SummaryDuring 3 years, three groups of 20 Scottish half-bred ewes were grazed on perennial ryegrass, white clover or red clover. During this period the two legumes were oestrogenic, in terms of teat-length extension of wethers, but the perennial ryegrass was not. The white clover was only markedly oestrogenic when there was a high proportion of diseased leaves. The mean litter size and lambing percentage of the ewes grazed on red clover was significantly reduced. White clover, although it was oestrogenic, had no effect on mean litter size or lambing percentage. The mean litter size of the ewes on the perennial ryegrass was 2·35, 2·30 and 2·24, on the white clover was 2·20, 2·33 and 2·23 and on the red clover was 1middot;60, 1·67 and 1·78 for the three lambings. Lambing percentage of the ewes on the perennial ryegrass was 175, 225 and 218, on the white clover was 210, 222 and 189, and on the red clover was 160, 128 and 118 for the three lambings. The lambing date of the ewes grazing on the red clover was significantly later at the third lambing.
SUMMARYOestrogenic activity was recorded by teat length extension in wether lambs grazing red clover S. 123 in September and October 1965 and between 21 April and the end of October 1966. The number of lambs born alive to ewes grazing red clover (S. 123) for the 2 weeks prior to mating and for 4 weeks after mating was reduced. Oestrogenic activity was also recorded in wether lambs on lucerne var. Eynsford and on white clover S. 100 from mid-June to mid-October 1966.Oestrogenic activity was confirmed in red clover, but not in lucerne, by mouse bioassay. Slight oestrogenic activity was shown in one white clover sample only.
SUMMARYThe oestrogenic activity and coumestrol content of ‘diseased’ and ‘clean’ white clover and lucerne were investigated. It was found that both coumestrol content and oestrogenic activity were increased in diseased white clover. However, there was insufficient coumestrol to account for the oestrogenic activity and it was suggested that other factors (e. g. oestrogen potentiator, unidentified oestrogen) were involved.
Masham ewes were mated at three stages of the breeding season, early (15 September to 20 October), mid (20 October to 24 November) and late (15 December to 19 January), at two different body condition scores, 4 and 2, for 3 successive years. The mean scores achieved for body condition 4 were 3-6, 3-7 and 3-9 for early, mid and late respectively and for body condition 2 were 2-4, 2-3 and 2-2. In the late lambing flock more ewes were marked by vasectomized rams and less ewes were barren than in the early and mid flocks. The ewes in higher body condition at mating had significantly more triplets and fewer singles, and a higher lambing percentage (183 versus 165). This effect of body condition on litter size distribution was significant at each time of mating, with the ewes at the late mating producing significantly fewer triplets and more singles; this difference was caused by a reduction in the performance of the body condition 4 ewes in the late group. Young ewes in the body condition 4 group produced significantly fewer triplets and more singles than the mature ewes in the same body condition group, but at the lower body condition age had no effect on litter size distribution.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.