Bioassay responses of ewes to legume swards. II. Uterine weight results from swards

Abstract

Three years' results of sheep uterine weight bioassays on a range of clover swards are presented. Trifolium pratense L. (var. Grasslands Hamua Broad) and Trifolium subterraneum L. (var. Dinninup, Dwalganup, Tallarook, and Yarloop) showed high activity whenever they were green. Trifolium fragiferum L. (mixed+Palestine), Trifolium repens L. (var. Victorian Irrigation), and Trifolium subterraneum L. (var. Bacchus Marsh, Howard, Marrar, and a breeder's selection) showed variable activity; Medicago sativa L. (var. Hunter River), Medicago littoralis (Rhode), Trifolium alexandrinum L., Trifolium incarnatum L. (var. Dixie), and Trifolium repens L. (var. Grasslands Huia and Ladino) have not shown activity. Spraying two of the clovers with paraquat and dosing the sheep with cobalt sulphate had no effect on activity. There was a strong seasonal trend with highest activity in midwinter and lowest in mid spring. The relationships between chemical assay and bioassay results are discussed. There is reasonable evidence that the activity of Victorian Irrigation white clover is not related to any of the compounds being measured.