The lights are very effective in terms of getting mares to cycle. I never had very good luck with the hormone injections bringing up a breedable follicle back when I worked at a breeding farm. The mistakes a lot of people make are 1.) not having enough wattage - the light needs to be *bright* - ordinary stable lights won't work. There may also be something about the color spectrum of the light, but I'm not sure and 2.) not starting early enough. We usually put the mares under lights in September.