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on September 24, 2009

Feed cost savings via the phytase matrix

Phytase is increasingly used in poultry feed but are its benefits fully exploited?

Escalating demand for cereal grains for human and animal production, coupled with the increasing use of grains for biofuel production, have affected the supply and demand ratio for these commodities, which in turn, has resulted in an ever-increasing price for poultry feed ingredients.

Feed constitutes about 70% of total costs in poultry production. Additionally, the sky-high price of energy, protein and phosphorus sources, which constitute some 90-98% of poultry feed, depending on the type and stage of the bird, has led to lower profits for farmers and even huge losses in many areas. Energy, protein and phosphorus cost savings can be among the most-effective solutions to improve farm profitability.

Over the last decade, the inclusion of microbial phytase has increased markedly, mostly with the objective of reducing phosphorus ingredient levels, principally dicalcium phosphate (DCP), in poultry feed.

The further benefits of using phytase, however, have been largely overlooked, probably because of the original objective behind phytase development a reduction in the levels of phosphorus excretion in manure. Additionally, the higher cost of DCP, and reasonable cost of vegetable feed ingredients at the time that phytase was introduced, may have added to the DCP cost-saving focus.

When phytase is used in feed, it is often included without proper application of the phytase matrix. Many producers do not state their products' matrix values, leading to incorrect application.

Using phytase from a reliable source with appropriate matrix values can maximise feed cost savings through the reduction of DCP, and a reduction in energy sources, such as maize, bajra, sorghum, broken rice and protein sources including soyabean meal, groundnut meal, sunflower meal and rapeseed meal in poultry feed.

Phytase as an anti-nutritional factor

Poultry feed largely consists of seed like cereal grains and products derived from seed like oilseed meals and cereal by-products.

Vegetable feed ingredients contain phytic acid or phytate. Phytic acid is a naturally occurring organic complex, generally regarded as the primary storage form of phosphorus and inositol in the seeds of plants.

Phytate is a polyanionic molecule with the potential to chelate positively charged nutrients, which is almost certainly fundamental to the anti-nutritive properties of phytate. It binds not only to phosphorus but also to some other vital nutrients, making them unavailable to the body. Consequently, phytate also acts as an anti-nutritional factor.

Phytate binds with phosphorus, thus reducing phosphorus bioavailability. It also forms phytate-metal complexes with other minerals including calcium, magnesium, iron and zinc reducing their bioavailability.

Phytate decreases protein digestibility by forming protein-phytate complex and it binds free amino acids, making them unavailable. Additionally, it may bind starch and also strongly inhibits the activity of amylase, thus reducing energy utilisation. Ca-phytate and lipids may be involved in the formation of metallic soaps in the gut, which are major constraints on the utilisation of energy derived from lipids, particularly saturated fats.

Appropriate application of the phytase matrix

Phytase hydrolyses phytates and improves the utilisation of not only phosphorus but also calcium, energy and proteins/amino acids. The term "phytase matrix" describes the amount of these nutrients to be released, or their equivalency values, with the addition of phytase to feed. The appropriate application of the phytase matrix values is highly important to maximise feed cost savings through the reduction of respective nutritional sources.

The phytase matrix may vary depending on the phytase source or the manufacturing process. Available brands have various matrix values.

With the application of appropriate phytase matrix values, the energy ingredients such as maize, sorghum, wheat, bajra; protein ingredients such as soyabean meal, groundnut extraction (GNE) and phosphorus ingredients such as DCP and bone meal can be reduced through the addition of cheaper ingredients, including de-oiled rice bran (DORB) and limestone powder (LSP).

Table 1 and Table 2 give an indication of the correct application of phytase matrix values to maximise feed cost savings. (Click here for Table 3.)

The calculation shows that along with the reduction of DCP by 6.4kg, we can reduce maize by 39.3kg and soyabean meal by 14.1kg due to the addition of phytase and cheaper ingredients such as LSP and DORB. This can save $8.93 per 1,000kg of broiler, chicks and grower feed.

Similarly, in 1,000kg of layer feed, with the addition of phytase, LSP and DORB, savings of up to $7.83 are possible through the reduction of DCP by 7.7kg, maize by 26.5kg and soyabean meal by 10kg.

Limestone powder is added to match the calcium content in feed, since reduction of DCP also causes a reduction of calcium content. DORB is a comparatively cheaper ingredient usually added as filler, but it provides some nutrients, which should be considered when formulating feed.

Similarly, depending on the nutrient composition of the respective feed ingredients and correct phytase matrix values, modifications in the feed formulation can be carried out by reducing the content of any other vegetable, energy and protein sources in order to reduce feed cost.

Phosphorus is the third-most-expensive nutrient in poultry feed. Giving equal importance to energy, protein and phosphorus through the application of reliable phytase with a clear matrix value can maximise cost savings and improve profitability.

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