Vaccination Timing Does Not Affect Growth Performance but Enhances Antibody Titers in Previously Vaccinated Calves

The objective of this study was to evaluate the health, growth performance, and antibody titers of previously vaccinated newly weaned calves administered a respiratory and clostridial vaccine compared to no vaccination upon arrival. Single-sourced, newly weaned beef steers [n = 70; initial body weight (BW) = 254 ± 5.9 kg] were allotted to 10 pens (n = 5 pens/treatment; 7 steers/pen). Steers were blocked by BW in a randomized complete block design and assigned to one of two treatments: VAC (vaccinated for respiratory and clostridial species upon arrival) or NOVAC (not vaccinated upon arrival). Steers were individually weighed on d 0 (arrival), 1, 21, and 42 for growth performance measures. Whole blood samples were collected (n = 3 steers/pen) on d 1, 21, and 42 via jugular venipuncture for antibody titer responses. Depression scores (DS) of 0 (normal) to 4 (moribund) were recorded daily for each individual steer for 21 d. Dry matter intake as a percentage of BW tended (p = 0.07) to increase for the NOVAC group compared to the VAC group. No treatment × day interactions (p ≥ 0.50) were observed for DS or antibody titers. Growth performance was unaffected by vaccination but vaccinated calves had greater antibody titer responses throughout the 42 d study.