Location: Livestock Issues Research
Project Number: 3096-32000-008-017-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Jul 9, 2017
End Date: Jul 9, 2022
The objective of this study is to evaluate the effects of timing of administration of topical flunixin meglumine on the innate immunological and acute phase responses of feedlot cattle during a viral-bacterial respiratory disease challenge.
Beef calves (n=32 heifers; 8/treatment) will be transported to the USDA-ARS Livestock Issues Research Unit and allowed to rest in pens overnight. The next morning, calves will be weighed, and randomized to 1 of 4 treatments through a working chute using a pre-prepared chute order such that 8 animals are randomly assigned to each treatment: 1) Topical flunixin meglumine administered on-arrival (ARR); 2) Topical flunixin meglumine administered 72 hours after arrival at the time of viral challenge (VIR); 3) Topical flunixin meglumine administered 144 hours after arrival at the time of bacterial challenge (BAC); and 4) Positive control: No flunixin meglumine administered (CON). Calves in ARR treatment will be administered topical flunixin meglumine at this time. A blood sample will be collected via jugular venipuncture, an indwelling temperature recording device will be inserted, and a fecal sample will be obtained for fecal egg count determination. Calves will subsequently be penned by treatment to prevent licking and contact transfer of topical treatment while housed in outdoor, fully covered, dirt floor pens for 72 hours. Sickness scores will be collected daily while calves are in outdoor pens. After 72 hours, calves will be weighed, and administered 1x108 PFU of BHV-1 using an intra-nasal atomizer in each nostril. At this time, a Whisper score will be collected (if employees are trained prior to study initiation), a nasal swab will be obtained along with whole blood and blood for serum via jugular venipuncture. A nasal lesion score will be determined for each animal. Calves in the VIR treatment will be administered topical flunixin meglumine, and calves will be returned to outdoor pens and penned according to treatment. After 72 hours, calves will be returned to the working chute, a Whisper score will be collected, weighed, and then restrained using a halter. A jugular catheter will be inserted and whole blood and blood for serum will be collected, a nasal lesion score will be recorded, and 100 mL of 1x107 CFU of M. haemolytica will be administered intra-tracheally. Calves in the BAC treatment will be administered topical flunixin meglumine, and all calves will be moved into individual stalls in an indoor, environmentally-controlled barn. Sickness scores will be determined in the stalls every 12h until 72h. Whole blood from all calves will be collected via jugular catheter every 2h for 8h for CBC analysis, and every 12h until 72h. Blood for serum will be collected every hour for the first 8h and every subsequent 12h until 72h. Sickness scores will be recorded every 12 h, and any animals with a sickness score of 3.5 or greater will be administered Zuprevo and removed from the study. Jugular catheters and temperature loggers will be removed 72h after M. haemolytica challenge, a Whisper score will be collected, whole blood and blood for serum will be collected via jugular venipuncture, cattle will be treated with Zuprevo, and then returned to the outdoor pens. Body weights and nasal lesion scores will be collected 168h and 360h (7 and 15 days) following M. haemolytica challenge. Nasal swabs to determine viral shedding will be collected at d 15.