Breeding Soundness Exams (BSE) for bulls are an important investment. When everything appears normal, you should do exams on all bulls in your herd, regardless of age or past history, 30 to 60 days before the onset of breeding season. The truth is that while there are very few sterile bulls, there are a lot of poorly fertile bulls, one count suggests in excess of 20%, and it is these poor breeders that the exam is designed to locate and eliminate. Unfortunately many poorly fertile bulls are not identified until after the end of breeding season when a high percentage of cows fail to become pregnant.
The BSE will start with a thorough physical exam. A breeding bull is only as good as his general health. Special attention will be paid to feet and legs, with the veterinarian watching the bull move. The bull can’t detect cows in heat if he can’t keep up with the herd as it moves around the pasture, and he can’t breed cows unless his hind limbs are strong enough to carry his weight. Bulls locate cows in heat by sight rather than by smell so he has to have normal eyes to be effective. The bull should receive a body condition score of at least 5, with 6 being better. A bull with a body condition score of 4 may look acceptable now, but he is likely to get thin enough towards the end of the breeding season to affect his breeding performance. His teeth should be examined also. If he doesn’t have enough teeth left to maintain his body condition at a time of hard work he will not be acceptable. A normal sheath should point at the ground between the bull’s front feet. If it is excessively pendulous or points straight down the bull will be predisposed to injury.
It is important that the bull’s penis be fully extended so that it can be examined. Several conditions may involve the penis. Persistent frenulum is an attachment of the penis to the sheath that prevents extension. It can be easily corrected, but since it is inherited, the bull probably shouldn’t be used as a breeder if his sons are to be saved as prospective sires. Other less common maladies of the penis or sheath may be discovered by the veterinarian during the breeding soundness exam. Both testicles should be palpated. Asymmetry might suggest inflammation, degeneration, neoplasia, or hernia. The measure of scrotal circumference is part of the BSE. Scrotal circumference varies with the breed and age of a bull. The most significant testicular growth in a bull occurs from the ages of 6 to 36 months. Selection of potential herd sires is often done at 12 to 14 months and is based on scrotal circumference. Various breed associations and bull sale organizations have developed guidelines for the minimum SC of bulls at different ages. See Cow Calf Corner Library for more about scrotal circumference.
Rectal palpation is required to examine the accessory sex glands, which are located inside the pelvis. The prostrate, ampulae, and seminal vesicles all have roles to play in the storage and delivery of sperm cells. Softness or swelling of any of these glands may indicate a breeding problem.
The semen evaluation portion of the BSE consists of obtaining a sample and examining it microscopically. The best way to obtain a sample is with the use of a teaser cow and an artificial vagina. Bulls usually must be trained to this procedure, however, so it is not practical for doing a BSE on a range bull. Electro-ejaculation works well also, and newer ejaculators are much improved. The newer models cause less stimulation to the nerves of the hind limb, making collection less stressful to the bull. Computerized controls apply only as much stimulation as is required in an increasing pattern. This eliminates operator error and leaves the technician with both hands free to collect the sample. Once the sample is obtained care must be taken to keep it warm until it can be examined and it should be checked as soon as possible, as sperm cells are very subject to cold shock. Too much exposure to the atmosphere, especially on a cold day, can make a good bull look bad. The Society for Theriogenololgy has established standard thresholds for acceptable levels. The bull must exhibit 30% or greater cell motility, 70% or greater normal morphology of cells, a scrotal circumference acceptable for his breed and age, and a satisfactory physical and reproductive tract examination. Bulls must pass all four criteria to pass the BSE. Bulls are considered acceptable (should be a good breeder), deferred (did not pass but problem may be resolved over time), and unsatisfactory (did not pass and has a non-resolvable problem).
In some cases bull breeding soundness exams can prevent the catastrophic loss of a calf crop. In all cases they can increase profitability by producing more pounds of calves to walk up the ramp on shipping day, and by cutting unnecessary purchase and maintenance costs of bulls. Today’s production costs are increasing steadily, and producers are trying to stretch limited income to cover these costs. Bull breeding soundness exams are low cost inputs with big returns. Though it varies from area to area, most veterinarians charge between $25 and $40 per bull for breeding soundness exams. One figure computed for cow herds nation-wide suggests that breeding soundness exams can increase cow herd income by $17.00 per cow. Isn’t it time to quit leaving these dollars lying on the table?
Source: Dave Sparks, DVM, Area Food-Animal Quality and Health Specialist