I ended up with 7 heifers out of 8. My friend who used it on 30 ended up with around 2/3 heifers. I'm still not sure if it works or not. To put things in perspective I have family that has 80 commercial cows. They used nothing but natural service bulls and had 75% heifers. If you are gonna make a judgement you should probably use this product for a couple years to sort out the freak years when you are just heifer heavy.