After reading this post, I had to go out and try it. I bred three mares, so I brought them each into the barn so there would be no wind. I asked my son who is 13 and my daughter who is 16 to come out to the barn with me. I explained what I was going to do and that I was skeptical. They looked at me like I was crazy. I told them I wanted to have each of us do the nail test individually and then share our results.
1. Grace-usually gets really big over winter and its hard to tell if she is bred. The nail didn't move for me, but both of my kids got "filly" Smooth hair on her tail.
2. Lady- all three of us got "colt" however the hair on her tail is NOT smooth. Its all ruffled up. (I am SOOOO hoping for a fewspot colt out of her to keep)
3. Feather- The nail barely moved for me at all, but all three of us got "filly" however she has smooth hair on her tail
It will be neat to find out if this "test" is accurate. If nothing else, it was fun to do!