Effects of 2 commercially-available 9-way killed vaccines on milk production and rectal temperature in Holstein-Friesian dairy cows

Veterinarians and farmers employing multivalent killed vaccines in lactatin g dairy cows have reported transient losses in milk production. Few studies have quantified this loss. In this report, effects of 2 commercially avail able 9-way vaccines on milk production and rectal temperature are examined. Repeated measures analyses of variance were used to compare changes in mil k production and rectal temperature over time between treatment groups. The re was a significant (P < 0.01) interaction among treatment and time when c omparing vaccine- and placebo-treated animals. When pretreatment milk produ ction (or days in milk) and pretreatment rectal temperature were considered , respectively, as covariates, a significant (P < 0.05) depression of milk production and a significant (P < 0.05) increase in rectal temperature were observed one day following injection. These effects were small and short-l ived. The stage of lactation, level of milk production, and choice of produ ct may be used as decision-making tools to decrease milk production losses in vaccine-candidate cows.