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New Insights on the Urease Activity Range for Soybean Meal

Cells of a Raw Soybean

In our years of optimizing the quality of extruded whole soybeans and the ExPress® soybean meal, we have been insisting on cooking the soy to a range of 0.02-0.06 PH. Rise or Urease activity. We have faced objection after objection from consultants and nutritionists suggesting that we may be over-cooking the soybeans.

The fact was, and still is, that this recommended range of Urease activity was based on the optimum nutrient digestibility we observed at extrusion temperatures that will give us this range of Urease activity.

The “acceptable” range in the industry has been from 0.1-0.2 and sometimes, 0.3 PH rise since this is what they can find in the literature.  To us, at those ranges, the soybeans or the soybean meal are definitely undercooked.

Dr. Nelson Ruiz presented evidence at the 2012 Arkansas Poultry Federation Nutrition Conference that supports what we have been recommending since the early 1990’s regarding the acceptable range of Urease activity.

Dr. Ruiz stated the following:

1- Since 2005, it has been reported that high Trypsin inhibitors in soybean meal (over 3.5 mg/gram) are correlated to rapid feed passage outbreaks in broilers. It is a condition in which broiler droppings lose their normal shape and consistency and contains undigested feed visible to the naked eye.

2- Data accumulated over 8 years from a large number of rapid feed passage events in the poultry industry supported the concept that optimum residual trypsin inhibitors in commercial soybean meal is below 2.0 mg/gram. This correlates to a Urease activity of 0.06 PH rise.

One asks how did the poultry industry get by with higher trypsin inhibitors in the last 50 years while now it is having problems?

The fact, as Dr. Ruiz explains, is that the broilers that are used today consume enormous quantities of feed to express their genetic potential as compared to decades ago and subsequently, the upper limit of Urease activity was valid then but not now. Higher consumption of urease and subsequently, trypsin inhibitors due to higher feed intake will result in rapid feed passage and ultimately, inferior performance.

Dr. Ruiz’s recommendation for Urease activity in properly processed soybean meal is 0.00- 0.05 PH. Rise.

It is not far from our recommendation of 0.02-0.06 PH. Rise.

The takeaway is this, the best way of optimizing the soybean process is to trust the animals that are consuming it.

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