Reports are coming in that some early spring calvers are already seeing higher-than-usual numbers of abortions and stillborn calves this season. Wyoming's Brett Crosby, a rancher in the northern part of that state, says he's hearing these reports from multiple cattle producers in Montana and Wyoming.
Crosby told DTN that, to this point, there have been no definitive answers as to the reason for the losses. Many ranchers suspect they are in some way tied to feed issues and stress, which have been common in these drought-stricken areas.
"Hay is so expensive right now that people are buying anything they can, and sometimes that means they get some stressed forage that will have nitrate problems," said Crosby. "They could also get into some mold. It could even be due to stress from the summer. It's hard to know for sure."
LOOKING FOR ANSWERS
For a boots-on-the-ground view, DTN reached out to Wyoming large-animal veterinarian Matthew Asay. Based near Lovell, Asay reported he is definitely seeing more losses this year, and he has been working with herd owners in the area to get answers.
"Every year we tend to have more issues early in the season than later, once calving really gets going. But this year, we are definitely seeing more losses, and I think it's a combination of different things," he said, noting that he believes more calves are being aborted due to high nitrate levels now.
"Overall, that's not something we see very often," Asay noted. "But in some cases, we've seen producers utilizing feed with higher levels of nitrates simply because forage availability is so limited. We're working through that on several ranches now. This past week, I submitted several samples to see what is going on. As a veterinarian, I want to make sure producers are using quality feed, because I know how important it is to maintain good nutrition, minerals, protein and water. But in years like this, that can be very challenging, both in terms of finding those inputs and of being able to afford them."
NITRATE POISONING DANGERS
Forages or feed with high nitrate content can lead to an accumulation of nitrites. Drought-stressed corn and small grains are common culprits, but there may also be problems with sudangrass, sorghum-Sudan hybrids and millet.
The accumulation of nitrate is influenced by weather, fertility and soil conditions. Water may also be a source of toxic nitrate levels if it becomes contaminated with fertilizer, animal waste or decaying organic matter.
If cattle ingest plants that contain high levels of nitrate, nitrite accumulates in the rumen. Nitrite is 10 times as toxic to cattle as nitrate. At sublethal doses, nitrate toxicity can lead to abortion, weight loss, reduced milk production and other performance issues. Prevention requires having feeds and forages analyzed prior to grazing or feeding them. In some cases, the effect can be diluted, but it's best to talk to a veterinarian or nutrition specialist about how to safely do this.
LEARN FROM CALF LOSSES
Every lost calf is more than just a disappointment. A lost calf is a significant setback against all the seen and unseen resources that went into preparing the cow herd for conception, feeding it through gestation, and keeping that herd bull in good breeding condition. There is no getting back that season, or those resources. Recognizing the reason behind the loss may be the biggest value that comes out of it, because it puts a producer in a position to prevent the same kind of loss in the future.
Asay says it's especially important not to overlook the value of a necropsy in a year like this. This is simply a way to determine why an animal died when the cause is unknown. It yields important information for veterinarians because it helps them effectively treat and prevent continued losses. A necropsy can identify something as simple as a lack of fat reserves in a calf, or the fact that a cow stepped on the calf and caused internal organ damage. Infectious diseases can also be spotted, helping to prevent further losses in the herd.
In cases of cattle abortions, Asay stresses that both calf and placenta are needed for the diagnostic lab.
"The lab always asks for the placenta, and we don't always find it, so if you can catch it and put it in a plastic bag, that is important," said the veterinarian. He also likes to draw blood from the dam for tests, so he advises producers to keep her close if possible. Asay cautioned that anyone handling fetal loss or a stillborn should wear gloves to protect against the rare case, such as brucellosis, where human infection is possible.
COMMON REASONS FOR CALF LOSS
NEOSPORA. You don't hear about this often, but Neospora is a protozoan ingested by dogs and wild canines. When those animals soil a cattle herd's eating areas, cows can become infected and pass it on to their in-utero calves. Over 90% of calves born to dams infected with Neospora are also infected. It is a common cause of abortion in cattle, as well as the birth of weak calves. Abortions due to Neospora infection are most common at the 5- to 6-month mark. There is a test to indicate the presence of these antibodies in fetal tissue. There is no vaccine available, so prevention turns on keeping dogs out of cattle feeds.
Asay noted that having a placenta is extremely important in diagnosing Neospora, and he said he has seen this issue within his practice area.
MYCOTOXINS. Certain fungi can produce what are essentially poisonous chemical compounds, and these, in turn, can contaminate cattle feed. These are not compounds visible to the human eye and are detectable with lab testing. The most common causes are fusarium and ergot. The risk for fungi developing is higher when moisture and temperatures are higher during the flowering stage and when storage conditions are such that they allow moisture levels to exceed recommended ranges.
Symptoms include animals that consume less feed (look for 30% or greater drop), frequent illness, a lack of response to antibiotics, convulsions, spasms, temporary paralysis, gangrene or lameness (especially in feed, ears and tail), fever, bloody diarrhea, blisters/ulcers or reddening in the mouth, fertility issues and abortion/premature births.
Prevention and awareness are the only ways to avoid this. Test feed, follow good management practices in putting up and storing feed and do whatever is possible to strengthen the immune system to make animals less vulnerable to mycotoxins.
If you're experiencing unusual losses in this spring's calf crop, reach out to your herd veterinarian or local Extension specialists for guidance.
Victoria Myers can be reached at firstname.lastname@example.org
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