Three experiments were conducted to determine optimal substitution of
lupin for soybean meal in dairy cattle diets; the effects of whole ver
sus ground lupins and the effects of whole lupins versus whole soybean
s on milk production were examined. In the first experiment, 57 cows w
ere assigned randomly to treatments in blocks of five by calving order
within parity. Treatments began 22 d postpartum and continued through
d 140. Diets were isonitrogenously balanced using soybean meal as con
trol: lupins replaced 0, 25, 50, 75, and 100% of supplemental protein.
Cows that consumed 75% of supplemental protein as lupins produced mor
e 3.5% FCM and fat than cows that consumed the control diet. In a seco
nd experiment, 30 primiparous cows were assigned randomly by calving o
rder to either ground or whole lupins (60% of supplemental protein). T
reatments began 32 +/- 3 d after calving and lasted for 84 d. Cows tha
t consumed ground lupins produced more milk and 3.5% FCM than cows tha
t consumed whole lupins. In the third experiment of 84 d, 28 primiparo
us midlactation cows were assigned randomly to diets containing whole
lupins or whole soybeans to supply 1 kg of supplemental protein. Cows
fed whole lupins produced milk with higher fat content, more 3.5% FCM,
and more fat than cows consuming whole soybeans. Lupins are an accept
able supplemental protein source for dairy cows.