Late term mycotoxin abortions

Every spring ranchers wait impatiently for that first calf, checking the herd while feeding and watching the cows start to bag. Finding a dead premature calf or having to pull one can be heartbreaking, not a good way to start calving season. Every year one or two percent of cows will slink calves during the winter, it is unfortunate but normal. Late term stillborn calves can have many different causes: infection, bacteria and toxins, if the number is higher than normal having the calves posted is recommend by veterinarians.

Doctor Bleaux Johnson, DVM of West River Vet Clinic in Hettinger, North Dakota has been seeing a higher number of late-term abortions than normal. They have been having the ranchers collect the calves along with the placentas and sending them off for necropsy. “Some come back with no problem found so they are most likely caused by stress or nutrition. More of them have been fungal caused by moldy feed and a few septicemias but so far none have been infection based like IBR, BVD, or leptospirosis which we vaccinate for. We try to avoid running cows through the chute to vaccinate them this late in the pregnancy as it can cause more stress and can lead to abortions.”

The placenta in a pregnant cow is the portal from the mother’s blood supply (carrying nutrients and oxygen, but also bacteria and viruses) to the calf. If this critical organ is compromised, then the calf may become oxygen deprived or become infected, all resulting in death. When germs are found, they are often more environmental than contagious in nature. Often it is believed that cattle breathing in mold spores can be the worst, but Dr. Johnson says with most ranchers feeding outside with a bale processor, inhalation isn’t the problem as much as ingestion is.

“I feel most of the mold is ingested and enters the bloodstream from the GI tract. The fungus enters the calf through the placenta, causes infection and death. Most cows don’t show any symptoms other than having a dead calf. Often we see them retain the placenta too. There is a magnitude of different fungals; some cause death or abortions others they can adapt to. If you can see mold, minimize usage of that feed during the last trimester. Feed piles should be managed and our focus should be on proper nutrition and supplements. The last month of pregnancy the cows are very susceptible, we need to be feeding better feed to the cows now so they are in good shape for calving,” Dr. Johnson said.

“Our hay sat in the fields after baling, soaking up moisture and a lot of the late corn has been moldy, and cows that are grazing on stalks are ingesting it. Ranchers should work with a nutritionist and monitor feed sources for mold. Silage can have pockets of mold and if the feed is moldy, wait to feed it until after calving. Some of the cows might look fine but be deficient in essential vitamins and minerals since the feed quality isn’t as good this year,” said Dr. Johnson.

Dr. Johnson has noticed that most often there will be a rash of stillbirths and by the time the results are back from the lab the crisis has passed but knowing the cause is what is important to help prevent it from happening again.

Mold and Mycotoxin Problems in Livestock Feeding for Penn State Extension; February 18th 2016.

Written by Richard S. Adams, Kenneth B. Kephart, Virginia A. Ishler, Department of Dairy and Animal Science, Lawrence J. Hutchinson, Department of Veterinary Science, and Gregory W. Roth, Department of Agronomy

“Weather conditions during growing and harvesting seasons may appreciably increase the incidence and degree of moldy feed and mycotoxin problems from year to year. Cool, wet growing seasons may delay grain maturity, especially for corn, and result in mold and mycotoxin formation in the field. Fusarium toxins are more likely to occur under cool, wet conditions during growth, harvesting, and storage. Hot, humid conditions favor the development of aflatoxins. Delaying harvest to increase maturity and reduce moisture levels, or to avoid muddy field conditions, may result in increased mold growth and mycotoxin formationn. Storing grains, feedstuffs, and forages at moisture levels beyond recommended ranges or in poor storage units also may increase mold-related problems. Recent knowledge indicates that these problems sometimes may be the cause of previously unexplained production and health problems. Mycotoxins may be present in feeds that have little or no obvious mold present.

Moldy Feed Effects

Moldy or musty feed won’t always contain dangerous mold poisons or mycotoxins, but the presence of considerable mold in itself may adversely affect production and health. Digestibility of the ration may be decreased sufficiently to reduce energy content by 5% for ruminants. Thus, it is best to discount energy values (book values or estimates via testing) by multiplying them by 0.95 when feeds have appreciable mold. Such feed is also less palatable and may lower the intake of energy, dry matter, and critical nutrients. This may considerably reduce milk production, growth or weight gains, and depress resistance to metabolic and infectious diseases.

Reductions in production performance and increases in health problems from moldy feed are often moderate if mycotoxins are not present. For example, a 5 to 10% drop in performance may be typical with mold infestation, whereas mycotoxin contamination leads to greater losses in production, even when mold is not readily apparent.

More problems with mycotic abortions and respiratory disorders may result when a considerable amount of moldy feed is used. This may happen due to a high content of mold and mold spores in the air or in the ingested feed. (Farmer’s lung is a disease that may affect humans in a heavily mold-infested environment.) The placenta of aborted fetuses should be examined for the distinct signs present in most mycotic abortions.

Sometimes mold spores are counted on moldy feeds to obtain an indication of the extent of molding and relative risks in feeding them… Since some moldy feeds may not contain an elevated spore count for a variety of reasons, spore counts sometimes underestimate the degree of mold present and potential risks involved.”

Aborted calves should be collected as soon as possible along with the placenta, placed in a clean plastic bag and refrigerated until delivery to your local veterinarian. There is an expense for necropsy but saving just one calf will more than pay for it.