Disease is a major concern for any livestock producer. In operations where offspring production is the primary focus, infections affecting fertility can result in a substantial decrease in both production and profitability. Such diseases are of great concern and demand top priority. One disease in particular, Caseous Lymphadenitis, is a growing concern for goat producers. Goats are usually prolific breeders; however, chronic illnesses can influence their reproductive performance. Animals infected with Caseous Lymphadenitis often display characteristic abscesses in the throat and neck region, fail to thrive, and may experience weight loss. These factors drastically affect the animal’s overall health, and contribute to a decrease in reproductive viability in male goats.
Caseous Lymphadenitis: Discussion
The bacteria Corynebacterium pseudotuberculosis causes the infectious disease, Caseous Lymphadenitis, (CL). Transmission of the infection usually occurs through contact with pus from abscesses, or from bacteria harbored in contaminated soil. (LeCuyer, Evermann, & Besser, 2016). This disease, previously known to cause chronic wasting, expresses itself in live goats through visible abscesses near the lymph node regions. Along with the presence of abscesses, yearling bucks infected with CL bacteria, experienced fevers and swollen lymph nodes (Mahmood et al., 2016). The effects of these symptoms on breeding bucks can cause pain, reduced feed intake and a subsequent increase in the loss of body condition. For the producer attempting to breed does with a recently infected buck, success may be limited.
The ability of a goat buck to produce offspring is dependent on several variables. Sperm quality, testosterone level, and scrotal circumference are all measurable factors that often directly correlate with male fertility. Yearling bucks infected with CL produced testosterone at a rate seven times lower than CL-free males, and exhibited a decreased scrotal circumference. From four to six weeks after the initial CL infection, the sperm concentration, motility, and semen wave pattern all decreased significantly in infected males. In addition, the sperm morphology rate, and the percentage of dead sperm present in the semen increased significantly during the four to eight weeks after infection (Mahmood et al., 2016). This research clearly demonstrates that CL significantly reduces the fertility of bucks. Since fertile breeding males are a necessity for any goat producer, it is important to take the necessary steps to prevent a CL outbreak, or manage an infection.
Because Corynebacterium pseudotuberculosis can remain viable in the soil for at least eight months, a CL infection can severely affect a producer in both the short and long term. The negative effect on buck fertility can be especially detrimental to the producer with a very limited number of breeding males. To protect the fertility of herd sires and the profitability of the operation, producers should be proactive in combatting CL. A vaccine against CL is available in some locations, but is highly regulated. Blood tests may be used to confirm the infection, and yield satisfactory results. Culling or separation of infected animals from the herd until the abscess heals is recommended (LeCuyer, et al., 2016). CL is not sexually transmitted, but close contact with infected animals increases the chance of transmission through pus or infected respiratory discharge. In order to ensure the health of bucks, producers should avoid using CL-free bucks on infected does.
Caseous Lymphadenitis is a serious disease affecting many goat producers. After infection, goat bucks experience a significant decrease in testosterone production, a decrease in sperm quality, and a reduction in scrotal circumference. While this may be to the nature of the wasting disease, rather than the direct influence of the bacteria, the results ultimately show a decrease in fertility among breeding males. While there is no cure for CL, proper culling, vaccination, if available, and testing of goat herds are major steps to ensuring herd health and buck fertility.
- Mahmood, Z. K., Jin, Z. A. M., Jesse, F. F., Saharee, A. A., Sabri, J., Yusoff, R., & Haron, A. W. (2016). Relationship between the Corynebacterium pseudotuberculosis, phospholipase D inoculation and the fertility characteristics of crossbred Boer bucks. Livestock Science, 191, 12-21.
- LeCuyer, T., Evermann, J., Besser, T., (2016). Caseous Lymphadenitis of Sheep and Goats.