Effects of different vaccination schedules prior to dry-off on systemic inflammation, immunity, and subsequent performance of dairy cows

This study aimed to evaluate the effects of different vaccination schedules before dry-off (DO) on systemic inflammation and immunity during the early dry period and performance in the subsequent lactation in primiparous (PRIM) and multiparous (MULT) Holstein dairy cows in a commercial dairy farm. Farm standard operating procedure included administering vaccines (Enviracor J-5, ScourGuard 4KC, Ultrabac 7/Somubac, Zoetis) 2 d before DO and relocating to pasture where cows were fed only hay and milked once per day until DO. Late-lactation cows were assigned to either the control (CON; vaccination 2 d before DO, n = 174) or early vaccination (EV; vaccination 11 d before DO, n = 154) group based on the last digit (even/odd) of their ear tag. This pseudorandomization approach was adopted to facilitate the treatment administration by farm personnel. Cows in CON and EV groups had similar parity, DIM, milk yield before enrollment, and test-day SCC before DO, suggesting both groups were balanced, and no treatment assignment bias was presented. Blood was sampled from a subset of cows (n = 38/treatment) on d -11, -9, -7, -2, +1, +4, +8, +11 relative to dry-off (RTD) to analyze cortisol, haptoglobin, glucose, nonesterified fatty acids, and BHB. Day +1 RTD represents the day of DO. Peripheral blood mononuclear cells (PBMC) were isolated on d +4 RTD and stimulated with LPS or concanavalin A (ConA) to assess cytokine production. Cows in the EV group had greater circulating haptoglobin on d -9 and -7 RTD, whereas CON cows had greater circulating haptoglobin on d +1 and +4 RTD. These suggest that relative to CON, EV shifts the inflammatory response caused by vaccination to late lactation, lowering inflammation in the early dry period. Regardless of the treatment or parity, serum cortisol concentrations significantly increased on d +1 RTD before the last milking. Regardless of parity, compared with EV cows, PBMC collected on d +4 RTD from CON cows exhibited increased production of proinflammatory cytokines and chemokines following either LPS or ConA stimulation. Giving vaccination earlier reduced daily milk yield before DO, with daily reductions ranging from 4.1% to 11.6% over a 9-d period after vaccination in MULT cows and 4.1% to 7.1% reductions within 4 d after vaccination in PRIM cows. Due to reduced milking frequency and feed restriction, all cows experienced a sharp decline in milk yield after d -2 RTD. In the subsequent lactation, milk yield, ECM, FCM, milk fat content and yield, and milk protein yield were greater or tended to be greater in EV-MULT cows than CON-MULT cows, whereas no differences were observed in PRIM cows. In conclusion, administering vaccines 11 d before DO decreased milk yield before DO, lowered systemic inflammation in the early dry period, and improved subsequent lactation performance in MULT cows.