Introduction
Artificial insemination (AI) is widely used in the global cattle industry to enhance genetic potential and streamline breeding. However, AI also carries the risk of introducing bacterial pathogens to herds. To mitigate this, antibiotics are added to semen extenders to inhibit bacterial growth and ensure reproductive health. The most commonly used antibiotic combination—Gentamicin, Tylosin, Lincomycin, and Spectinomycin (GTLS)—has been in place since 1988. While it has proven effective against some pathogens, concerns have arisen regarding its ability to control Mycoplasmopsis bovis (M. bovis), a significant cause of bovine reproductive and respiratory diseases.
Study Overview
A recent study examined the efficacy of the GTLS antibiotic cocktail in controlling key bacterial pathogens in bovine semen. Researchers spiked semen samples with various bacteria and analyzed their survival rates after antibiotic treatment. The study focused on five major pathogens known to impact cattle reproduction:
- Histophilus somni
- Campylobacter fetus subspecies venerealis
- Mycoplasmopsis bovis
- Ureaplasma diversum
- Leptospira interrogans
The findings confirmed that GTLS effectively killed H. somni, C. fetus subspecies venerealis, U. diversum, and L. interrogans. However, it only inhibited M. bovis rather than eliminating it, raising concerns about its continued effectiveness.
Implications for the Industry
The study’s results highlight the need to reassess current AI practices, particularly in light of increasing antimicrobial resistance (AMR). While GTLS has been a longstanding standard, its limitations against M. bovis suggest that alternative antimicrobial strategies may be necessary to ensure the safety of bovine reproductive practices.
Moving forward, further research and potential updates to industry guidelines may be required to enhance AI biosecurity measures and protect herd health globally.
For the full study, visit: https://www.journalofdairyscience.org/article/S0022-0302(25)00067-0/fulltext
