Hi all, I thought I'd raise this one again in case anyone else's sheep had been shorn after applying Crovect. My tiny flock of 6 sheep has been shorn, unexpectedly early, a couple of weeks after I applied Crovect. I wrote to the manufacturers, Elanco asking if the chemical would wear off during storage, or if it would wash out with detergent and received the following reply, which I thought was pretty helpful:
"Thank you for your enquiry regarding Crovect.
Unfortunately, all our work on the breakdown of cypermethrin has been on the animal and we don’t have any data on the breakdown once the wool is stored. When the product is on the animal it is broken down by sunlight, rainfall, oxidation, dilution by wool growth etc. Some of these, depending on the way the wool is stored, will not be present once the fleece is removed - wool growth will obviously not occur.
The active ingredient in Crovect, cypermethrin, is bound to the lanolin (wool grease) in the wool and so washing with detergent would remove it. However, operator safety and the discharge of the washings would have to be taken into consideration and any regulations adhered to.
It may be worth contacting the wool processers as they may have more information on the washing of fleeces. I am sorry we don’t have all the information you require but hopefully this is of some help.
If you have any further questions please contact me by emailing ElancoVETS@elanco.com or call 01256 353131 choosing option one for technical services followed by option two for the farm team."
Hope this is helpful - I will carefully wash my fleeces, wearing adequate protection and ensuring the rinsate doesn't go near watercourses/public drain etc.