LUPIN (LUPINUS-ANGUSTIFOLIUS), COWPEA (VIGNA-UNGUICULATA) AND NAVY BEAN (PHASEOLUS-VULGARIS) SEEDS AS SUPPLEMENTS FOR SHEEP FED LOW-QUALITYROUGHAGE

Three experiments compared the nutritive value of whole unprocessed se eds of lupins (Lupinus angustifolius cultivar 'Uniharvest'), cowpeas ( Vigna unguiculata cultivar 'Caloona') and navy beans (Phaseolus vulgar is cultivar 'Actolac') as supplements for young sheep fed low quality roughage ad libitum. In Experiment 1, a 49 day feeding trial, three le vels (10, 20 and 40 g kg(-1) W-0.75) of lupin supplement progressively increased total dry matter (DM) intake, liveweight (LW) gain and wool growth, but roughage intake was decreased by 19% and 48% when 20 and 40 g kg(-1) W-0.75 respectively were fed. When cowpea supplement was f ed, responses as feed intake and LW gain were similar to those observe d for lupin supplement. Wool growth was increased by 10 and 20 g kg(-1 ) W-0.75 cowpeas, but was not further increased by 40 g kg(-1) W-0.75. A low level (10 g kg(-1) W-0.75) of navy bean supplement resulted in similar intake and productivity responses to those observed with the s ame level of lupins or cowpeas. However, when higher levels (20 and 40 g kg(-1) W-0.75) of navy beans were offered, although total intake in creased, LW gain and feed conversion efficiency (FCE) were lower than for equivalent levels of lupins or cowpeas, Also sheep offered 40 g kg (-1) W-0.75 of navy bean consumed only 82% of the supplement, and wool growth was lower than for the equivalent level of lupins. Addition of a mixture of terramycin and flavomycin antibiotics to the lupin suppl ement fed at 40 g kg(-1) W-0.75 increased LW gain, but did not affect FCE or wool growth. Antibiotic addition to navy beans had no effect on performance. In Experiment 220 g kg(-1) W-0.75 of each of the legume seeds was fed as a supplement for roughage, Total intake and organic m atter digestibility were similar for the three supplements and greater than when no supplement was fed. However, the concentration of nitrog en in faeces was higher when cowpea or navy bean rather than lupin sup plement was fed. In Experiment 3 when rumen cannulated sheep were supp lemented with each of the legume seeds, DM, lectin activity and trypsi n inhibitor activity rapidly disappeared from synthetic fibre bags con taining ground legume seeds and incubated in the rumen, suggesting rap id and extensive fermentation or solubilization of these components. I t was concluded that lupin and cowpea supplements resulted in similar intake and growth responses in these young sheep fed low quality rough age. However, reduced wool growth when a high level (40 g kg(-1) W-0.7 5) of cowpeas was fed suggested that protease inhibitors in this grain legume reduced amino acid availability to the sheep. A low level (10 g kg(-1) W-0.75) Of navy bean was satisfactory as a supplement, but wh en moderate or high levels (20 or 40 g kg-L W-0.75) were used LW gain and wool growth were lower than expected, presumably due to detrimenta l effects of antinutritional factors in the navy beans which were not inactivated by rumen fermentation.