Not to hijack the other thread, but to discuss the subject; on the topic of fly control, we put fly tags in the calves, and feed Vigortone with IGR. The yearling heifers, 2,3, and 4 year olds are using quite a bit of mineral, and it is helping keep the flys down. The cows over 5 are not using as much mineral, and have a lot more flys. I think that IGR helps. I am also wondering if older cows mineral requirements are less. What is everyone else's experience?