Soybean meal prices have been strong for nearly 2 years due to numerous factors such as pandemic fueled stockpiling, bullwhipping of supply/demand dynamics linked to asynchronous market reopenings and elevated input costs due to gross inflationary pressures. In this time, some regions have seen 100% increases in their local SBM prices - which has prompted a search for less expensive protein sources for their feeding programs. In Canada and parts of Europe, this has led to an increase in the use of canola meal products, while in the US and Brazil more corn DDGS have been used. However, as nearly all plant proteins are in some way or fashion linked to SBM base pricing, the price of canola meal, DDGS and other similar alternatives have also seen concomitant price increases as well.
As feed producers continue to search for less expensive dietary proteins, many are looking at alternatives such as whole or full fat soybeans that have been cooked, pressed or extruded in one way or the other. The advantages these ingredients have are that they are typically produced in proximity to where feed is manufactured, reducing transportation costs and in recent years have become more consistent in their nutrient composition due to advancements in the equipment used to process the raw beans. However, there is one problem that many involved have overlooked when they begin to evaluate or use non-traditional soybean ingredients and that is the presence and level of trypsin inhibitors (TI) in these products.
Trypsin inhibitors are natural anti-herbivore enzymatic compounds produced by soybeans and other legumes that, eponymously, block the production of the digestive enzyme trypsin. Trypsin, is an important enzyme for protein digestion and when not produced in sufficient quantities, undigested protein lingers in the GIT which leads to bacterial overgrowth, fermentation of undesired compounds and ultimately diarrhea. These compounds are well described and understood to be problematic when fed to livestock above certain thresholds. For example, excessive exposure to TI, in addition to reducing nutrient absorption through diarrhea generation, also reduces total plane of health thereby making animals more susceptible to enteric disease infection as well as exacerbating mycotoxicosis. So, the knock-on effects associated with TI exposure should not be ignored, as taken together, all negative outcomes will lead to reduced performance and profitability.
Historically, trypsin inhibitors have been managed in conventional soybean meal through the heating process involved in removing oil via solvent extraction, thereby deactivating trypsin inhibitors by denaturation. In non-conventional soybean products, heat applied via extrusion, toasting or pressing has been assumed to be sufficiently high and applied for a long enough duration so as to deactivate trypsin inhibitors to a non-problematic level. However, the bespoke nature by which non-conventional soybean products are produced lends itself to greater batch-to-batch variability which in turn leads to more variable levels of trypsin inhibitor levels. Combine this inherent manufacturing variability with more widespread adoption and it becomes clear that a problem, i.e. TI exposure, that for the better part of 3 decades was thought to be managed, could be something that is being overlooked and could be a factor contributing to reduced growth performance and profitability.
So what can be done to manage the risk of TI exposure that accompanies the use of non-convention soybean products? First course is to focus on detection - understanding the process by which a product is produced and implementing routine testing for each batch received is one way in which TI levels can begin to be managed. Secondly, limit exposure - setting limits within a formulation system based on batch-to-batch testing can greatly reduce the risk of over-exposing livestock to dietary TI. Lastly, treatment options can be implemented or when already in place, relied upon, whereby heat can be applied to the feed via pelleting, extrusion or expansion in order to deactivate TI from non-conventional soybean ingredients.
It is likely that the altruistic search for alternative protein sources has inadvertently led livestock to be overexposed to soybean derived trypsin inhibitors. Further, as the expertise associated with monitoring and management of TI has waned in the past decade as conventional SBM sources have become more efficient and consistent in deactivation of TI it is also likely that many feed manufacturers are either underestimating exposure or ignoring it altogether. This potential oversight could be a real world impediment to ensuring performance and health are being maximized during a market situation that requires all aspects of livestock production are being paid attention to in order to maximize profitability.