Simple Ways to Keep Abortions from Eroding Your Profits

Abortions cost U. S. dairy farmers an estimated $27 million per year.1 But the causes are many—and often difficult to pinpoint. Nevertheless, there are steps producers can take to minimize the incidence of abortions in their operations.

While they are never desirable, bovine abortions are an accepted part of life on a dairy farm. The expulsion of a fetus, which can occur any time during gestation, is reported at a rate of up to 10 percent across the dairy industry.

While that number may not seem high, experts believe there are far more of these failures that go unnoticed. In fact, studies show that only 30 percent of abortions are currently being diagnosed. And, with an average cost of $600-1000 per case, the cost of these mishaps in lost production is significant.²

So the natural response is, what’s causing these mishaps, and what can be done about it? The problem is, even when abortions are detected their causes are difficult to determine, these same experts agree.

“Coming up with a definitive diagnosis for an abortion is the exception, rather than the rule,” says Robert Sprowls, DVM, Ph.D., Resident Director, Texas Veterinary Medical Diagnostic Lab (TVMDL) at Texas A&M University, Amarillo, TX.

Infectious causes. Our first instinct is to look at infectious agents. However, Sprowls says long-term research indicates only 20 percent of observed abortions are caused by bacterial, viral or protozoan infections.

“We used to see leptospirosis and Campylobacter, but we don’t see those nearly as often as we used to,” he explained. “Better management practices include vaccinations for these and other infections. Vaccination doesn’t provide 100 percent protection, but it drastically increases the possibility of the cow carrying a viable calf to term.”

Of the organisms that can cause infections resulting in abortions, the most common ones are trichomoniasis, leptospirosis, salmonellosis, BVD (bovine viral diarrhea) and occasionally IBR (infectious bovine rhinotracheitis).

In addition to vaccinations, Sprowls says there are several other management practices that can decrease the likelihood of abortions.

Disease management. Though infectious agents are low on the list of important causes of abortion, BVD demands careful attention.

“BVD is a peculiar organism,” said Sprowls, who has been with TVMDL since 1975. You need to make sure you don’t have any persistently infected (PI) animals. If they are exposed in utero, the infection may never clear up, so they can continue to spread it in the herd,”

He explained that if the calf is exposed to BVD in utero before its immune system is fully developed, it won’t recognize the organism as a disease threat. About one-third of these BVD-infected calves die before weaning, one-third die between weaning and adulthood, and one-third survive to adulthood and seem normal. Because this last group looks normal, no one realizes they are sick, and they can infect their own calves and spread the disease to other cows that are pregnant, creating a vicious cycle.

Consequently, it’s crucial to test for—and eliminate—persistently infected animals from the herd, he says. Numerous labs offer economical, accurate tests for BVD. Both the ELISA (enzyme-linked immunosorbent assay), and the IHC (immuniohistochemistry) tests are performed on ear notches. They cost about $4 per animal and enjoy a 90 percent accuracy rate.

Studies show that only 30 percent of abortions are currently being diagnosed. And, with an average cost of $600-1000 per case, the cost of these mishaps in lost production is significant.

Sprowls says it’s not necessary to test all cows, but “if you are having abortions or weaned calf illness, that’s one of the things you really need to look at.”

He recommends segregating cows that are tested and, if BVD is confirmed, run a second test, to be sure. If the second test is positive, the cow should be euthanized, sold to slaughter or sent to a feedlot that feeds BVD-PI cattle. Otherwise, they will continue to infect any cattle they come in contact with.

Biosecurity. When new animals come into the herd, it is important to separate them, also. This can help prevent the spread of many types of infections.

“You don’t want to bring in a new set of heifers or bulls and mix them with your cows,” Sprowls said. “Keep the bulls separate for a minimum of 30 days before you turn them out with cows. During that time, have your veterinarian deal with any signs of problems and test them for contagious disease, including Johne’s Disease, Leukosis and BVD. Hopefully, if you isolate them for a period of time, the infection—unless it is BVD—will clear up.”

With heifers, Sprowls suggests segregating them from other cows until they deliver a good calf crop without any problems. Like bulls, heifers should be tested for BVD before commingling them with other cows.

Calves should also be tested for BVD, he says, because “90 percent of the time, it is the calf that has BVD PI.”

Sanitation. Sanitation and environmental conditions can also have an impact on the incidence of infections that cause abortions. To minimize the possibility of infection, avoid congregating cattle in the same areas repeatedly, whenever possible.

“When we feed them, whether in bunks or with hay on the ground, the cattle often spend too much time in that location,” Sprowls offered. “Anytime you have a lot of animals together, if you have infectious organisms, such as Salmonella, there is more chance for them to spread it.”

He notes that while moving water sources is usually not feasible, feeders can be rotated so that cattle don’t spend too much time in one area of the pasture.

Stress, nutrition and genetics. Sprowls says noninfectious sources are “certainly the number one cause of abortions,” especially in an era when vaccination programs are comprehensive. Noninfectious sources include stress, nutrition and genetics. These causes are the most difficult to pinpoint.

In late term abortions, something as simple as lack of water can contribute to miscarriages. Obviously, this can occur in hot weather, but also when snow or ice might keep cows away from water supplies. In early term failures, lack of optimal health can contribute to abortions, especially when subclinical illness is present.

Poor health might result from inadequate nutrition, which, when combined with deficiencies in trace minerals and vitamins, can result in miscarriage, Sprowls stated.

“Nutrition is very important, especially in late pregnancy when protein and Vitamin A are crucial,” he said. “Pregnant cows need to be on an adequate nutritional program, one that includes sufficient protein. That’s usually where we fall short.”

Sprowls surmises that the trend to breed animals to gain weight and produce high quantities of milk may also contribute to abortions.

“Calves are bigger now, and we actually have higher quality cattle,” he explained, “that can come with genetics that may not maintain pregnancy as effectively. It’s a doubled-edged sword: those high milk producers are often more likely to slip a calf. And, when cows are suckling a large calf, they will slip a calf more frequently, too. In the past, they didn’t have that level of nutritional drain and stress.”

Other risk factors for abortion are the age of the cow, as well as its history of previous abortions.

Other risk factors for abortion are the age of the cow, as well as its history of previous abortions.

1. Review: Cost of Reproductive Diseases and Conditions in Cattle, D. S. BELLOWS*, S. L. OTT†, and R. A. BELLOWS‡,2, PAS *Purina Mills, Inc., St. Louis, MO 63144; †USDA-APHIS, Centers for Epidemiology and Animal Health, Fort Collins, CO 80521; and ‡USDA-ARS, Fort Keogh Livestock and Range Research Laboratory, Miles City, MT 59301

2. Abortions in Dairy Cows: New Insights and Economic Impact, Augustine T. Peter, Department of Veterinary Clinical Sciences, School of Veternary Medicine, Purdue University. http://www.wcds.afns. ualberta.ca/Proceedings/2000/Chapter19.htm