Identifying lame animals seems an easy task. After all, lameness is when pain or discomfort causes a change in the way an animal walks. Cattle, however, are stoic creatures and might not show much until the pain is severe. And that has made it a challenge to understand the degree of lameness in feedlots.
Previous research looked at the causes of lameness in feedlots, from injuries to infectious disease and treatments. Our studies provide a starting point for developing effective treatment protocols for lameness, by developing an understanding of the true prevalence in feedlots and the characteristics of these cases.
In previous research lameness was reported in 15 to 30 per cent of animals at slaughter but the potential for rejection of downers at slaughter likely causes such audits to under represent the true prevalence of lameness in feedlots.
In the summer of 2010, we gathered preliminary data on lameness in the chronic/hospital pens at three different feedlots near Lethbridge. Every two weeks for three months researchers and two independent observers gait scored cattle, noting the limb involved and the severity of any apparent lameness. Blood profiles, weight and temperature of every animal in the chronic pen were collected along with their treatment history, days on feed and the feedlot s diagnosis that sent them to the sick pen. Every animal in a chronic pen was evaluated, unless they were non-ambulatory.
For our purposes it was agreed that chronic pens were meant to function as housing for ill animals whether short-or long-term and all such pens at the feedlots were evaluated.
Across all three feedlots, a total of 275 animals were observed in the chronic pens seven times over three months. The prevalence of lameness in the chronic pens varied between 32.8 and 52.8 per cent for an overall average of 37 per cent. In 77.5 per cent of these cases it was a rear leg that was affected. According to the pen checker s diagnoses, lameness accounted for 37.4 per cent of animals in the chronic pen, respiratory disease for 35.7 per cent, and respiratory disease in combination with lameness, 10.9 per cent. The other 16 per cent were in for various conditions such as bloat, vaginal prolapse, pinkeye and nervous disease.
This short-term study indicates that under 2010 conditions lameness represents a relatively high proportion of chronic pen cases The results show a much higher prevalence for lameness than found in one U.S. study that linked lameness to 16 per cent of health problems and five per cent of deaths.
The spring and summer of 2010 was a particularly wet one in southern Alberta so sloppy pen conditions may have contributed to this higher incidence. Additional data would be needed to better assess the impact of seasonal variation and how pen condition affects the risk of lameness in feedlots.
Treatment histories indicated lame animals were treated less than those with other pathologies. This is likely due to the presence of more aggressive treatment protocols being set for respiratory disease and the other category. For some types of lameness, especially severe cases, there may not be a treatment option that can restore the animal to a healthy state. This lack of a strategy for handling these cases becomes an issue for these animals, who by definition are experiencing pain and discomfort.
Animals cut out for lameness in conjunction with respiratory disease were given a first treatment an average of 17.3 days on feed compared to 74.2 days in cattle pulled for lameness alone. This may reflect the stoic nature of cattle and the challenge for pen riders in identifying cases before the lameness becomes severe. Reviews of lameness in feedlot cattle in the U.S. have found that significant amounts of bovine respiratory disease (BRD) generally precede signs of lameness and suggest a pneumonia-arthritis syndrome as the cause. It is plausible that the syndrome is involved in the earlier treatment of lame animals with respiratory issues in the current study.
Cattle scored as lame by researchers gained an average of 7.5 kilograms less during the two weeks between observations than the other cattle in the chronic pens. Analysis of the same biweekly gain using the feedlot s diagnoses to classify animals showed no difference in performance between lame and non-lame cattle. Studies in dairy cattle have consistently associated lameness with reduced feed intake and lower production.
Our data indicates lameness is a prevalent issue in chronic pens, posing a welfare and chronic challenge to feedlot managers. Regulations and enforcement on the transportation of lame animals is becoming stricter, affecting the ability to market these animals and salvage some carcass value. Developing better methods for identifying lameness, risk factors and treatment protocols holds the promise of reduced suffering for the animals and a better return to the feedlot.
ChristywasamemberofaresearchteamledbyKarenSchwartzkopf- GensweinoftheLethbridgeresearchcentre.Othermembers oftheteaminvolvedinthisstudyare:ElenaTessitore,Eugene Janzen,EdPajor,GiulioCozzi.