Hilltop -- I neer breed anything here until they have absolutely quit doing anything, and then wait 4-6 hours on most of them. I want them all done, tired and resting before I go breed them.
Most cows will stand for atleast 12 hours, many if not most of them closer to15 hours depending on time of year. Doesn't matter to me when they started, but I want to know when they quit trying to ride anything else.
Male cells swim faster but do not live as long, so over the long haul -- (MAny cows) you will see a better bull ratio if you give them a little more time. For example, if you get anxious and breed them just when they are getting done, you could be 50/50 or slightly heavier on hfrs.
If you wait for several more hours, the odds will lean toward more bulls -- it has worked for me for lots of years, plus, your conception will be VERY good.
TIP -- Always breed the cow when it is convenient for "HER", not for "YOU". Lots of cows are rebred every year for a simple reason -- and that is timing!
Not gonna work for every one or every cow, but the averages will show over time!
Good luck to all -- Terry