Use of Ionophores in Grazing Ruminants

Abstract

The use of ionophores in ruminant diets is one of the success stories of application of technology to livestock production. They have been fed for more than 20 years with positive and repeatable responses across a wide range of production systems. Ionophores are antibiotics that affect certain bacteria, protozoa and fungi in the rumen. Three polyether ionophores (ionophores with carboxylic terminal groups) available for ruminants today are monensin (Rumensin ®), lasalocid (Bovatec®) and laidlomycin (Cattlyst®). When added to the diet per manufacturer's recommendations, they change the profile of fermentation products and the degradation of dietary protein in the rumen, thereby improving the efficiency of nutrient use by ruminants. The fermentative processes that are affected by ionophores - production of ammonia and volatile fatty acids (VFA) in the rumen - are key processes because they affect directly nitrogen and energy metabolism in the host ruminant. This review will emphasize the results of studies with grazing cattle, with data and information from other reviews^30,48,62,65 as well as data from recent publications.