For many New Zealand dairy farms, protein is most likely to be production limiting during the summer months. Pasture protein levels of dry, stalky ryegrass pasture can be as low as 10-12%, which is considerably lower than the 14-16% requirement of late to mid lactation dairy cows.

Farmers who rely on high volumes of low protein feed supplement, such as maize silage, cereal silage or grains, to fill summer feed deficits or meet the early lactation requirements of autumn calving herds may also experience protein deficiencies and should consider feeding Lucerne hay.

Research (Macdonald et al, 1998) shows that including 0.7kg pf protein in a 50:50 diet of maize silage and summer/autumn pasture increased the protein content of the diet from 11.8-16.8%. Milk solids production increased by115-165gMS/cow/day for soybean and fishmeal respectively.