A good buck is an integral part of any goat breeder’s success. There are many different things to look at such as bloodlines, conformation, and production records. However, none of these things are important if the buck of choice cannot impregnate a doe due to possible infertility problems.
Most buck infertility problems can be traced back to underlying causes. If a buck is too young or too old he may have a low sperm count due to immaturity or overuse. It can take up to six weeks for sperm levels to rise to normal rates. Nutrition plays an important role in the fertility of goats. A fat buck will not be able to breed as well as a goat that has been kept on a good nutritional diet. Likewise an extremely skinny goat might have a low conception rate due to problems related to his diet.
In addition to nutrition there are other things to keep in mind. A buck might experience detrimental stress if moved around at breeding time. An injury can also have negative effects if the buck has hurt his back or his rear legs and is in pain when he mounts a doe. He may also have an undetected illness.
Nutritional, stress, and injury problems can be corrected, but determining sperm counts requires help from a vet. This is a surprisingly easy and informational process and checking a buck’s fertility does not cost much. A phone call to the vet, an office visit with the buck in question, and all concerns can be quieted.
During a single office visit the vet can find out a lot about the buck. First a routine exam should be done. This insures that the buck is in good health, not anemic, or running a fever. An examination of the scrotum and surrounding area is done; the scrotum area is palpated to ensure that there are two testicles. There should not be any lumps or tears and the scrotum should have a large circumference.
The preferred actual size seems to vary from vet to vet and breeder to breeder, but what seems to be important is that the scrotum appears large for the animal in question. The testicles need to be of equal size and there should not be a split in the scrotum. Some breed standards allow for an inch split, but it is seems to be much better to have no split.
There is a direct correlation between the size of the scrotum and fertility in the sire’s daughters. In other words, the larger the buck’s scrotum, the more fertile his daughters should be.
After the vet completes an initial examination, a semen sample must be collected; this can be the longest part of the exam. There are three different methods that may be used to achieve this. The first is called the artificial vagina. This is a device that is lubricated and placed in front of the buck. It is usually attached to a teaser animal and the buck must ejaculate into it. The second is called digital manipulation. The animal is manually manipulated and ejaculates into a collection vial. The third way is referred to as electro-ejaculation. This method applies a series of short low voltage pulses to the pelvic nerves, causing semen ejaculation. This is collected in a collection vial.
After the vet has collected a semen sample, a microscope is often used for evaluation. Some of the things considered are the volume of the semen, concentration, motility, and the rate of abnormal sperm.
The semen sample must be also be observed visually to determine if there are any abnormalities such as lumps or flakes. The presence of these means there is something wrong with the buck.
A hemacytometer is used to count sperm. The hemacytometer is a glass slide with a graph etched into it. It helps determine how many sperm are in an area, which helps determine the rate of sperm in an ejaculation. The desired rate is 5.5 billion per ml.
A vet can also determine an abnormal white blood cell count while doing this exam. The vet will also determine the rate of live sperm vs. dead sperm. A lot of dead sperm or sperm swimming in circles is not a good thing.
Research shows that the more often a buck ejaculates, the weaker his semen becomes. This is why it is strongly recommended that a young buck not be overused. If his sperm count was low, test it again in four to six weeks. A buck that shows signs of a high sperm count but still has problems settling any does will need further examination to see if he is having difficulties mounting or finishing. Each of these problems would need to be addressed individually.
There are a few other things to keep in mind when evaluating a buck’s breeding ability. A buck with a split scrotum can still impregnate a doe. However, this is a character flaw and something that may not be wise to pass along. A buck that has only one testicle or a set of mismatched testicles can still impregnate a doe; they need to be kept in a buck pen away from does that may accidentally get bred. A buck that tested sterile or had a low sperm count can and often will recover, which means unless sure that buck is a wether with "no strings attached," keep him in a buck pen.
Just because a buck does not impregnate a doe the first year he is around, does not mean he is not a good buck. The same goes for any buck with fertility problems. There is usually an underlying cause of infertility. Consulting a goat-knowledgeable vet and identifying that cause is the first step towards a successful breeding season.
This article was written based on the author’s experience/consultation with licensed veterinary personnel at Town and Country Animal Clinic, Newton, KS.