The summer of 2011 has been extra difficult for southwest Missouri livestock producers according to Eldon Cole, a livestock specialist with University of Missouri Extension for more than 40 years at Mount Vernon.
"I believe there have been more deaths of cattle and abortions in southwest Missouri this summer than in a long time," Cole says. "It's hard to tell how many open cows will be found at pregnancy check this fall. It all adds up to a big loss for all sectors of the beef production enterprise."
Although official records on cattle deaths in the region are not maintained, the rendering plant located in southwest Missouri reports that their pick-up calls are easily more than twice the amount as this same time period a year ago. Plus, there are a number of cattle deaths they are not called on.
Summer heat, winter coat is deadly combo
There are a variety of causes for the cattle deaths but Cole says most will ultimately be blamed on the unusually hot and dry weather experienced in a big part of the Midwest.
"We know elevated body temperatures can cause stress that, if not reduced, results in death," he says. "The forage we rely on a lot, fescue, can also be a factor. It contains a fungus capable of producing a toxin, ergovaline." Ergovaline interferes with heat dissipation from the cattle's body and it causes them to retain their long hair coats.
"This hair coat can be likened to us wearing our warmest winter wear on a day when the heat index is 110 degrees or more," Cole notes. "A number of the animal's bodily functions -- like respiration, digestion and reproduction – can then be compromised."
Cole visited some Kansas feedyards the first week of August (when the heat was still prevalent but not at its peak) and he says the cattle he saw with their "winter coats" on were under heat stress.
"I'm not sure where all of the stressed cattle came from but one manager said the lot had received a large shipment from southwest Missouri a few days earlier and that they were 'fescue cattle.' During a hot day they lost eight head and six were from the Missouri group," Cole adds.
Cole says that visual demonstrated to him that producers have to work harder at converting and diluting our "hot" fescue pastures and hay fields in southwest Missouri.
"Increased attention should be paid to selecting cattle with the genetics to better tolerate the negative effects of ergovaline. We have seen cattle within all breeds that seem to handle the heat better than others. Let's include early hair shedding and heat tolerance more in breeding stock selection," Cole advises.
Besides deaths and subpar production from fescue, there can be other forage-related problems such as nitrates in summer annual forages, and stunted corn. Pigweed, Johnsongrass and perilla mint are known poisonous plants that may be grazed by hungry cattle given an opportunity to eat something green during dry, hot weather when pastures are short.
The Johnsongrass and sorghum-sudans also have the potential to kill due to a compound known as prussic acid. "We have seen cattle die in pastures containing Johnsongrass but it's not always clear whether the cause was nitrates or prussic acid since very few are posted by a veterinarian," Cole says.
As summer turns into fall, rains should help the pastures rebound and death losses will drop. Still, Cole offers this word of caution: If forages were harvested for hay or silage and there is a chance the nitrate level is high, invest in a lab test for nitrates for less than $10.
"Most nitrate-bearing feeds can be managed if you know the level of nitrates in them," he says.
For more information on coping with the recent summer weather, contact your area MU Extension livestock specialist.
Eldon Cole's photos of cattle in various stages of heat stress can be found and downloaded under the "Livestock" tab at www.flickr.com/photos/MUExtension417
Source: MU Extension Southwest News Service