cowpoke1977 said:
We wanted to set up some cows for this protocol on Saturday. One of them got in with the herd bull and got bred about 3 weeks ago. Should I give her a shot of Lute tommorow before we put CIDR in Saturday?
You're going to need more then 48 hours between the Lut and CIDR. Someone can correct me if I'm wrong, but here's the general idea behind how the products work: the female develops a CL every 3 weeks. It goes through its growth cycle, and when she isn't pregnant she goes through Estrus ~3 days after the CL "matures." If she becomes pregnant, she maintains the CL (but now it has a different name that escapes me). The idea behind a CIDR is that it provides the hormone (prostaglandin F-2alpha) which mimics pregnancy and maintains the CL in the state just before estrus would occur. By hitting the pause button, you can synchronize a group of heifers at different phases because they will still develop their follicles to that point without going further. The Lutalyse causes the CL to lyse (think of a pimple popping), and then a non-pregnant female will be in estrus 3 days later ready to breed--or it will terminate the pregnancy that was being maintained.
Now for why your plan won't work: if you Lut her 2 days before the CIDR goes in, you'll have 2 things working against you. The less likely--maybe the Lut isn't active enough and the CIDR presents PGF2A which maintains the pregnancy anyways (unlikely but possible). Or, the most likely, she will be at the wrong point in her cycle for the CIDR to work. It will take her more than just the 5 days of the CIDR to develop a follicle that will be ready to be bred.
Now before anyone rips me apart on semantics, I'm sure some of the terminology (when it's a CL vs follicle) above isn't 100% on the mark because it's been a long while since I've researched this, but that's my best shot at conveying the general concepts.
