A ranch weans four groups of calves, all from separate pastures and breeding groups. They are placed in the same drylot to be fed, and three weeks later, some calves are dealing with bloody diarrhea. With the time of year and situation described, coccidiosis is high on the list of possible issues.
In the most recent episode of the “Bovine Science with BCI” podcast, Kansas State University veterinarians Bob Larson and Brad White look at this case of potential coccidiosis in weaned calves.
Larson explains there are other issues that can cause bloody diarrhea, like Salmonella or any other intestinal disease that cause damage to the intestinal lining.
One of the first factors to investigate is feed rations. In this case, these calves were being fed a corn, corn-gluten and soy hull mix with free-choice hay. Larson explains this is a rather fibrous diet with less starch, therefore acidosis and other related digestive tract issues can be eliminated.
The Prognosis
Studying the feces is another way to analyze the situation. Typical signs of acidosis include runny feces, sometimes containing gas bubbles, according to Larson. But he also adds that this is never a perfect test and to keep your options open when determining the prognosis.
To further understand feces tests, Larson explains that frank blood, often appearing bright red in color, indicates the damaged gut is further back in the digestive tract and the blood hasn’t been digested. When the blood is digested, like with abomasum ulcers or earlier tract issues, it appears black in color with a tar-like texture. In this ranch’s case, calves are presenting frank blood.
For more diagnostics, Larson says fecal floats are an option. There are different types of coccidia organisms that infect cattle in varying strengths. He warns these protozoa of the coccidia organisms will invade into the cells that line the intestine and then destroy the intestine as they multiply. But sometimes these protozoa do not show up in a fecal float, so it is important to not rule out coccidiosis if that is what is suspected, and the fecal float is negative.
White adds most calves will have coccidia organisms in their systems already.
Larson explains it is common for most mammals to have these organisms present in their systems, and the coccidia are specific to animal species. So, a high number of these organisms would confidently indicate coccidiosis, but smaller numbers should not be looked over either.
Larson and White both agree coccidiosis seems to be the issue with this ranch’s case, so the next item to address is where or how the calves contract it.
Control and Prevention
“They had it themselves — it’s not that they got it from somebody else necessarily,” Larson explains.
But he notes cattle can still get sick if they encounter calves carrying a coccidia species they haven’t been exposed to.
Young cattle like these are more susceptible to coccidia protozoa because they haven’t had time to build an immunity to them like older cattle would. However, there are a variety of populations of coccidia, so they cannot build an immunity to all types.
“There’s some challenges there keeping everybody on track nutritionally, and I’m mixing cattle from different sources, which probably means they are bringing in different types of coccidia,” Larson says.
White adds coccidia can be spread by fecal or oral contamination, and this setting is ideal for it. However, he also mentions their ration has an ionophore in it that should help control the contamination.
Rumensin or Bovitech are common ionophore products that provide control, but Larson says we should think of them as ways to control the multiplication of organisms. If cattle are at high levels of protozoa already, these additives are ineffective. But they are a crucial part of control and prevention.
For early precautions, Larson recommends feeding ionophore products like Decoquinate or Amprolium as they, “will do a better job of killing those organisms at other stages in the life cycle.”
Once calves are settled from weaning and their stress levels decrease, then they can be switched to other ionophores in their daily rations.
Larson says these treatments can be administered in feed or water, but it is often better to treat individual animals. Then, the whole group can be started on the ionophores for further prevention.
Managing environments and their conditions and limiting nutritional and weaning stress is also beneficial in the prevention of coccidiosis.
Larson reminds producers: “It takes consistent attention to the details to try to keep these problems at bay.”
