Phytate degradation in pigs and poultry

PROF. DR. MARKUS RODEHUTSCORD, UNIVERSITY OF HOHENHEIM, GERMANY

With a finite supply of rock phosphates on the planet, plant-based phosphates are being used as an alternative source in feed applications. The breakdown of phytates can be negatively affected by calcium and phosphate which are commonly added as supplements in pig and poultry diets. In a summary of the talk he gave at the Huvepharma® seminar, Professor Rodehutschord reminds us of the dramatic improvements that phytase enzymes have on phosphate breakdown.

All living organisms depend on the continuous supply of phosphates. Because rock phosphates are a non-renewable resource and its global stores are limited, application of feed phosphates should be reduced through utilizing plant phosphorus sources such as phytate. Phytate is the major storage form of phosphate in plant seed and is a byproduct of the food and energy sectors.

Broiler chickens appear to have a higher potential of phytate breakdown in the digestive tract than pigs (Fig. 1). This is likely related to endogenous enzymes produced by epithelial cells or by bacteria present in the gut. Supplements of calcium (Ca) and phosphate added to the diet reduce phytate breakdown in the digestive tract. Supplementation with a phytase enzyme can increase digestive phytate breakdown drastically (Fig. 2). Some of the phosphate remains entrapped in lower inositol phosphate esters, even at high levels of phytase supplementation. However, another part of the phytate is completely dephosphorylated, resulting in the release of myo-inositol by phytase supplementation (Fig. 3).

Phytase supplementation can also increase the digestibility of amino acids. Meta analyses of literature data indicate that this is in the range of 1 – 2 percentage points and that this effect is lower in pigs than in broilers. Well-adjusted concentrations of phosphate, Ca, and phytase supplements allow for an increased efficiency of phosphorus (P) utilization in broilers and pigs that helps save finite rock phosphate resources for future generations.

Figure 1. Precaecal disappearance of phytate (InsP6) in broilers and pigs fed diets with low P and Ca concentrations

Source: Rodehutscord and Rosenfelder, 2016

Figure 2. Precaecal disappearance of phytate (InsP6) in broilers fed maize-soybean meal diets and different combinations of P, Ca, and phytase

Source: Sommerfield et al., 2018a

Figure 3. Concentration of myo-inositol in digesta of the crop (left) and ileum (right) of broilers fed different levels of phytase or a supplement of myo-inositol

Source: Sommerfield et al., 2018b

References

Rodehutscord, M. and Rosenfelder, P. (2016): Update on phytate degradation pattern in the gastrointestinal tract of pigs and broiler chickens. In C.L. Walk, I. Kühn, H.H. Stein, M.T. Kidd, M. Rodehutscord (eds.): Phytate destruction – Consequences for precision animal nutrition. Wageningen Academic Publishers, 15-32.

Sommerfeld, V., Künzel, S., Schollenberger, M., Kühn, I. and Rodehutscord, M. (2018b): Influence of phytase or myo-inositol supplements on performance and phytate degradation products in the crop, ileum, and blood of broiler chickens. Poultry Science 97, 920-929, doi 10.3382/ps/pex390

Sommerfeld, V., Schollenberger, M., Kühn, I. and Rodehutscord, M. (2018a): Interactive effects of phosphorus, calcium, and phytase supplements on products of phytate degradation in the digestive tract of broiler chickens. Poultry Science 97, 1177-1188, doi 10.3382/ps/pex404