Certain Lathyrus species have recently been found suitable as multipurpose legume crops in the southern Australian dryland regions, with a potential growing area of 100,000-300,000 ha. However, their use is limited by the presence, mainly in seeds, of 3-(-N-oxalyl)-L-2,3-diamino propionic acid (ODAP), an agent which causes lathyrism. Researchers at the Centre for Legumes in Mediterranean Agriculture (CLIMA) have selected a high yielding variety of Lathyrus cicera (cv. Chalus) which contains consistently low levels of ODAP. The aim of the present study was to assess the nutritional value and animal health aspects of L. cicera cv. Chalus grain as a feed for sheep. Comparisons were made against lupin grain (Lupinus angustifolius).Eighty individually penned Merino wethers (35+/-0.3 kg) were allocated to four treatment groups of 20 sheep, Following a 4-week adjustment period, sheep were fed ad libitum the following treatment diets for up to 13 weeks: 35% lathyrus, 35% lupin, 70% lathyrus and 70% lupin. The remainder of the diet was oaten hay and minerals. After 10 weeks on treatments, 14 sheep per group were killed for carcass assessment. The remaining six sheep were fed to maintenance ME requirements for I week followed by a 10-day faecal and urinary collection period.Analysis of the grains showed that lathyrus contained less protein (28% versus 36%), fat (0.7 versus 4.1%) and fibre (25% versus 36% NDF), but more starch (42% versus 1%) and anti-nutritional compounds (ODAP, tannins, trypsin inhibitor) than lupin. Essential amino acid composition was similar for the two grains, as were in sacco degradabilities of dry matter (DM) (84% versus 81%) and protein (92% versus 94%).The feeding experiment showed that lathyrus had a higher nutritional value than lupin in terms of voluntary feed intake, liveweight gain (P <0.01), carcass weights (P <0.05) and feed efficiency (P = 0.05). Wool growth reflected ME intake, and there was no independent effect of grain type (P > 0.05).Results from the balance study showed that ME concentration was the same for both grains (14 MJ/kg DM). Microbial crude protein (CP) synthesis, estimated from urinary purine derivatives, was significantly lower for lathyrus than lupin, and was lower at 70% grain inclusion than at 35% (P <0.05).There were no visible or biochemical signs of ill health (in-appetence, lethargy, shaking or instability) in any sheep fed lathyrus. Several sheep fed the 70% lupin diet had mild diarrhoea, and two were eventually removed from the experiment due to anorexia.Meat from sheep fed lupin tended to be yellower than that from those fed lathyrus (P = 0.05). Apart from this, there were no differences in meat quality due to grain type (e.g. redness, pH, taste or tenderness).In conclusion, compared with lupin grain, low ODAP L cicera grain appears to be of high nutritional value for sheep, with no evidence of adverse effects on sheep health. (C) 2002 Elsevier Science B.V. All tights reserved.