Feed is expensive — especially the grains that serve as the major energy source in most finishing rations for beef cattle. With this expense on the rise, nutritionists work hard to make sure that their feedlot rations for beef cattle are high-quality feeds that support weight gain and feed conversion efficiency.
Energy is a key element to consider when developing a feed to promote weight gain in beef cattle. Both grains and forages contain energy that is useful when finishing beef cattle. Grains are considered high-energy feeds because the energy in grains comes largely from starch. Starch is composed of glucose chains, which can easily be broken down by rumen microorganisms. The structural components of forage — such as cellulose, hemicellulose and lignin — surround the nutrients with complex linkages. Rumen microbes can’t always break these linkages, however, limiting the availability of energy in the forage. This is particularly true for feedlot cattle, as the ruminal pH of feedlot cattle is less than optimal for fibrolytic microorganisms, resulting in reduced fiber digestion.
When thinking of these structural components, imagine them as locks protecting the energy and nutrients in feedstuffs. Enzymes — which are either endogenous, from the microbial population, or the exogenous enzymes in feed additives — can break apart these protective structural components, unlocking both the potential of feeds and the potential of the cattle being fed.
Enzymes can make a difference in finishing cattle.
The scientific literature shows inconsistent results for enzyme use in beef cattle diets. However, this is likely due to the wide variety of enzymes that have been tested, the vast array of feedstuffs that have been used in experimental diets, and the kind of data that has been recorded. For example, cattle grazing cool-season versus tropical grasses have different enzymatic needs, because those grasses have different chemical compositions. The same goes for cattle consuming corn silage versus barley-based finishing diets. This is especially true in diets that utilize byproducts, as the most easily accessible nutrients have generally already been extracted by the initial industry that processed the material.
• Starch-based diets: Corn, barley
• Forage-based diets: Corn silage, barley silage, hay and grasses
• Byproducts in diets: Corn gluten meal, distillers grains, cottonseed hulls, etc.
The rumen is a complex, enzyme-rich environment. The microbes of the rumen can break down most components of foods — but the extent and speed of this breakdown is often a limiting factor for nutrient release. A common question when discussing rumen efficiency is: Can a small enzyme addition really make a change in rumen function and feed digestion?
For an enzyme to be effective, several factors need to be met:
• It must fill a gap in feed digestion not met by the existing microbiota.
• The type of linkage it opens must be present in the feed.
• The enzyme needs to be stable in stored and mixed feed.
• The enzyme must be active at rumen temperature and pH.
• It must be able to survive in the feed. Returning to the lock-and-key metaphor about enzymes, any enzyme added to a diet must fit the “locks” on the components of that diet.
How do you measure enzyme efficacy in finishing cattle?
Measuring the effects and value of enzymes can be tricky. Often, researchers expect an increase in the rate or extent of digestion for a particular diet component — and sometimes, they are right. Other times, however, the enzyme acts in an unanticipated way, such as changing the rate of passage to promote feed intake, shifting the metabolites available to microbes in the rumen, or even affecting downstream metabolic processes. If researchers are not measuring these actions, they may conclude that the enzyme had no effect, when in reality, they were simply looking in the wrong direction and missed the action of the enzyme. As such, in enzyme research, it is important to look beyond intake, weight gain and feed conversion and to measure a wide range of parameters to fully capture the effects and mechanisms of a given enzyme.
Outside of the scientific realm, it’s important to recognize what you expect an enzyme to do when it is added to the diet. Here are a few common reasons for utilizing enzymes:
• By incorporating enzymes into your finishing rations for beef cattle, you may be able to utilize lower-cost ingredients in the diet while still experiencing equal performance.
• Enzymes can help improve feed efficiency in feedlot cattle without making any other changes to the diet.
• Getting more pounds on your animals can be possible with enzymes. Certain enzymes can support superior carcass weight. More pounds per day = more dollars.
• Some enzymes reduce digesta viscosity, which can contribute to better post-ruminal nutrient absorption and support digestive health. Get the most out of your rations.
Look at your cattle’s diet and your goals for your operation. Could enzymes help you reach those goals?
There are enzyme options available — just know your goals
Most research on cattle focuses on tweaking existing procedures, feeding plans, etc. Researching enzymes takes years of trial and error, on both the benchtop and in the animal, to find effective, cost-efficient, scalable options. This type of research is slow but generates the knowledge that can lead to new insights and technologies that allow us to maximize feed efficiency in feedlot cattle. New enzymes are popping up regularly. If you choose to utilize these additives in your feedlot rations, be sure that they are effective on the ration ingredients you use and will provide the results you want in your operation. Consult with your nutritionist to learn more about how enzymes can work in your operation.