By Dr. Jim Neel
Did your herd bull receive any concern during the long cold winter we have experienced? Probably most of the concerns were directed toward the cow herd and calves. However, the long cold winter we experienced may have led to several negative effects on the bull that could severely reduce his reproductive potential. These range from frostbite on the bull’s scrotum, excess loss of body condition, and perhaps injuries to the feet and legs depending on the condition of the frozen surfaces they were walking on.
Under normal winters, with sufficient care, the effects of cold weather would be less of a problem. However, with the extremely cold weather this year, bulls have been exposed to conditions with greater risk of frostbite and cold injury to the scrotum and testicles that can cause subfertility or in some cases, infertility.
In cold weather sperm quality is reduced, and the colder it gets the more quality reduction occurs. Bulls with larger, hanging scrotums are be more susceptible to being sub fertile or possibly, even sterile in cold conditions. These bulls would have a problem “drawing” their testicles up close to their body to keep them warm.
Both cold and hot weather can interfere with the spermatogenesis process and reduce reproductive potential.
Check the bulls’ scrotum for scabs; these would probably be found on the lower part of the scrotum. The presence of “no scab” is not an assurance that the reproductive potential is not negatively affected. If frostbite and or cold injury is a concern, the bull should have a Breeding Soundness Examination (BSE) 45 days or so after the injury. Check with a local bovine veterinarian and discuss the possibility of “frost bite” and arrange to have a BSE done on the bulls.
A BSE prior to the breeding season has always been a good practice and may be even more important this year. An exam should include an evaluation of the bull’s reproductive tract, semen volume and quality, as well as the bull’s structural soundness and overall physical condition.
Observe the bulls for lameness, as frozen, slippery and sometimes sharp edged ground conditions can lead to lameness that will affect their ability to breed cows.
Did they come through the winter in decent physical condition? Or, did they end up thinner than you would like due to the cold weather energy requirements causing them to burn more calories to stay warm? Ideally bulls should have a similar Body Condition Score (BCS) to that of replacement heifers: from a 5 to 6.5. Top performing bulls will be busy and lose weight during the breeding season so they need to be in adequate condition before breeding begins. Also remember young bulls are still growing and may need extra feed during the breeding season.
During the pre-breeding period bulls should physically and nutritionally prepared for the work they have ahead of them. During the peak of breeding season bulls will need the physical stamina to cover many miles in one day. Just like with people, reaching this level of fitness won’t happen overnight. Providing a 1-2 acre lot during the pre-breeding period will go a long ways in building a bull’s stamina.
So, take a good look at your bulls to see how they made it through winter. Now is the time to evaluate them, so that you have sufficient time to put them on a pre-breeding program to have them ready to go when the time comes, or have time to find replacements if needed.
Source:uwex.edu