Do foot and mouth disease vaccines affect bovine bull fertility? A systematic review and meta-analysis

Abstract

• FMD vaccination may trigger fever and oxidative stress, leading to sperm cell damage, reduced sperm quality, and increased sperm abnormalities in bulls • Despite transient changes in sperm parameters, regular vaccination is essential for preventing infectious diseases in breeding bulls. Foot-and-mouth disease (FMD) is a highly contagious, reportable, and economically devastating disease of cattle and other cloven-hoofed animals. Vaccination against FMD remains the mainstay control strategy in many countries prone to the disease. Evidence shows that vaccinations against FMD could have negative consequences on bull fertility; however, the existence of that threat has received little attention amongst researchers and governments, probably due to weaker evidence from individual reports. This review aimed to systematically gather available evidence from different studies and meta-analyse the data to provide evidence-based pooled estimates of the effects of FMD vaccines on key indicators of bull fertility. To that end, we gathered and analysed published data from PubMed, Web of Science, and Google Scholar to determine the pooled estimates or descriptive synthesis of the effects of FMD vaccine on semen quality, measured before and after administration. A total of 9 articles were included in the meta-analysis, from which semen parameters were pooled using the inverse variance method, while 4 additional studies were synthesized descriptively. The weighted mean difference (WMD) was used to measure the effect sizes, with statistical significance set at p < 0.05. Although the FMD vaccination showed no effect on sperm volume between 7-14 days post-vaccination, it significantly increased sperm volume between 28-35 days post-vaccination (WMD 0.04ml, 95% CI 0.00, 0.08, p = 0.03. While the findings from the narrative synthesis present contrasting outcomes, they collectively suggest that vaccination may influence sperm quality in bovine bulls through physiological pathways potentially involving transient hyperthermia and oxidative stress.