A compound feed that is designed to be given in equal amounts with cereals for milk production would contain about 30% crude protein, and if rapeseed meal were the major high protein supplement to be used along with cereal, about 60% would need to be included. No observations have been reported in which this high proportion of rapeseed meal has been used and the experiment described was planned to provide this information, using low glucosinolate rapeseed meal. The control diet contained soyabean meal in place of rapeseed meal, and a third compound was used containing sunflower meal seed as the major protein supplement.

Thirty-nine Friesian cattle were used in a randomised block design: the three treatments, compounds containing low glucosinolate rapeseed meal, sunflower seed meal and soyabean meal, were applied for 16 weeks. There were 21 cows and 18 heifers, the mean days in milk at the start of the experiment was 62 days and the mean yield over the previous two weeks was 26.9 kg.