Abstract: The present disclosure provides methods and compositions for the following: improving rumen fermentation efficiency; increasing the efficiency with which dietary starch is utilized while preventing a deleterious increase in ruminal lactic acid concentration and/or a deleterious drop in ruminal pH; and promoting the growth of beneficial ruminal microorganisms. As a result, there is a concurrent improvement in the productivity and profitability of ruminant animal husbandry, especially in the diary and beef industries. These methods and compositions provide for the supplementation of the diet of a ruminant animal with exogenous amylase at relatively low levels, without any concomitant need for exogenous fibrolytic enzymes such as cellulases and xylanases. The methods and compositions of the present invention can further comprise supplementation with yeast preparations, rumen buffering agents, ionophores or other growth and productivity stimulating agents.