Influence of dietary calcium and calcium phosphorus ratio on the effectiveness of phytase

The response to a given level of supplemental phytase will be influenced by dietary Ca level and or Ca P ratio, dietary P level and dietary phytate level (Lei et al., 1994 Dungelhoef and Rodehutscord, 1995 Kornegay, 1996b). A high molar ratio of Ca to phytate in the diet can lead to the formation of extremely insoluble Ca phytate complexes under intestinal conditions, making the phytate molecule inaccessible to phytase. The presence of such strong complexes could explain the apparent inactivity...

Influence of microbial phytase on energy metabolism

Thompson and Yoon (1984) indicated that, in the native state, phytate could complex with starch. Rajas and Scott (1969) reported that the apparent metabolizable energy (AME) of cottonseed meal and soybean meal for chicks was improved following treatment of the meals with a crude phytase preparation from Aspergillus ficuum. Later, Miles and Nelson (1974), using chicks and a similar product, reported improvements in the AME value of cottonseed meal and wheat bran, but not soybean meal, when...

Occurrence and structure of phytate

The major ingredients in commercial pig and poultry diets are seeds (cereal grains) or products from seeds (oilseed meal and grain by-products). A large portion (60 80 ) of the P in these ingredients occurs in the form of phytates, the salts of phytic acid (Table 10.1). Phytic acid, myo-inositol 1, 2, 3, 4, 5, 6 hexakis dihydrogen phosphate, is an essential component of all seeds. Seeds rapidly accumulate phytic acid during the ripening period (Asada et al., 1969). The location of phytate in...

Influence of microbial phytase on amino acids and nitrogen bioavailability

Phytate can bind with protein amino acid (AA) at low and neutral pH (De Rham and Jost, 1979 Cosgrove, 1980 Anderson, 1985 Thompson, 1986 Fretzdorff etal., 1995). Phytate-protein AA complexes may occur in foodstuffs in the native state, and may be formed in the upper gastrointestinal tract. Complexing of phytate with proteolytic enzymes may also occur in the upper gastrointestinal tract. These potential phytate-protein complexes thus may reduce the utilization of proteins and amino acids. If...

Sources of phytase

Currently, there are at least four commercially available microbial phytases, two obtained by fermentation of a genetically modified Aspergillus Natuphos and Novo phytase , and two obtained by extraction of media with Aspergillus Finase and Alltech phytase . Patents influence the availability of these in some countries. Most products are available in a powder or granular form and as a liquid. The genetic information for both Natuphos and Novo phytase originated from A. ficuum and was...

Introduction

Phytase may well be the miracle enzyme of the 1990s, as soybeans were described as the miracle crop for producing high quality plant protein in the 1940s. Dietary addition of microbial phytase or the inclusion of high phytase ingredients in pig, poultry and fish diets is now well documented to release a large portion of the naturally occurring phytate P, and thus greatly reduce the amount ofinorganic P that must be added to meet the animal's P requirement. The net result is a reduction in P...

Pigs

Similar findings have been reported in pigs. Officer and Batterham 1992 and Khan and Cole 1993 reported that microbial phytase improved the apparent ileal and total tract digestibility of crude protein by 2.3-12.8 units. Using cannulated pigs in two studies, Mroz et al. 1994 and Kemme 1998 reported that microbial phytase 800 and 900 U kg-1, respectively enhanced the apparent ileal digestibility of N and most amino acids. Added microbial phytase generally enhanced the total tract digestibility...

Potential for binding nutrients

Phytate Protein

The phytic acid molecule has a high P content 28.2 and chelating potential Fig. 10.1 to form a wide variety of insoluble salts with di- and trivalent cations at neutral pH Vohra etal., 1965 Oberleas, 1973 Cheryan, 1980 . One mole of phytic acid can bind an average of 3 6 mol of Ca to form insoluble phytates at the pH of the small intestine. Formation of insoluble phytate makes both Ca and P unavailable. Zn, Cu, Co, Mn, Fe and Mg can also be complexed, but Zn and Cu have the strongest binding...