One of the primary goals when feeding cows is to maximize fiber and starch digestibility for efficient production. Recent data out of Rock River Laboratory, however, suggests that most cows have room for improvement. As observed in Figures 1 and 2, most high-performing cows in U.S. dairy herds are below the recommended 42% total tract NDF digestibility and 97% total tract starch digestibility goals.
It is estimated that just a 1% increase in total tract digestibility can lead to an additional 0.74 lb. and 0.84 lb. of milk for NDF and starch, respectively. Given that small improvements in total tract digestibility can have a big impact on cow productivity, it makes sense to look for ways to optimize feed utilization.
Another tool in the toolbelt
Cows rely on rumen microbes and digestive enzymes to break down feed throughout the digestive tract. A variety of methods can be used to improve the cow’s ability to digest feedstuffs such as altering feed quality, frequency of feeding, diet nutrient profile or TMR chop length. Functional additives like exogenous enzymes can also be a useful tool for improving feed utilization.
Exogenous enzymes are enzymes produced by fungi or bacteria and fed to livestock. More than 25 exogenous enzymes are currently approved for use in livestock, with common ones used in dairy cows being amylase, hemicellulase and cellulase.
Enzymes are believed to work in two primary ways. First, they can physically break down feed, allowing for improved access by rumen microbes and digestive secretions. Second, they can enhance rumen microbial attachment to the feed and support rumen microbial enzyme secretion, making rumen microbes more effective at breaking down feed. The net effect is improved total tract fiber, starch and protein digestibility.
Increasing efficiency with exogenous enzymes
Exogenous enzymes tend to be most effective in breaking down moderate-quality feeds and in energy-limited, high-producing, early lactation cows. Additionally, enzymes tend to perform best when paired with other rumen-modifying functional additives like yeast-based products or probiotics, as they work synergistically to create an optimal environment for rumen microbial activity.
The impact an enzyme will have on total tract digestibility will depend on the herd’s starting point. Those with a lower starting total tract digestibility tend to see greater improvements. For example, a herd with 94% might expect to improve to 97% total tract starch digestibility with the use of a quality enzyme. On the other hand, a herd starting at 98% might only improve to 98.5% total tract starch digestibility.
Is an enzyme right for your herd?
When choosing to put an enzyme in your herd’s diet, consider three things.
First, does the enzyme have quality data showing it is efficacious in dairy feedstuffs? Second, what is your herd’s starting total tract digestibility and is there enough room for improvement? And finally, are your feeds in the moderate-quality range where enzymes can be most beneficial?
If you can answer yes to all three questions, it’s time to speak with your nutritionist. Enzymes may be a useful tool for supporting improved feed utilization in your herd.
