Results from three previous experiments with finishing cattle on an 18-month beef system indicate that the major increases in daily live-weight gain (DLG) occur within the first 50 to 60 days of supplementation with fish meal. Hence, it may be possible to remove fish meal from the diet after the initial two months of the finishing winter without any subsequent effect on animal performance.

For the last nine weeks at grass the experimental cattle were given 1.4-kg/head/day dried sugar beet pulp nuts. On housing this allowance was increased to 3.0 kg and the 48 British Friesian steers were offered grass silage ad libitum (round bale silage for one week and precision-chopped clamp silage thereafter). The 3.0-kg dried sugar beet pulp was given for five days and after a 10-day changeover period the nuts were replaced by 15-kg potatoes. Cattle were offered the basal diet of precision-chopped silage and potatoes for 12 days before starting the experiment.

Steers were implanted with 300-mg trenbolone acetate (Finaplix, Hoechst UK Ltd, Milton Keynes) and 36-mg zeranol (Ralgro, Crown Chemical Company Ltd, Lamberhurst) 20 days before randomisation.