I personally think you're best off just making sure you've got plenty of bull power available for their normal 21 day cycle, and then working as best you can to improve both natural genetic fertility (cull those who don't settle within 45 days), and making sure you've nutritionally got them where they need to be. If you're not "challenging them" to be tops in fertility (by not culling hard for lack of fertility, and by using artificial crutches to get them there), you'll never be able to differentiate between the "good ones" and the "bad ones". You'll be keeping those "problem breeders" in the herd, and then you're only working backward... We all know that there's some that will breed no matter what......... and there's some that just WON'T breed too. Which one do you want your herd to be like? If you don't challenge them, and cull for it, you'll never get there. I know guys that specifically try to breed them when they're somewhat nutritionally challenged, just so that they will only end up with the most fertile ones calving. Don't know how that can be afforded... you'd have to ask them that... but I can tell you that they don't have much for breeding issues or open cows anymore!
Artificially screwing with their natural fertility cycle can also potentially have some unintended negative consequences. Is it worth it just to get that cycle down to maybe 12-15 days instead of 21? That's all that Lutalyse really gains you.
"Cowboy" on the steerplanet website explained the Lutalyse thing well, and pay attention to the red letter warning (my emphasis):
- County Champion Poster
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Reply #7 on: May 19, 2008, 11:24:13 PM »
Every one needs to keep in mind a few simple rules for the breeding cattle --
First -- Prostoglandin (Lutalyse or Estrumate) will only work on a cow that is a: cycling and b: mid-cycle WITH a functional CL.
Any time you inject a cow that cycled less than a week earlier or one that has never cycled , you will in most cases FAIL to get her to come into heat with that shot.
A cow that has calved say 30 days ago, and has so far not cycled, will not come in with a single dose of Lutalyse -= period!
A cow that has cycled 2 days ago will not come back in -- period!
If you feel you need to try and bump a cow forward in the calving season -- a Cidr (Progesterone based product) will act as an artificial CL. It fools them into thinking they are about to cycle back, and alot of them will before they normally would on their own.
These drugs are not cure-alls, and I see a lot of questions or comments directed at the magic drug Lutalyse. It is not a magic drug, it is a natural occurring hormone already in the cow's uterus. We , by injecting them with it, are giving them hundreds of times the normal amount present, and it over-rides their natural balance -- tells the CL to go away, and a follicle is formed after all progesterone is gone from the system. This works well in normally cycling cows, buy it will do nothing for them unless all the above are met.
Hope this helps every one get a handle on when to use what -- repeated shots in some cows that are not receptive CAN, and some times does, make them immune to responses later on. Use this and any other drug with discretion, and they will work much better!
Best of luck on your breeding season!
Terry