Dr. Tom Van Dyke
By Dr. Tom Van Dyke
Reproduction is one of the most important aspects to any dairy operation, so the smallest improvements can mean big returns. Any chance to help improve breeding is an opportunity.
One of the major causes of reproductive failure reported on farms is ovarian follicular cysts.1 Ovarian cysts can cause over expression of heat, irregular cycling and can cause the cow to become infertile.2 A treatment of GnRH can help keep ovaries healthy by clearing out these ovarian cysts that may be standing in the way of getting a cow pregnant.
In a 2007 study of dairy producers, almost 70% reported having instances of cystic ovaries occur in their herd.3 This condition is estimated to affect at least 1 million dairy cows in the United States annually.2 It also is a major cause of infertility and economic loss on farms because cows are infertile as long as the condition persists.2
Ovarian cysts occur when a follicle has persisted more than 10 days and has become larger than two centimeters in diameter.2 GnRH helps rid the ovary of that follicle so a new one can take its place, which activates the process leading to estrus.1
By treating ovarian cysts, GnRH serves two important functions that cause the ovulation of a dominant ovarian follicle. GnRH causes the pituitary gland to secrete both luteinizing hormone (LH) and, to a lesser extent, follicle stimulation hormone (FSH). LH, in concert with other changing levels of hormones, causes ovulation.1
Along with using a GnRH to treat ovarian follicular cysts and help keep herds calving on schedule, these additional techniques should be considered for higher conception rates:
- Sick or stressed animals are difficult to breed. Make sure to follow proper health protocols to avoid diseases that often accompany changing or stressful weather like coccidiosis and BRD.
- Don’t overcrowd heifers or cows. Leaving adequate stall space allows cows enough time to rest, which is essential to all aspects of production.
- Stack the odds. When choosing semen from an A.I. company, ask about bulls that are designated to improve conception rates in herds.
- Pay attention to heifers and keep them healthy. Their future productivity can depend on the choices you make now because diseases can have long-term effects on heifers.
- Know the numbers. A missed heat cycle can cost a producer as much as $294 and a missed pregnancy costs an average of $450.5 Work with your veterinarian and/or your A.I. technician to create a successful breeding program to avoid these losses.
Because fertility is such a key component to profitability in a herd, producers need to be sure they are using a leading and trusted brand of GnRH to keep cows healthy and ready to breed. Profits and reproduction go hand in hand, and a better breeding program can mean certain returns in an uncertain economic time.
- Dr. Tom Van Dyke is a manager of the Merial Veterinary Services team.
1Martinez MF, Mapletoft RJ, Kastelic JP, Carruthers T. The effects of 3 gonadorelin products on luteinizing hormone release, ovulation and follicular wave emergence in cattle. Canadian Vet J 2003;44:125-131.
2Garverick H. Ovarian follicular cysts in dairy cows. J Dairy Science. 1997;80:995-1004.
3Data on file at Merial.
4Meadows C. A spreadsheet-based model demonstrating the nonuniform economic effects of varying reproductive performance in Ohio dairy herds. J Dairy Sci 2005;88:1244-1254.
5Fricke PM, et al. Pregnant vs. open: Getting cows pregnant and the money it makes. Proceedings, Western Dairy Management Conference 2005:49-62
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