Effect of extruded lupin seeds as a protein source on lactational performance of dairy cows

Twelve multiparous and eight primiparous Holstein dairy cows, averaging 70 days in milk, were used to examine the effect on feed intake and lactational performance of replacing a conventional protein supplement by extruded lupin seeds (ELS). The diets were composed of 68% forage (corn silage and alfalfa hay) and 32% concentrate on a dry matter (DM) basis. In the control diet (C), the protein supplement supplied 34% of total crude protein; in the ELS diet, lupins provided 40% of total crude protein. Cows were fed twice daily during the experimental period (14 weeks). Total dry matter intake (DMI) was lower (P<0.05) with the inclusion of ELS (21.3 vs. 21.6 kg day−1). The ELS diet increased milk yield (36.0 vs. 32.6 kg day−1) and lowered milk protein (2.80 vs. 3.00%). Milk fat content and yields of fat and protein were not affected by the treatment. Daily body weight (BW) gain averaged 0.55 kg for the ELS diet which was not different from the 0.45 kg for the C diet.