?. Many many thanks from Madrid, Rafa.

High doses of phytase have shown benefits in several experiments with nursery pigs. While I believe that some of the benefit is due to release of other nutrients, I also believe that pigs were under their phosphorus requirements in many of these studies. Thus, providing high doses of phytase allows maximum phosphorus release. Thus, there is good evidence that we should consider high doses, especially with young pigs.

Although the data on interactions between zinc oxide and phytase is not entirely clear, I would recommend adding more phytase to the diet and formulating to higher P levels when pharmacological levels of zinc oxide are included in the diet.

On your third question, I am not the best person to answer this question. I initially read your question as phytase origin, but you are asking about the phytate origin. There is some evidence from poultry that phytate origin may have an impact on phytase ability to release P, but the data is very limited and I am not aware of data on the subject in pigs.

Mike.

Mike, many thanks for taking your time answering my questions. All clear. Rafa from Madrid!

Dear Mike, You replied to Rafael Duran that you are not aware of data concerning extrinsic/intrinsic phyteses and the origin of phytate in pigs. I suggest to get more insight in the work of Mroz, Kemme and Jongbloed from Lelystad with regard to this topic. It is obvious that from the commercial point of view - the higher doses of supplemental phytase the better income of the manufacturer. However, from the scientific point of view, we should inform the readers objectively that the effect of extrinsic phytases in the diet is closely interrelated with the level of intrinsic phytases. With friendly regards. Prof. Zdzislaw Mroz from Lelystad

1Kryukov V.S., 2Glebova I.V., 3Antipov A.A. 2019 Evaluation of fitases action in gastrointestinal tract and the use of fitase preparations in animal feeding: a review. Problemy biologii productivnykh zhivotnykh - Problems of Productive Animal Biology, 2019, 2: 19-43. ABSTRACT. Since the beginning of the 60s, phytase preparations, an enzyme from the group of phosphatases, with a predominant affinity for plant phytates, are widely used in the market of feed additives. The aim of this work is to systematize data of the phytase action in vitro and in animals and the effects of diet composition on the availability of phytate phosphorus. The “extraphosphate” effect of phytases and a new explanation of the inhibition of the availability of amino acids by phytates are described. Examples of the use of commercial feed preparations containing phytase are given. Selection of highly active phytase producents among fungi and bacteria and methods of genetic engineering made it possible to create feed phytases, which allows for 30–40% increase in the use of phosphorus from vegetable raw materials. The extraphosphate effect exerted by feeding phytases is expressed by an increase in the available amino acids of the protein and the metabolizable energy of the feed. This fact is widespread and repeatedly confirmed in experiments, however, the explanation of this phenomenon is erroneous, since phytases do not have a proteolytic effect. Authors of the review conclude that the splitting of phytates leads to loss of their ability to block already digested amino acids, causing an increase in their availability. The increase in the amount of available amino acids has led to the erroneous conclusion about the increase in protein digestibility. When choosing phytase feed preparations, it is necessary to take into account their resistance to the proteases of gastrointestinal tract and the stability to thermal effects during the granulation of feed. It is necessary to critically treat the claimed characteristics of the action of enzyme preparations, since they do not always take into account the particular composition of feed. Further studies are needed to study the molecular mechanisms of the extraphosphate action of phytases, causing an increase in the availability of amino acids and metabolizable energy