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Title: Effect of surgical castration with or without oral meloxicam on the acute inflammatory response in yearling beef bulls

item ROBERTS, SHELBY - West Texas A & M University
item HUGHES, HEATHER - West Texas A & M University
item Sanchez, Nicole
item Carroll, Jeffery - Jeff Carroll
item POWELL, JEREMY - University Of Arkansas
item HUBBELL, DON - University Of Arkansas
item RICHESON, JOHN - West Texas A & M University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2015
Publication Date: 8/6/2015
Citation: Roberts, S.L., Hughes, H.D., Sanchez, N.C., Carroll, J.A., Powell, J.G., Hubbell, D.S., Richeson, J.T. 2015. Effect of surgical castration with or without oral meloxicam on the acute inflammatory response in yearling beef bulls. Journal of Animal Science. 93:4123-4131.

Interpretive Summary: This research represents a collaborative effort of scientists from West Texas A&M University, the Livestock Issues Research Unit, and the University of Arkansas to determine whether treatment of bulls with the analgesic meloxicam would alter the stress and immune responses to surgical castration. Castration of beef bulls is stressful, yet a common management practice within the United States. Physical castration has been demonstrated to negatively affect performance, increase disease risk, and alter behavior and physiology to suggest pain. Therefore, this study was designed to elucidate the effect of surgical castration on the acute inflammatory and immune responses, and determine if concurrent oral administration of meloxicam would alter these responses. The results from this study demonstrate that administration of meloxicam was able to diminish the cortisol response and reduce the magnitude of the inflammatory response. Specifically, the acute phase protein haptoglobin and certain peripheral blood leukocytes were reduced in bulls administered meloxicam. Yet, there was a delayed and extended febrile response in meloxicam-treated bulls. Further research is needed to determine whether administration of meloxicam may impede convalescence following surgical castration. These data will be of interest to scientists in the field of stress physiology, as well as cattle producers, and can be used to modify management procedures in order to reduce pain and stress associated with the castration procedure.

Technical Abstract: Pain management and welfare are increasingly prevalent concerns within animal agriculture. Analgesics may alleviate pain and inflammation associated with castration of beef cattle. This study was conducted to elucidate the effects of surgical castration on the acute inflammatory response and immunomodulation, and whether concurrent oral administration of meloxicam (1 mg/kg BW) would alter these responses. On d -1, crossbred bull calves (n=30; initial BW = 227.4 ± 10.3 kg) were fitted with indwelling jugular cannulas and rectal temperature (RT) recording devices, placed into individual stanchions, and assigned randomly to 1 of 3 treatments. Treatment application occurred at h 0 and consisted of: 1) intact bulls with sham castration (CON), 2) surgical castration (CAS), and 3) surgical castration with oral meloxicam (MEL). Blood samples were collected at 0.5-h intervals from h -2 to 4 h, 1.0-h intervals from h 4 to 8 h, and 12-h intervals from h 12 to 72 h. Serum was analyzed for cortisol and haptoglobin (Hp) concentrations using ELISA. Whole blood was analyzed for complete blood counts at -2, 0, 2, 4, 6, 8, 12, 24, 36, 48, 60, and 72 h, and RT was recorded in 5-minute intervals. Post-castration RT was greatest for MEL (39.04), intermediate for CAS (38.99), and least for CON (38.93°C; P = 0.01). Serum cortisol was increased (P < 0.001) for CAS (12.3) and MEL (11.3) compared to CON (6.7 ng/mL) during the post-castration period. At 0.5 and 1.5 h, cortisol concentration was greater in CAS and MEL than CON; whereas, at 2 and 2.5 h cortisol concentration was greatest for CAS, intermediate for MEL , and least for CON (trt x time; P < 0.001). Total white blood cell (P = 0.04), lymphocyte (P = 0.02) and monocyte (P = 0.002) counts were greatest for CAS, intermediate for MEL and least for CON. Administration of MEL reduced (P = 0.002) eosinophil counts during the post-castration period when compared to CON and CAS. The change in serum Hp, relative to baseline values, was reduced for MEL at 36 (P < 0.01) and 60 h (P = 0.03), and the overall Hp concentration was least for MEL (P < 0.001). Oral administration of meloxicam at the time of castration reduced the acute inflammatory response in castrates, as evidenced by a reduction in Hp and certain leukocyte concentrations, it also caused a delayed increase in RT. Further research is needed to determine if this reduced acute inflammatory response would equate to improved health and/or performance post-castration.