Effects of flunixin meglumine administration on physiological and performance responses of transported feeder cattle.

The objective was to evaluate the effects of flunixin meglumine administration on physiological and performance responses of transported cattle during feedlot receiving. Forty-five Angus × Hereford steers were ranked by BW on d 0 and assigned to 1 of 3 treatments: 1) transport for 1,280 km in a commercial livestock trailer and administration of flunixin meglumine (1.1 mg/kg BW; intravenous) at loading (d 0) and unloading (d 1; FM), 2) transport for 1,280 km in a commercial livestock trailer and administration of 0.9% saline (0.022 mL/kg BW; intravenous) at loading (d 0) and unloading (d 1; TRANS), or 3) no transport and administration of 0.9% saline (0.022 mL/kg BW; intravenous) concurrently with loading (d 0) and unloading (d 1) of FM and TRANS cohorts (CON). Upon arrival and processing for treatment administration on d 1, steers within each treatment were ranked by BW and assigned to 15 feedlot pens (5 pens/treatment, 3 steers/pen). Full BW was recorded before (d -1 and 0) treatment application and at the end of experiment (d 28 and 29) for ADG calculation. Total DMI was evaluated daily from d 1 to 28. Blood samples were collected on d 0 (before treatment administration), 1 (after unloading but before treatment administration), 4, 7, 10, 14, 21, and 28. Body weight shrink from d 0 to 1 was less (P<0.01) in CON vs. FM and TRANS but similar (P=0.94) between TRANS and FM. Mean ADG was greater (P≤0.04) in CON vs. FM and TRANS but similar (P=0.69) between TRANS and FM. No treatment effects were detected on DMI, but CON had greater G:F vs. TRANS (P=0.08) and FM (P=0.02), whereas G:F was similar (P=0.68) between TRANS and FM. Mean plasma cortisol concentrations tended (P≤0.09) to be greater in TRANS vs. FM and CON but was similar (P=0.87) between CON and FM. Plasma NEFA concentrations were greater (P≤0.02) for TRANS and FM vs. CON on d 1 and greater (P≤0.04) for FM vs. TRANS and CON on d 4. Plasma ceruloplasmin concentrations were greater (P≤0.03) for TRANS vs. CON on d 1, 4, and 7, greater (P≤0.05) for TRANS vs. FM on d 4 and 7, and greater (P≤0.04) for FM vs. CON on d 1 and 4. Plasma haptoglobin concentrations were greater (P<0.01) for TRANS vs. CON and FM on d 1 and 4 and greater (P≤0.05) for FM vs. CON on d 1 and 4. In conclusion, flunixin meglumine reduced the cortisol and acute-phase protein responses elicited by road transport but did not improve receiving performance of feeder cattle.