Nobilis clearly states, Once broached use immediately, I will only keep it until the next day in case any have an oily area on them where it has clearly leaked and I would re-do them but that's all, I do wonder with the lads that say they vaccinate youngsters prior to leaving the nest, they've either got their breeding spot on or they are kidding themselves, we must be doing something wrong as by now we should have eradicated PMV