Adverse effects of foot-and-mouth disease vaccine in dairy cattle

Foot-and-mouth disease represents an important barrier to the international commerce of animal products, potentially associated with significant economic losses. The systematic vaccination of bovines and buffaloes was fundamental for the eradication of this disease; however, the use of vaccines can lead to reactions at the application site. The objectives of this study were to evaluate the effects of the vaccination protocol to the production of dairy cows and to observe the occurrence of vaccinal reactions in the animals. At one property located in the municipality of Salvador do Sul, Rio Grande do Sul, 270 dairy cows were vaccinated against foot-and-mouth disease in May 2019. The vaccine was administered via a subcutaneous application using disposable syringes and needles for each animal. Inspection of the animals was performed before and 20 days after the vaccination to verify the presence of reactions to the vaccine. The study's sample was set by convenience, including 203 lactating animals with or without bovine somatotropin (BST) administration during the data collection period, which was limited to 20 days before and 20 days after the vaccination. Milk production data was obtained through SmartDairy (R) HerdMetrix (TM) software, tabulated in electronic spreadsheets using Microsoft Excel (R) and processed using the program SAS (R), considering a 5% significance level for mixed model statistical analysis. A total of 160 animals (78.82%) presented local lesions at the application site, even when the recommended vaccination practices were followed, suggesting that the high reaction power was provoked by the vaccinal components. In regards to milk production, a statistically significant (p<0.05) decrease of 0.30kg of milk per animal/day was observed in the average daily production in the 20 days post-vaccination. These results demonstrate the local and systemic effects caused by the foot-and-mouth disease vaccine, evidenced by reduced levels of milk production and the occurrence of vaccine reactions, implying significant economic losses.