According to their etymology, antimicrobials are substances against the life of microorganisms. (The word “antimicrobial” comes from the Greek “anti” [which means “against”], “mikros” [meaning “small”], and “bios” [which means “life”]).
The most recent nitrogenous formulation systems for dairy cows are based on the concepts of digestible protein in the intestine and the contribution of amino acids to the small intestine of ruminants
Lactating cows at peak lactation can require up to 18% crude protein on a dry matter (DM) basis in their diet. The protein portion of a diet accounts for the largest cost in a lactating cow’s ration.
Numerous methodologies have been designed to increase the amount of a nutrient that passes through the rumen without degradation by the rumen microorganisms, thereby resulting in the delivery of a larger portion of that nutrient to the lower gastrointestinal tract.
Much research has concentrated on the effects of starch on the rumen microbial population (both positive and negative). Recent research3 however, showed that the fiber to starch ratio in the diet, also affected the growth of the rumen papillae in lactating dairy cows.