Bob Springer PAg , Regional Livestock Specialist, Saskatchewan Ministry of Agriculture, Swift Current
Lameness can be a very significant economic factor for cattle operations by impacting animal performance and reproductive efficiency of both cows and bulls. The greatest impact is on bull performance and fertility. Bulls account for 50 per cent of the genetics and pregnancy rates on 25-40 cows in each herd and reproductive performance is the most important factor influencing profitability in the cow-calf business.
Looking at culling records on over 10,500 PFRA Pasture bulls used since 1983, lameness was the number one reason for bulls to be culled, accounting for 41 per cent of the culled bulls during this period.
I recently attended the third International Symposium on Cattle Welfare in Saskatoon where Dr. Chris Clark, from the Western College of Veterinary medicine gave a very interesting talk on lameness in cattle. His research suggests that, contrary to producer perception, a large proportion of lameness that occurs in cattle on pasture is not Foot Rot.
There are several other causes of lower foot lameness including sole abscesses, laminitis and sand cracks that will not respond to antibiotics. Foot Rot is a very specific foot infection that can be visually identified by a break in the skin between the claws and swelling that causes the claws to spread apart. It is caused by a bacterium that is very susceptible to antibiotics. Dr. Clark says that if the lameness does not improve within 36 hours following administration of an antibiotic, then you know that the problem is not Foot Rot.
Lameness can be very common in some years and can result in large economic losses for your operation. Lame cows can have trouble eating enough to maintain body weight on pasture and lame bulls may not be able to breed during the breeding season, resulting in reduced pregnancy rates in the cow herd. Dr. Clark indicated that the effectiveness of the vaccine available for Foot Rot is not well known but its use might be cost effective in bulls to reduce the incidence and severity of Foot Rot during the breeding season.
Dr. Clark’s take-home message: If you have an animal that is lame and you suspect Foot Rot and it’s not practical to examine the foot to look for a lesion between the claws, the best approach is to treat it with an antibiotic. If the lameness isn’t reduced within 36 hours, you know the cause isn’t Foot Rot and further investigation by a veterinarian is required. Quick treatment of lameness is important not only for the welfare of your animals but it will help to prevent future economic losses in your herd.
If you do have lame bulls, not only will they probably not be able to physically breed cows, their semen quality will very likely be reduced by the stress of the infection. Dr. Al Barth with the Western College of Veterinary Medicine large animal clinic has been semen testing bulls for many years throughout the province. He has found that not all bulls respond to stress the same, however, there is a good chance a bull with a hot swollen lame foot will experience a decline in semen quality. The longer to recovery, the more semen quality is depressed. Usually semen quality bottoms out 3.5 weeks after the onset of a severe stress. If the problem is cured fairly soon, say in a week, semen quality will be back to normal in about six weeks.
Dr. Barth’s Take-home message: producers need to be aware that lame bulls, even after they have recovered, may not have good semen quality for several weeks...essentially producers need to assume this bull is not breeding any cows and should replace him with a new bull for the remainder of the breeding season to avoid reduction in pregnancy rates.