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Good Clover, Bad Clover

Wednesday, May 24, 2017

The Mackillop Farm Management Group (MFMG) and AgKI with support from MLA and SheepConnect SA are undertaking a project (‘Good clover, bad clover’) which will focus on upskilling producers on oestrogenic clover identification and the implementation of practices to improve lamb marking rates. The first part of the project is a survey of producers to get an indication of the extent of oestrogenic clovers, potential impacts on fertility and producer knowledge about the issue.

MFMG is keen to get feedback from producers across the State that have clover pastures. Please complete the survey on-line via Survey Monkey. The link is http://www.surveymonkey.com/r/Good_clover_Bad_Clover

Oestrogenic clovers were a major cause of sheep infertility back in the 1950’s and 60’s. Lambing percentages below 30% were often experienced in some areas of SA. With the development of low oestrogenic clover varieties and grazing
management strategies the issues experienced were generally overcome. However, recent evidence suggests that significant levels of the old oestrogenic varieties have built up in some pastures and this may be impacting on ewe fertility.

Infertility in sheep grazing on pastures dominated by oestrogenic legume cultivars is associated with the breakdown of sperm transport in the uterus. Temporary infertility occurs when ewes are mated on green oestrogenic clover. The reduction in fertility recovers to normal levels within a few weeks of removal from the pasture. Permanent infertility (’clover disease’) however may occur when the ewes graze such pastures for extended periods, leading to permanent changes in the reproductive tract. Cysts form in the uterus and cervix and the uterus does not contract normally at parturition. Dystocia and other reproductive problems may be observed.

Cultivars of subterranean clover that contain high oestrogen concentrations include Yarloop, Dwalganup, Dinninup, Geraldton and Tallarook. Woogenellup, Seaton Park and Clare have also shown slight oestrogen activity in ewes.

In the high-oestrogen cultivars of subterranean clover, oestrogen concentration is increased by nutrient deficiency (low phosphorus and low sulphur), by disease, waterlogging and drought or moisture stress.

For further details on the project contact Tiffany Bennett on 0488 524 609 or Ian McFarland on 0437 659 353.