We were recently contacted by a Vet because he had visited a property where Romney ewe hoggets had been grazing lucerne since January 4th til APRIL 4th. At this time the hoggets were showing signs of udder development which is a clear indication of a highly oestrogenic crop. In our experience young stock such as hoggets are more susceptible than mixed age ewes but this remains to be confirmed experimentally. Recent work at LU has shown removing stock from lucerne two weeks before mating is sufficient to minimize any impacts on ovulation. These hoggets were due to go to the ram in May so they are growing well on lucerne but will be removed from the lucerne 3-4 weeks prior to this. For further information on recent LU results related to oestrogens in lucerne and red clover see the links provided at the end of this post.
These photos show the stage of teat and udder development and th fresh healthy looking lucerne they were grazing. Make sure you are aware of this issue and how to minimize impacts by signing up to the BLNZ txt service which sent out several warnings about this issue in response to the wet autumn many regions experienced.
Of note – the Vet also noted udder development in other ewe hoggets which were grazing on red clover/plantain in the same property. The compounds causing this differ between the lucerne (coumesterol) and red clover (formononetin) and there is little recent data related to managing the phenomenon in red clover. We suggest a similar strategy to that recommended for lucerne as a starting point.
To subscribe to the lucerne text messaging service:
To join this service email email@example.com or call 0800 BEEFLAMB
(0800 233 352). Please provide your mobile phone number and postal address
(including postcode if you know it) – we will use this to send messages relevant
to your location in future. Alternatively, signup here: https://beeflambnz.com/user/newsletter-signup
Plus, you can go online and look back at past messages and reminders at:
Further details on oestrogens in lucerne can be found here:
- Fields, R.L., Moot, D.J., Burrell, G.K. 2017. Identifying oestrogenic lucerne crops and pre-mating ewe management. 4 pp. (PDF 0.3 MB)
- Fields, R.L. 2017. Causes of elevated coumestrol in lucerne and mitigation of the subsequent risk to ewe reproductive performance. PhD thesis, Lincoln University. 212 pp. (PDF 8.8 MB)
- Fields, R.L., Burrell, G.K., Moot, D.J. 2016. Premature mammary development in ewe lambs exposed to an oestrogenic lucerne pasture. Journal of New Zealand Grasslands 78: 41-44.
- Blog post. Effects of oestrogen content of lucerne on ewe ovulation rates