NUTRITIVE-VALUE OF RAW AND ROASTED SWEET WHITE LUPINS (LUPINUS-ALBUS)FOR LACTATING DAIRY-COWS

Nine multiparous cows in early lactation were fed alfalfa silage ad li bitum twice daily, a grain-based concentrate five times daily, and one of three protein sources five times daily. Supplemental proteins were soya-bean meal, raw coarse-ground sweet white lupins or roasted coars e-ground sweet white lupins. Roasting of lupins increased the calculat ed undegraded intake protein (UIP) proportion from 7.2 to 33.3% of tot al nitrogen. Intake of dry matter and organic matter was lower for lup in-supplemented cows, but intake of neutral detergent fibre was simila r for all cows. Production of milk, and milk components, was similar a mong treatments although milk protein concentration was lower, and mil k protein yield tended to be lower, for lupin-supplemented cows. Cows on all diets used dietary protein much more efficiently than calculati ons based upon National Research Council recommendations would suggest . Although lupin oil only comprised 1.1-1.2% of dry matter intake, cha nges in milk composition were typical of those associated with fat fee ding as de novo synthesis of C-10 to C-16 fatty acids was suppressed, transfer of long-chain fatty acids was increased and protein percentag e was decreased in milk from lupin-supplemented cows. Roasting appeare d to increase protection of lupin oil from ruminal hydrogenation, as e videnced by increased concentrations of long-chain fatty acids in milk from cows supplemented with roasted lupins. The changes in fat compos ition are positive for the public perception of a more hypocholesterol emic milk fat, but the decrease in protein percentage is a concern bot h for the manufacture of milk products and with respect to changes in milk pricing formulae that assign a higher value to milk protein than to milk fat.