A few years ago cattle from an American feedlot went down during transport to a packing plant and others developed severe lameness. This condition was eventually labelled fatigued cattle syndrome and became a huge animal welfare issue due to the appearance of severely lame, non-ambulatory cattle.
Initially beta-agonists were incriminated but numerous studies have essentially proven it was not due to beta-agonists but a combination of other factors that precipitated this condition. Coming out of this discovery were a number of preventive measures feedlot operators could use to prevent this condition from arising.
Dr. Dan Thomson of Kansas State University and a team of researchers in production animal medicine determined several stressors lead to fatigued cattle syndrome (FCS).
FCS has some characteristic symptoms but of course they can be confused with other syndromes such as acute laminitis due to grain overload, and selenium/vitamin E deficiencies. Symptoms of FCS include a strained pattern of breathing as well as very slow movements leading to non-ambulatory cattle. In severe cases there has been sloughing of the hooves.
Contributing factors to FCS are possibly preventable. The heat load definitely contributed as the initial cases appeared in temperatures around 35 C. The specific findings in our upcoming Canadian transportation code revision may lead to specific recommendations, but obviously we need to be extra careful handling, transporting and butchering cattle in the summer heat. Depending on distance travelled or number of cattle moved and sorted, perhaps a maximum temperature will be found that is safe. We also know that hide colour has a lot to do with heat stress and tolerable temperatures may go down as the percentage of black-hided cattle go up. A good percentage of the cattle we see today in Western Canada are black hided.
I was privy to a very descriptive video showing heat stress in a pen of mainly black-hided cattle. While the majority of the cattle were in the shade of a porosity fence and breathing heavily, the minority red and white cattle were up at the feed bunk eating. Of the few cattle I have treated for heat stress over the years, all have been black hided. Cattle handling, the distance to be loaded, the distance traveled and the related stress during movement all contribute to FCS.
These may all seem like common-sense observations, and they are, but until this specific syndrome appeared there was no reason to suspect we had a problem.
The researchers also performed tests to determine muscle enzyme levels in the blood. In affected cattle the levels get very high. It is the same with downer cattle as they attempt to rise or calves with white muscle disease.
Dr. Thomson and his group found that aggressive handling produced the same muscle lactate levels as running a seven or eight-minute mile or walking for about 20 minutes. We can all identify with this. If we run too far when we’re not used to it, our muscles can become extremely sore for a few days due to the buildup of lactic acid.
Feedlot cattle these days are getting bigger, and when they are in prime condition for butchering they are not athletic enough to be running around for any amount of time. In some large feedlots the home pen may be more than a mile from the load-out area and that had a bearing on the incidence of FCS, so changes may need to be made in lot design. It may require staged moving or more load-out areas.
It would be nice to have parameters that are easily measurable and tied in with temperature.
FCS was even more critical at the packing plants. Some common factors contributing to FCS at the plants were the time the cattle remained in the pens before slaughter and whether shade and cooling were available, particularly in areas with very hot climates. Cattle density in the pens was another factor. When holding pens get crowded the cattle cannot properly dissipate heat.
Animal handling practices and facilities were also looked at. Stress, exertion and rough handling can often be reduced by better facilities or better training of staff. Flooring was another factor. Some surfaces resulted in injuries to the feet.
In the U.S. discovering the causes of FCS has lead to a training and monitoring protocol termed the “FCS Stewardship Program.” The goal is to minimize or eliminate FCS by removing or reducing these risk factors across the industry.
Investigating all suspected cases should identify the areas that need improvement. Although the incidence of FCS may never have been as high in Canada as in the U.S. with our more temperate climate we still gets very hot summer days in southern areas of the country. So it makes sense to be aware of the potential ramifications of how we sort, process, load and transport cattle, especially with heavy marketweight, black-hided cattle on hot summer days.