Lupin as a protein supplement for growing lambs

Whole lupins (Lupinus albus) were roasted with exit temperatures ranging from approximately 130 (moderate heat) to 175 degrees C (high heat). In situ N disappearance after 12 h of incubation in the rumen was 83% for raw lupins, 45% for lupins roasted at moderate temperatures, and 39% for lupins roasted at high temperatures. Lambs fed lupins roasted at moderate temperatures retained more N (P < 0.01) than those fed soybean meal (SBM). However, growth rate and feed efficiency were similar among lambs fed diets containing SBM raw lupins, or roasted lupins. Dehulled lupins commercially roasted at low, moderate, and high temperatures resulted in ruminal in situ N disappearances of 59, 47, and 43% for the respective temperatures. Dehulled lupins (Lupinus albus) were also roasted in a laboratory oven for 2, 4, and 6 h at 120, 140, and 160 degrees C. Simulation of roasting for 2 h had no effect (P > 0.10) on ruminal in situ N disappearance at any of the temperatures. In situ N disappearance was reduced (P < 0.05) after roasting for 4 h at 160 degrees C, but acid detergent insoluble N was only moderately increased. Nitrogen retention in lambs fed raw, dehulled lupins was equal (P > 0.10) to that of lambs fed SBM. Whole lupins or dehulled lupins can replace SBM as the sole protein supplement for growing lambs. Although roasting lupins decreased ruminal in situ N disappearance, it had no effect on growth of lambs.