sexed semen protocols

[Hilltop Genetics]

I have some heifers I am going to breed with sexed semen here next month. they have all had multi min 90, and have purina availa 4 mineral. I am going to breed them on a natural heat, they have been cycling every 21 days.
my question for everybody is: do you recommend breeding later in the heat and giving a shot of GnRH?

 

[Bar QH]

We have bred 3 drafts, all sexed semen off 7 day cidrs. Heat check religiously every 3 hours. Try to wait at least 3-6 hours after the first standing heat. Used to wait 12 hours after they quit standing. Now we breed about anytime, we breed morning and night if we had one start atanding at 3pm we breed her at 7pm with the others that were in heat prior. I can't see a pattern that seems to matter. We have ran @ 66, 72, and 74% on all sexed semen. Always give a shot of gnrh as soon as we pull the ai gun out. Everything is on free choice vitaferm.