The potential of two rough-seeded lupin species (Lupinus pilosus and L. atlanticus) as supplementary feed for sheep

Abstract

The rough-seeded lupins are better adapted to alkaline soils than the domesticated lupins currently in use in commercial agriculture in southern Australia. Lupinus pilosus and L. atlanticus are two species of rough-seeded lupins that are undergoing domestication, and could be very valuable for sheep as a supplementary feed. However, there is little information on the nutritive value of these lupins. Two experiments were conducted to evaluate the nutritive value of L. pilosus and L. atlanticus, compared with L. angustifolius, which is widely used as an animal feed in Australia. The results showed that the rough-seeded lupins examined had larger seeds, a greater proportion of seed coat in the whole seed, and a higher fibre content in the seed coat than domesticated lupins. Nitrogen (N) content in the kernel of the various lupin species was similar. The high fibre content in seed coat did not appear to limit the digestion of the seeds by sheep as demonstrated by the high potential degradability of seed dry matter (DM) for all lupin species. There were no significant differences betweenL. pilosus,L. atlanticus, andL. angustifolius as a supplementary feed provided at low levels in DM digestibility (DMD), apparent energy digestibility (AED), and N-balance, suggesting that L. pilosus and L. atlanticus could be used in place of L. angustifolius. AlsoL. atlanticus could be substituted for L. angustifolius at high levels of supplementation as there were no differences in DMD, AED, apparent N digestibility, and N-balance when these species were fed to sheep as a supplement to barley straw. Supplementation with lupin seed at 150 g/day significantly improved DM intake by 195 g/day, DMD by 8.7, and AED by 11.4 percentage units. However, a high level of lupin supplementation in a diet based on barley straw did not increase DMD and AED of the diet.