All About Goat Testicles
It's what makes a buck a buck!
Reading Time: 4 minutes
Testicles make a buck a buck.
The testicles produce testosterone and sperm, and the correct testicle anatomy comprises two equal-sized testicles in a single scrotum. They should be firm and smooth. However, the epididymis’ tail can give the appearance of a lump at the testicle bottom or a dimpled scrotum. Visible faults include small testicles, abnormal testicles, undescended testicle(s), or an excessive split in the scrotum. Standards also advise avoiding bucks with testicles that are “too pendulous.” The carriage of the testicles should be between the flanks.
One of the most notable predictors of fertility is scrotal circumference, which correlates with sperm production. Scrotal circumference is measured at the widest point of the scrotum. According to the Merck Veterinary Manual, the scrotal circumference should be greater than 10 inches/25 centimeters in a mature standard buck (> 14 months). It can vary up to three centimeters by season, is the lowest outside of breeding season, peaking during rut, and lower during active breeding. It tends to be greatest from August to October.
Spermatogenesis is the continuous process of sperm development. Sperm are produced in the testes and enter the epididymis, where they are matured and stored in a dormant state until ejaculation. At ejaculation, they enter the vas deferens, which transports them to accessory glands in the abdomen. Sperm in a nonbreeding male expels in the urine.
Because of the time that it takes for sperm to mature, breeding young bucks is discouraged. Breed, environment, and genetics heavily influence when a buckling matures. If a kid does not achieve puberty by fall breeding season in seasonal breeders, it may be delayed until the following fall. Age, body weight, and nutrition also play important roles in the onset of puberty. While large breeds may be fertile at four to five months, they do not typically produce quality semen until they are eight months old. An immature buckling’s semen has a high proportion of sperm abnormalities and low sperm motility (Court, 1976).
A muscular sac called the scrotum encases the testicles and can relax and contract to adjust to temperatures. Sperm is sensitive to temperature, and fluctuation can result in infertility issues. The testes must remain at five to nine degrees F below body temperature for optimal function. When it is cold, the scrotum contracts to draw the testicles closer to the body and relaxes in the heat, allowing distance from the body. Fever, hot weather, and thick hair covering can contribute to testicular or seminal degeneration. The sperm in the ejaculate requires four to six weeks to mature. This is an important consideration when evaluating fertility or planning for breeding. Temperature anomalies during spermatogenesis will affect the buck’s performance.
Most registries in the United States discourage a split scrotum and have clear guidelines about the split’s’ extent, with no split as most desirable. This is not the case in other parts of the world. Sahelian goats raised in the Saharan and sub-Saharan region have split scrotums and split udders as breed distinctions. A study, often cited in favor of split scrotums, found that Beetal bucks with split scrotums showed better breeding efficiency in hot climates. That study only included a small sample of 15 bucks. (Singh, Manbir & Kaswan, Sandeep & Cheema, Ranjna & Singh, Yashpal & Sharma, Amit & Dash, Shakti, Kant. 2019). Some breeders caution that a split scrotum affects the mammary development and attachment of female offspring, but this has not been substantiated. The testicles and udder are entirely different anatomical structures, with only the location in common.
There are heritable genetic conditions that affect the testes. Cryptorchidism is when one or both testicles do not descend into the scrotum but are retained in the body cavity. In unilateral cryptorchidism (or mono-orchidism), where one testicle descends, the buck is still fertile. Bilateral cryptorchidism results in sterility. Another heritable abnormality is testicular hypoplasia, uni- or bilateral, characterized by small testicles, or testicles that fail to develop fully. Hypoplasia can also be a result of malnutrition or intersex/hermaphroditism.
Testicular disease is rare in goats. Caseous lymphadenitis, however, can affect the testicles and a buck’s fertility. The scrotum should be monitored for abnormalities, most typically swelling (orchitis) or lesions. Swelling can be caused by external injury, infection, or disease processes; heart failure can also cause the scrotum to swell. The epididymis is susceptible to bacterial infection called epididymitis. The scrotum’s most common issues are surface, including mange, mites, frostbite, and callusing. Insects such as ticks, thorns, and other foreign bodies can also lead to infection and abscesses.
If a buck is not desired for breeding, it can be castrated. Castration can be accomplished by removing the testicles through banding or surgical procedure. Burdizzo castration does not remove the testicles but crushes the spermatic cords, resulting in sterility and testicular atrophy. Castration will affect the testosterone levels in a male, which affects the development of secondary sex characteristics: libido, aggression, horn development, body mass, and self-urination.
Originally published in the 2021 special issue of Goat Journal — Goat Health from Head to Hoof Vol. 2 — and regularly vetted for accuracy.