Feed accounts for over 75 per cent of the variable costs in beef production systems. Any improvement in feed conversion efficiency will therefore have a beneficial effect on enterprise profitability. Growth promoters are commonly used to improve animal performance by increasing liveweight gain and/or improving feed conversion efficiency. With the recent ban on hormone implants in EEC countries, more emphasis has been put on the use of feed additives to improve performance.

Producer experience would suggest that the routine inclusion of sodium bicarbonate into barley beef rations can show beneficial responses in terms of animal performance. The magnitude of these responses is not well quantified, nor is the potential interaction between sodium bicarbonate and other feed additives.

Rogers and Davis (1982) reported that sodium bicarbonate decreases the in vivo production rate of propionate, decreases retention time of liquids and alters digestibility of nutrients. Increasing ruminal bypass of nutrients may improve utilisation by altering the site of digestion with a subsequent improvement in animal performance. Rogers and Davis (1982) also described the effect of monensin; which increased in vivo ruminal production of propionate, increased ruminal retention time of solids and liquids and improved digestibility of nutrients.