The introduction of the Single Farm Payment support system sees a change from headage to area payments. The removal of the Beef Special Premium for steers is likely to see a move towards either 12-15 month intensive finishing systems or low input extensive grass based 24-30 month finishing systems. Late maturing breed type cattle reared on the latter system may however require a 2-3 month intensive finishing period to achieve adequate fat cover. With falling cereal prices there is increased interest in their use in beef cattle rations. Antibiotic based feed additives e.g., monensin sodium, have been successfully used for over 40 years to manipulate microbial activity and improve beef cattle performance. The use of monensin sodium will be banned from January 2006 and there is therefore a requirement to find alternative ‘natural’ products that can improve the efficiency of beef production with intensive cereal based rations. Yeast cultures are composed of yeast (Saccharomyces cerevisiae ) and the medium on which it was grown. These products are dried in a manner which preserves the fermenting activity of the yeast. It is suggested that production responses associated with the use of live yeast culture supplements in ruminants may be related to their stimulatory effects on specific groups of micro-organisms in the rumen. The objective of this study was to determine the effect of feeding a live yeast culture (Yea-Sacc1026) on the performance of cereal fed beef cattle.