Take advantage of natural phytase in feed grain

Phosphorus in feed for laying hens is a difficult balancing act for organic egg producers, who are not allowed to use feed with synthetically derived phytase. On the one hand, the hens must have sufficient phosphorus available for bone mobilization and eggshell strength, on the other hand, the amount of phosphorus in the manure must be minimized for the sake of the environment.

Grains contain phytase; rye, triticale and wheat more than barley and oats. Phytase in-crease phosphorus availability for poultry, but is degraded during heating processes, and therefore phytase activity in pelleted finished feed is low or non-existent. To ensure a suf-ficient supply to the organic hens in practice, a larger amount of total phosphorus is added to the feed.

In the project Optimal utilization of natural phytase activity in feed grain, the Innovation Centre for Organic Farming has studied whether the content of phosphorus in finished feed can be lowered without compromising the hens' needs, and whether it is possible for producers with own feed production to increase utilization of the natural content of phytase in cereals.

Phosphorus in finished feed can be lowered

Organic advisor of egg production Niels Finn Johansen, Innovation Centre for Organic Farming, estimates that the safety margin that feed producers work with when it comes to phosphorus is ample. The studies show that total phosphorus in finished feed for hens over 30 weeks of age can be lowered to between 5.5 and 6.0 g/kg feed, whereas it has traditionally been around 6.7.

The test was carried out on a farm with 11 production barns, nine of which used experi-mental feed with a lower phosphorus content.

Low phosphorus level - high degree of management

Under current legislation, feed producers may not refrain from heat treating the grain in mixtures and thus preserve the naturally occurring phytase in the feed. This is only an op-tion for producers with own feed production. During the project, 11 farms have collected data on phosphorus and phytase in feed, and shell strength in eggs and bone strength has been studied. The farms use their own grain to different degrees, and the variation between flocks was extremely big on all parameters. There is a direct link between phos-phorus supply and bone- and eggshell strength.

According to Niels Finn Johansen, some egg producers choose to use a very low phos-phorus content in the feed. It requires a high phytase activity in the feed and management at a high level, and in that situation, there is no room for failure.

Conclusions of the project

• The safety margin applied so far for phosphorus in feed for organic hens has been greater than necessary.
• Total phosphorus in factory-produced feed for organic hens over 30 weeks of age can be lowered to between 5.5 and 6.0 g/kg feed corresponding to 3.2 g available phosphorus per kg feed.
• By using own, unheated grain, one can maintain significant phytase activity, in-creasing the availability of the feed’s natural phosphorus content.
• The natural phytase activity (200-500 RTD/kg feed) in the study has not been high enough to compensate for the very low phosphorus content that some egg producers use.
• There is a direct link between phosphorus supply and bone- and eggshell strength.
• Strategic calcium supply at the end of the day may be an important method to reduce the need for phosphorus for deposition and mobilization of calcium from the bones during eggshell formation.

Read more

Report: Optimal utilization of natural phytase activity in feed grain for organic hens (pdf, 5 pages)

The content of phytase in winter grains has been studied in organic national experiments and is referenced in  this article.