For a long time, the high phosphorus (effective phosphorus) in feed is a big misunderstanding of China's feed industry. This not only wastes valuable feed phosphorus resources, increases feed costs, but also exacerbates environmental pollution. I have had deep contact with more than 100 feed enterprises across the country, and I have more exchanges with industry colleagues. I know that no matter whether it is pig or poultry, or premix, concentrate or full price, effective phosphorus is generally better than needed. The amount is about 20-30% higher. I hope that everyone will express their views, evaluate the need for effective phosphorus in livestock and poultry, and correctly guide the feed industry out of this misunderstanding.
Phytase is a great miracle in the enzyme preparation industry in the 1990s. Studies have increasingly shown that the use of sufficient phytase in pig and chicken diets significantly reduces the availability of inorganic phosphorus and reduces phosphorus excretion in feces while improving the utilization of calcium, zinc, protein/amino acids and energy. The role of phytase and the factors affecting its activity are described in detail on the following pages, which are only briefly summarized. Phytic acid (cyclohexanoic acid hexaphosphate or phytic acid) or phytate is an essential component of all seeds, and seeds will rapidly deposit phytic acid during the ripening phase. Phytate is mainly found in wheat bran in wheat; phytate in corn is mainly found in the germ; the phytate and protein binding of leguminous seeds are distributed throughout the seed. The bioavailability of phosphorus in both grain and oilseed products by pigs and chickens is low, only 10-30%.
The phytic acid molecule has a high phosphorus content (28.2%) and a great chelating potential. Under neutral pH conditions, many insoluble divalent or polyvalent cation salts can be formed. At the pH of the small intestine, 1 mole of phytic acid can bind an average of 3-6 moles of calcium to form an insoluble phytate, so that neither phosphorus nor calcium can be utilized by animals. Zinc, copper, cobalt, manganese, iron and magnesium can also be chelated, with zinc and copper having the highest binding affinity to phytate. This combination causes these minerals in the small intestine to be absorbed by the animal. Zinc is the mineral with the greatest bioavailability of all trace elements affected by phytate. Phytic acid also has side effects on dietary protein and amino acids, and phytic acid also inhibits the activity of proteolytic enzymes such as pepsin and trypsin in the gastrointestinal environment. Under acidic conditions, the phosphate group of phytic acid can bind to an amino group (such as a lysine residue, a histidine residue, and an arginine); under neutral conditions, the carbonyl group of some amino acids can pass through the phytic acid. A combination of valence or polyvalent metal compounds. Phytic acid-protein salts or phytic acid-mineral-protein salts all reduce the availability of proteins.
The development of phytase to today is already a very mature product. There are at least four commercial microbial phytase enzymes on the market today, two of which are derived from recombinant Aspergillus fermentation and two from extracts of Aspergillus culture.
Aspergillus phytase has two optimal pH points: pH = 2.5 and pH = 5.5, respectively. Poultry sac and anterior stomach are the main phytase active sites. For pigs, the stomach is the main phytase active site, while the phytase activity in the small intestine is lower because of the jejunum and ileum. The pH (6.5-7.6) is not suitable for the action of phytase activity, or because the proteolytic enzyme in the small intestine hydrolyzes the phytase.
The proportion of phytase instead of calcium hydrogen phosphate (non-granular feed): Adding 100g/t phytase (ie 500IU/kg phytase) to the feed can increase the digestibility of phytate phosphorus in the feed by about 20%. Generally, the corn gluten-type hens feed contains about 0.35-0.4% of phytate phosphorus, about 0.4-0.5% of chicken feed and pig feed, and 500 IU/kg of phytase, which can release about 0.07-0.08% of available phosphorus. (equivalent to 4.0-4.7kg of calcium hydrogen phosphate), chicken and piglets can release about 0.08-0.1% of available phosphorus (equivalent to 4.7-5.8kg of dibasic calcium phosphate). Add 100 grams of phytase per ton of feed (ie 500 IU / kg), increase the cost of 0.8-1 yuan, can save the cost of adding calcium hydrogen phosphate 10.0-14.5 yuan (calculated according to 2.5 yuan / kg), the rate of return is 1:12.5 the above. At the same time, it is also possible to save the cost of adding trace elements by optimizing the formula.
The following is my experience in using phytase for reference:
Piglet: add 120-130g/t phytase +3.0-3.5kg/t calcium hydrogen phosphate; medium pig: add 120-130g/t phytase +1.5-2.0kg/t calcium hydrogen phosphate; big pig: add 120-130g / t phytase, generally do not add calcium hydrogen phosphate; seed sow: add 120-130g / t phytase +5.0-6.0kg / t calcium hydrogen phosphate; chicken: add 120-130g / t plant Acidase + 5.5-7.0kg / t calcium hydrogen phosphate; laying hens: adding 120-130g / t phytase, generally do not add calcium hydrogen phosphate.
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