Water Restriction and Vaccination Impacts in Beef Calves

In the United States beef marketing process, calves are typically weaned from their dam and transported to a local auction market where they are purchased and transported to an order buying facility. They are subsequently transported again to a stocker or feedlot destination such that the potential exists for significant duration of water restriction. Upon feedlot arrival, stressed and dehydrated animals are processed, and this procedure typically includes administration of a modified-live virus (MLV) respiratory vaccine. The objective of this thesis was to review and evaluate the effect of water restriction on hematological, performance, and antibody parameters in beef calves administered a parenteral or intranasal MLV respiratory vaccine. A total of 60 clinically healthy, previously unvaccinated crossbred beef steer (n=28) and heifer (n=32) calves were assigned randomly to 1 of 6 treatments arranged in a 3  2 factorial. Three water restriction treatments (Factor A) were applied at the origin ranch: A1) Control, no water restriction at any time other than during transport (CON), A2) Acute, 48 h water restriction prior to transport (ACU), or A3) Chronic, alternating 24 h periods of water access and restriction over a 7-day period prior to transport (CHR). Upon feedlot arrival (day 0), 2 respiratory vaccine treatments were applied (Factor B): B1) parenteral administration of a pentavalent (IBRV, BVDV type 1 and 2, BRSV, PI3V) MLV respiratory vaccine (2mL subcutaneous; Express 5; SUB), or B2) intranasal administration of a trivalent (IBRV, BRSV, PI3V) MLV respiratory vaccine (1 mL/naris; Inforce 3; INT). Water restriction (ACU or CHR) increased hematocrit (P < 0.01) and transiently decreased BW (P < 0.01) and ADG (P = 0.03) from the time of water restriction treatment application through d 14. Transport caused an increase in white blood cells (WBC; day effect, P < 0.01); however, WBC decreased transiently after transport until day 7 (day effect, P < 0.01). The SUB group had a decreased total WBC count (P < 0.01) with specific decreases in lymphocytes (vaccine × day; P < 0.01) and monocytes (P = 0.01) and a greater body weight change from day 42 to 56 (P = 0.01) compared to INT. The ACU and CHR treatments had reduced ADG from day 0 to 14 compared to CON (P  0.04), regardless of vaccine treatment. The INT group tended to have greater overall serum BRSV- and IBRV-specific antibody titer concentrations (P  0.08) and BRSV-specific sIgA percent positivity index (vaccine × day; P < 0.01). There was a vaccine treatment  day interaction (P < 0.01) such that the INT groups had increased rectal temperature day 7 and 14 (P  0.04), greater BRSV-specific IgA on day 35, 42 and 56 (P  0.04), and greater BRSV and IBRV antibody titers on day 14 through 56 and day 21 through 35 respectively (P  0.04). These observations suggest greater antigenicity of INT when administered to stressed and water restricted animals. The stress of transport and dehydration may cause immune dysfunction that allows intranasally administered antigens to more effectively penetrate a compromised mucosal barrier in the naris. There was no apparent long-term effect of water restriction on antibody response in either vaccine group; however, the antibody responses to either vaccine in this study were low and may have been impacted by various lengths of water restriction experienced by all animals. Alternatively, the low antibody responses to vaccines evaluated in the current study could be due to other factors such as lack of a booster vaccination, genetic effects, or other individual animal variations.