The effect of lupinosis on the nutritional value of lupins to sheep

Abstract

Lupin and non-lupin hays were fed to sheep in metabolism cages to compare their nutritive values and to assess the effects of lupinosis on food intake, digestion and metabolism. Abnormal cyclic fluctuations in voluntary food intake, sometimes ending in inappetence, occurred in all three experiments. These fluctuations in food intake were shown to be associated with lupinosis and caused considerable variability in all experimental measurements. In spite of this variability, the intake of digestible organic matter of four of the seven lupin hays was equivalent to that of the non-lupin hays. In the other three it was significantly less. The in vivo lupin hay digestibilities ranged from 52.3 to 65.0%. Rumen protozoa counts were made in one experiment and were lower in sheep receiving lupin hay containing lupinosis toxin than in those receiving a non-lupin hay, but all values were still within the biologically 'normal' range. Irrespective of the presence of lupinosis toxin, no significant differences could be established in parameters of either energy or nitrogen metabolism of sheep fed on the various hays. We conclude that hays from lupins cut at the late flowering stage have a similar nutritive value to hays made from temperate pasture species, even when there were intakes of low levels of lupinosis toxin.