HOW LIVE YEASTS USED AS DFMs CAN IMPROVE FEED EFFICIENCY IN RUMINANTS : THE RUMEN MICROBIOTA AS A CRUCIAL TARGET

摘要

In order to answer to the increasing demand for safe and of good nutritional quality products of ruminant origin, and in the context of increasing feed costs and of sustainability concerns of agricultural systems, improving animal feed efficiency hasbecome a critical need for cattle farmers.Rumen function optimization appears to be a crucial target to improve animal efficiency. Indeed, this digestive compartment hosts a complex anaerobic microbiota responsible for degradation and fermentation of the main part of dietary components ingestedby the animal. However, many factors can impair rumen function. In this context, direct fed microbials (DFMs), such as live yeasts are an important tool to improve feed efficiency and performance and at the same time to prevent health disorders (Chaucheyras-Durand et al., 2008; 2012). Yeasts benefit from a natural and well-accepted image by the consumer, as they are not involved in health disorders and do not have any detrimental impact on the environment. Recent multi-study analyses performed both in dairy and beef cattle have shown significant benefits with Saccharomyces cerevisiae 1-1077 on yield and feed efficiency (Erasmus et al., 2009; De Ondarza et al., 2010). This paper addresses the last findings in terms of mechanisms of action of live yeasts on rumen microbiota, with a focus on pH stabilisation effect, improvement in plant cell wall degrading communities, and on consequences on rumen efficiency, animal productivity and health.