You are putting in embryo transplants using a heat detection method? Maybe this is normal in other places, here using a synch program is the norm. My AI course taught 45 - 60 days post calving for AI. We've always used 55 days after calving (vet suggestion) for AI and for embryos I would wait the 55 days (minimum) and then put them on the synch program which takes 17 days (day 17 you put in the 7 day old embryo). The ones we do I attempt to keep them so they are calving exactly one year after their last calf was born (give or take a few days for weekends). Embryos are just too pricey to take the chance of putting them in too early imo. The key is condition - they have to be healthy if you want them catching and retaining the embryo. If you do the synch program then you can just watch them at the time they are due for heat and/or mark their tail heads Take out any cow that doesn't cycle - or better yet if your tech is experienced he will be able to tell you before thawing in the embryo if the cow is at the right stage of her cycle.
Just a couple notes about heat detection from when I took my AI course:
70% of standing heat occurs between 6PM and 6 AM
22% of standing heat occurs between 6AM and noon.
8% of standing heat occurs between noon and 6PM
One study showed that 28% of of natural estrus cows display heat during the darkness - only 3% of synchronized cows display heat during the darkness. The same study showed that a person watching twice a day (30 minutes each watch) only sees 62% of the cows in heat.
If your cows are wilder or not used to having you around though stay as far away as possible and use binoculars. Cows that are less used to humans will often not display signs of heat if a person is around.
What I have experienced in my own herd - my girls tend to be more active at dusk and when they first wake up. The other time there is a lot of commotion is feeding time. The usual rule though is dusk and dawn. My cows are lazy and sleep in!lol
Signs of Heat- the better you know your cows the better this will go. For example - if you have a shy cow that suddenly becomes bossy pay attention. Some normal signs though include:
Pre Standing heat -
attempts to mount herd mates, will not stand to be mounted, restless, aggressive, bellowing, very small amount of watery mucus
In Heat (standing heat):
stands to be ridden, bawls frequently, nervous and excitable, rides other cows, off feed, first cow up, vulva moist and red, clear mucous discharge, eye pupils dilated, tail held to the side
After Heat:
no longer stands to be ridden, clear mucous discharge from vulva
Some cows are really easy to spot - they'll show all the signs. Other cows won't do anything. If you plan to do this every year keep notes on each cow. Our instructor suggested we do this and I am glad I did. It's the best way of learning their individual quirks and being able to teach yourself the more subtle things to look for.
One other thing - you have cows that are getting pregnant with their second calf - this is the hardest time to get pregnant for a cow (with the exception of old age). My embryo technician recommends not using cows getting pregnant with their second calf for embryo recipients. If you want to artificially inseminate them then I would give them the 55 days just to let them get into shape because of their age. Good mineral is essential too if you want them to catch. Good Luck!!
