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United States Department of Agriculture

Agricultural Research Service

Title: Impact of Fenbendazole on Turkey Semen Quality

Authors
item Bakst, Murray
item Long, Julie
item Kramer, Matthew

Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 13, 2006
Publication Date: April 5, 2006
Citation: Bakst, M.R., Long, J.A., Kramer, M.H. 2006. Impact of fenbendazole on turkey semen quality. Journal of Applied Poultry Research. 15:307-311.

Interpretive Summary: Fenbendazole (FBZ) is an anthelmintic recently approved to treat and control nematode infections in growing turkeys. Previous research has shown when administered to mature swine and cattle, semen quality and fertility was unaffected. While there are no side effects of FBZ administration to growing turkeys, we observed a decline in semen quality when used to treat mature turkeys. An experiment was designed to determine the effect of FBZ on spermatogenesis and semen quality. We discovered that while sperm viability and concentration was not significantly affected by FBZ, this drug significantly reduced the ability of sperm to swim through a viscous medium (mobility). We saw no differences in histological samples of testes between treated and control males. If a breeding flock of toms become infected with nematode parasites a flock manager has the following options: do not treat the toms; find an alternative to FBZ; treat the toms with FBZ and increase the sperm number and frequency of AI; or treat the toms with FBZ and secure semen from an uninfected tom flock.

Technical Abstract: Fenbendazole (FBZ) is an anthelmintic recently approved to treat and control nematode infections in growing turkeys. When administered to growing turkeys there are no detrimental side effects. However, when we used FBZ to treat nematodes in mature breeder toms, we observed a decrease in semen quality and a subsequent precipitous decline in fertility to less than 20% within 6 wk of administration. An experiment was designed to determine the impact of FBZ administration on aspects of spermatogenesis and semen quality. We discovered that while sperm viability and concentration was not significantly affected by FBZ, this drug significantly reduced sperm mobility. At the cellular level, FBZ binds to tubulin interfering with microtubule assembly. Based on testes histology and the immunocytochemical localization of tubulin in spermatids and mature sperm, FBZ had no impact on any aspect of spermatogenesis. We suggest that FBZ may be affecting sperm mobility by some molecular alteration of the sperm tail axoneme or midpiece, both tubulin containing structures. If a breeding flock of toms become infected with nematode parasites a flock manager has the following options: do not treat the toms; find an alternative to FBZ; treat the toms with FBZ and increase the sperm number and frequency of AI; or treat the toms with FBZ and secure semen from an uninfected tom flock.

Last Modified: 7/22/2014