Not all canola meal responds the same to phytase

The paper, written by scientists from the University of Illinois, USA, was published recently in the Journal of Animal Science.

Evaluating phosphorus digestibility

In a university press release, it was explained that most of the phosphorus in canola meal is bound to phytic acid, and microbial phytase is often added to diets to help make more phosphorus available to pigs.

Hans H. Stein, professor in the university’s Department of Animal Sciences, led a project to evaluate phosphorus digestibility in canola meal processed in different ways. His team fed growing barrows diets containing:

• Conventional canola meal (CM-CV);

• Canola meal processed at a high temperature (CM-HT);

• Canola meal processed at a low temperature (CM-LT);

• High-protein canola meal (CM-HP); or

• Soybean meal as the sole source of amino acids and phosphorus.

Digestibility trials

The press release described how for each test ingredient, diets were formulated that contained either 0, 500, 1,500, or 2,500 phytase units (FTU) of microbial phytase, for a total of 20 diets.

Results indicated that if 0, 500, or 1,500 FTU of phytase was added, there was no difference in phosphorus digestibility among the different canola meals. However, phosphorus digestibility was less in canola meal processed at a low temperature than in the other canola meals when 2,500 FTU of phytase was added.

More P digestibility in soybean meal

Phosphorus digestibility was greater in soybean meal than in any of the canola meals when 0, 500, or 1,500 FTU of phytase was added. Prof Stein said that’s because a greater percentage of the phosphorus in canola meal is bound to phytic acid, and therefore unavailable to the pig.

In the press release he was quoted saying, “However, if more than 2,000 FTU of phytase was added to the diets, the digestibility of phosphorus in all canola meal sources except CM-LT was equal to that in soybean meal. This indicates that with sufficient phytase in the diets, the phosphorus in canola meal can be made available to pigs.”

Regression equations

Prof Stein’s team developed regression equations from the results of this experiment, which he says will make it possible to predict how much phosphorus will be released from canola meal or soybean meal for a given amount of phytase.

The paper in the Journal of Animal Science was authored by Yue She, China Agricultural University, China; Yanhong Liu and Hans Stein, University of Illinois, United States.