We have cattle and horses which attract flies. For a couple weeks we have used Purina mineral feed tub with Altosid. However, after further thought I don’t want that stuff in my cattle or in my soil. My ultimate plan is to implement several more natural fly predators including my chickens. My concern now is, once the altosid tub is removed how long do I need to wait to put my chickens on the field? I don’t want my chickens getting sick and we eat their eggs. Thanks!