Substituting a small proportion of barley with white fish meal has been shown to increase the daily gain cattle grown through the winter using diets based on grass silage. The object of this work was to determine iether offering fish meal during winter affected the performance of the animals at grass. The trial was made 7 farms and involved 280 cattle. They varied in live weight at the start of the trial from 140 to 370 kg. each farm there were two groups of cattle, one group was given barley and for the other group 0.25 kg/d rley was replaced by white fish meal. The cattle were weighed at the start of the trial after 90, 160 urnout) 220 and 300 days. The two latter weighings were made while the cattle were at grass.