Adding fiber-degrading enzymes to the diet of dairy cows has been explored for quite some time. These exogenous enzymes allow for a greater digestibility of the roughage which results in more nutrients available for production. Recent publications have shown that the range of increased milk production has been between 0.20 and 3.6 kg/day however, the results have been inconsistent.
The main reason for this variability is that there are multiple factors that influence the response. Examples are differences in enzymatic activity, dosage, days in milk, time of delivery, ruminal microbial population, enzyme stability and specificity of the enzyme to the type of fiber in the diet.
As could be expected, the ration composition and particularly the forage/concentrate ratio, bear also significance on the degree of response to these enzymes. Diets that consist of a larger proportion of forage (50% and above) will obviously elicit a greater response provided the type of fiber and the enzyme added have an acceptable degree of compatibility. It is thus critical to test which are those conditions that optimize the fiber-degrading effects of these enzymes.