A University of Western Australia researcher has unearthed evidence that points at a possible connection between oestrogenic pastures and ram fertility.
While it's long been known that grazing on oestrogenic clovers can have serious implications for ewe fertility, Dr Kelsey Pool, a research associate under the Lefroy Fellowship, has found that rams could also be at risk.
Dr Pool has found that when directly exposed to phytoestrogens, compounds in plants that can have oestrogen-like actions, ram sperm function is negatively affected.
She is now conducting further tests to see if those results bear out in the actual ram, comparing semen quality from rams on either oestrogenic or non-oestrogenic pasture.
"We're running something in a commercial system at the moment where rams are either grazing oestrogenic pastures or not and we're checking their reproductive function each week to follow along to make sure if that is actually the case," she said.
"My background is already in sperm biology and ram fertility and reproduction.
"I joined a team that was already looking at the effects of oestrogenic pasture on female reproduction and I just thought it was weird that nobody had ever tried to test the male.
"We've had this issue of oestrogenic pasture for 70 or 80 years and the effect on ram reproduction is not really explored."
The rams that are currently grazing oestrogenic pastures will be tested again next breeding season to see if any effects on fertility have continued.
Dr Pool said in the in vitro studies they had seen reduced sperm motility, greater sperm DNA fragmentation and increased production of reactive oxygen species, which can be an indicator of the lead up to cell death.
"Another thing to think about is a lot of rams during that non-breeding season, when they are grazing this pasture, that's when you're collecting for semen cryopreservation and doing some of your collections for AI so if you've got poorer semen quality that could actually have quite a significant economical impact further down the track," Dr Pool said.
Dr Pool has also been doing research using fruit flies that indicates if both parents have been exposed to phytoestrogens, the fertility of the next generation of animals may also be affected.
"We've already got some results that suggest that it does run down not one but two generations, showing reproductive differences due to what their grandparents ate two generations back," she said.
"I'd be interested again to see if that translates again into sheep or potentially even humans as well."
With the impending birth of lambs whose mothers have been exposed to oestrogenic pastures, there will soon be more data about how reproduction can be affected in subsequent generations.
"We [the larger team working on phytoestrogens] also have a study looking at whether lambs that have been either been exposed when they were in the foetal stage, when their mothers were in that last gestational period, or if they're exposed during the lactation period, if that has an effect on their reproductive tract and potentially their reproduction as well," Dr Pool said.
Dr Pool is also quick to reassure producers not to panic about their rams being affected by short periods of grazing on oestrogenic pastures.
"From a reproductive biology perspective, I probably wouldn't expect that short term grazing of a week or less is going to have an immediate effect or long lasting effect," she said.
"What we're more interested in is covering the full spermatogenic cycle, which is about eight weeks in a ram and seeing if we can detect changes along there to figure out at which point of the spermatogenic cycle these endrocrine disrupting compounds could actually be having an effect."