Pouring over your herd records, you note an unusual breeding pattern for a group of cows. A few cows seem to be in heat every few days, while others haven"t exhibited any signs of heat. You look back a few months, and see that while the number of animals with that same pattern changes a bit and different cows fit into this group, it becomes evident that you have a persistent problem.
The cows that exhibit frequent heat are prime candidates for a cystic ovary diagnosis. But don"t be surprised if the cows not showing heat also have this disorder. It can be a tricky problem to identify and manage because cysts are dynamic and symptoms are not always easy to spot.
Cystic ovarian disease affects about 10 to 13 percent of cows, with a range of 6 to 23 percent or higher, according to various studies, explains Michael O"Connor, Penn State University extension dairy specialist. That means about 1 million cows are affected annually by cystic ovaries.
Here is the latest information on what researchers have learned about this reproductive challenge.
Q: What are cystic ovaries?
A: Cystic ovaries, ovarian cysts and cystic ovarian disease are all terms that are used to describe the condition in cows whereby a follicular structure grows to — and surpasses — ovulatory size but fails to ovulate. In other words, the follicle grows, gets bigger than it should, and then does not ovulate. This prevents the normal estrous cycle from occurring and prolongs the time to first service and timely conception.
The definition of cysts has changed over time. They are currently defined as follicular structures that are about 25 or more millimeters in size (or about 0.98 inches) that persist for at least 10 days in the absence of a corpus luteum. They are often accompanied by one or more other large follicular structures and can be either luteal or follicular in nature. Follicular cysts are the most common.
While it sounds strange, cystic cows can either be anovular (non-cycling) or cycling irregularly. Usually, it"s a matter of the cows not cycling.
Q: What causes cystic ovaries?
A: There is not a single cause; rather, there are a number of contributing factors to this condition.
Most cows are affected by this disorder within the first 60 days of lactation. "This is also when cows experience the most health disorders and are under metabolic stress," says O"Connor. Therefore, there seems to be a strong correlation between the incidence of health or metabolic disorders in early lactation and the development of cystic ovaries.
Twinning, dystocia, retained placenta, ketosis and uterine infections all increase the odds of cystic ovaries, especially for cows in their second and later lactations. High milk production has also been implicated as a cause, but research shows that cows either produce an equal amount of milk or more milk while they are cystic.
In a collaborative study, researchers at Colorado State University and Cornell University also found that cows that were over-conditioned (a body condition score of 4 or greater) at dry-off were 2.5 times more likely to develop cystic ovaries in their subsequent lactation than their herdmates with average body condition (a BCS of 3- or 3+).
In addition, there is a slight genetic predisposition toward cystic ovaries; however, the heritability is extremely low, says O"Connor. "In the 1970s, Scandinavian researchers culled heavily against sires whose daughters had a higher rate of cystic and were able to show improvement," he says. "But that was a much smaller population than the U.S. herd and it is not currently a realistic approach in the United States."
Q: What"s the best diagnostic option?
A: Rectal palpation is no longer the preferred method.
"Since cows with cysts can either be anovular or cycling, palpating for cysts is a poor method for assessing the true cyclicity status of the cow," says Paul Fricke, University of Wisconsin extension dairy reproductive specialist. "We classify cows by cyclicity status as either cycling or anovular based on blood progesterone at various times and/or transrectal ultrasonography."
Research at North Carolina State University found that the overall correct diagnosis of cyst type was only 51 percent for palpation. Ultrasound users were correct 85 percent of the time. Other studies show similar findings.
However, Fricke says not to get too hung up on diagnostics. "We are not overly concerned with whether or not a cow has a cyst on her ovaries. We are more concerned with whether she is cycling, and this is more difficult to assess," he says. Ultrasound, again, offers a good means to answer that concern.
Q: Should you treat cysts?
A: There"s no simple answer. About 20 percent of untreated cysts disappear spontaneously. However, treatment for those that remain depends on which type of cyst it is, and that goes back to getting a correct diagnosis.
If you know the cow has a luteal cyst, treatment with a labeled dose of prostaglandin is usually successful. If you know the cow has a follicular cyst, then administering a labeled dose of GnRH usually induces ovulation of a normally growing dominant follicle rather than the cyst itself, which is a desirable outcome.
The use of a synchronization protocol, like Ovsynch, combines both principles and helps to effectively deal with cysts, no matter which type. Also, progesterone inserts, combined with a prostaglandin, have also been shown to be an effective treatment, with little statistical difference between the methods.
Since either method works, experts recommend that you evaluate cost, especially given the current economic climate. Research at the University of Florida, published in the August 2006Journal of Dairy Science, shows a $7 to $11 advantage for the Ovsynch protocol. When asked if the figures in the study were accurate for the current economy, Albert DeVries, study author and University of Florida dairy specialist, says that the economic values are still valid. "Prices have changed some over time, but the bottom-line of the analysis remains the same," he notes.
The bonus of choosing either of these methods is that you are working toward increasing pregnancies and decreasing days open.
"I tell dairy farmers and veterinarians not to focus on the cysts," Fricke explains. "Rather, focus on getting cows pregnant, which we can do with a synchronized breeding program. If you can get a cystic cow pregnant, then you have solved the problem.
Dairy farmers need to focus on cystic ovaries due to increasing scrutiny of all practices in the industry. This is just one area that could be misinterpreted by non-ag audiences.
According to an invited review in the September Journal of Dairy Science, concerns about the welfare of animals typically include three areas:
Is the animal functioning well?
Is the animal feeling well?
Is the animal able to live according to its nature?
At first glance, it seems like something is different with cystic-ovary-cows. It used to be, you could always tell a cystic cow — she was the one constantly in heat. But now, cystic cows may or may not show heat, and may or may not be cycling, making it much more difficult to determine which cows have cystic ovaries.
However, maybe memories are a little faulty when it comes to cystic ovarian disorders, and farmers can address these questions regarding this challenge in a positive way.
Most ‘cystic" cows do not show extended and intense periods of estrus, says Paul Fricke, University of Wisconsin extension dairy reproductive specialist. "This is true today, but it was also true in the past if you take the time to read the older reproduction literature," he argues.
Michael O"Connor, Penn State University extension dairy specialist, suggests that focusing on and improving the management of transition cows addresses both concerns — it lessens the odds of cystic ovary disorders and increases the health and well-being of your animals. "Good management is good animal welfare," he concludes.