Rapeseed Blindness in Roe

PSE Composites Limited


Well-Known Member
Hi Stalkers,
With the increasing amount of rapeseed cultivation has anybody come across blindness in Roe or Reds which appear more able to cope with it. Normally it would appear early in the season when food is on the scarce side.
During a discussion people were mentioning GM rapeseed alone as being implicated but i thought it was any rapeseed as we grow 00rapeseed in this country.I know it is affecting an increasing number of horses' breathing giving asthma like symptoms when in flower.



Whilst unusual it would be possible to see blindness caused by Oilseed Rape being grazed, all brassicas contain high levels of sulphur, most modern varieties are indeed double low varieties which should give a low glucosinolate level ( the compound which contains sulphur, and also interestingly gives Horsradish its hot taste) however ther double low status refers to the seed and not the young plant which would still contain high levels.
In some situations, high levels of dietary sulphur create hydrogen sulphide gas in the rumen. This can lead to sulphur-induced polioencephalomalacia (PEM), a dietary disease that can cause lesions to form in the brain. Clinical signs include a lack of muscle coordination, facial tremors, teeth clenching, circling, stupor and cortical blindness. These conditions are soon followed by recumbency, convulsions and death.
For this to occur the diet of the animal would need to be almost entirely based on oilseed rape which could be possible in times of feed shortage.


Well-Known Member
I seem to remember some years ago a Swedish friend telling me that a certain strain of oil seed rape was killing Hares and causing liver damage to Roe and Elk [Moose.]


Well-Known Member

I think i had that last saturday after a bbq, i certianly had the symptoms. is sulphur found in carling beer?


Site Staff
Swampy; yes I have had similar problems usually mixing two different formulas, grape and grain. Never again, well that is until the next time!!!


Well-Known Member
Hi Stalkers,
Stag1933 is correct.The incident concerning deer and hares was researched in Austria.The hares died of something else but the deer condition was described as a thiocyanate psychosis. Thus may be our 2 fellow stalkers suffered the psychosis.Unfortunately the confirmation of the condition may be a bit painful boys.A slice through the brain and the cortex fluoresces under ultraviolet light.Ouch!!!!
We have 3 names for the same condition.
Thiocyanate-psychosis continental Europe
PEM ...............................................North America
or CCN Cerebrocortical necrosis.....Britain

The condition is believed to be a Thiamine (B1 vitamin ) deficiency leading to a swelling of the brain with attendant features described by Humphrey. I have seen it in live sheep and farmed Red deer who were being pushed on a high grain feed to get them to slaughter weight sooner.Eating bracken can also cause it.
The Roe cases (dead) had a rumen full of grain as they had learnt to upend pheasant hoppers and gorge on the grain.A few professional stalker friends have heard of it or come across it.We are still very interested to hear of other cases.



Well-Known Member
The local Reds that I saw during the Summer were discovered couched in an Oilseed rape crop by one of the farm staff whilst spraying, apparently he was surprised and shocked by this as we are all told that there are no wild deer on the island. I observed them feeding in the adjacent cereal crop which I expect they found better tasting and more nutritious.
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