Whats OPA and NRL?Bought a lovely pen of texel x mule shearlings to add to my flock in September , every thing ok until housing a week ago three go down with twin lamb despite ample feed and lick blocks . Couldn't quite belive it classic symptoms, got vet tested no ketones so not twin lamb after 2 died post mortem revealed OPA, at that age, bought a pen load of absolute sh!te never again why do I bother no wonder they were NRL the vendor must have a serious problem and will be told , too late for me now.