Date of Graduation

12-2012

Document Type

Thesis

Degree Name

Master of Science in Animal Science (MS)

Degree Level

Graduate

Department

Animal Science

Advisor/Mentor

Powell, Jeremy G.

Committee Member

Gadberry, Shane

Second Committee Member

Thaxton, Yvonne V.

Third Committee Member

Kegley, Elizabeth B.

Keywords

Biological sciences; Analgesia; Behavior; Castration; Growth; Hematology; Meloxicam

Abstract

Angus-sired (n = 30) and Hereford-sired (n = 32) bull calves were assigned randomly to 1 of 4 treatments. Treatments were 1) surgical castration near birth, 2) oral administration of the analgesic meloxicam (1 mg/kg of body weight) followed by surgical castration near birth, 3) surgical castration at weaning, or 4) surgical castration at weaning with oral administration of the analgesic meloxicam (1 mg/kg of body weight). Data was recorded for behavior, hematology, and growth at birth and weaning. Calf standing and lying activity was monitored at both stages by recording x and y axis positions of a data logger accelerometer attached to the metatarsus of the right leg for 7 d. At birth, blood was collected on d 0 (birth), 1, 3, and 7 from a subset of calves, and post-weaning blood samples were collected on d 214 (weaning), 214 + 6 h, 215, 217, 221, and 228. Body weight was recorded on all calves on d 4, 33, 66, 116, 162, 199, and 214 (weaning). Body weight was recorded on all weaned calves on d 214 (weaning), 228, 246, and 270. Average daily gain did not differ between treatments (P ¡Ý 0.88) through weaning. The neutrophil to lymphocyte ratio at birth decreased with day (P < 0.0001). Following castration at birth, there were no differences in treatments for any of the three observed positions. Overall, post-weaning ADG was greater (P = 0.02) in steers compared to bulls castrated without meloxicam. At weaning the neutrophil to lymphocyte ratio displayed a d effect (P < 0.0001), with an increase at 6 h post castration, and then decreasing. Post-weaning behavior following castration resulted in steers spending the least proportion of time standing, and bulls castrated with analgesia tended to spend less time, numerically, lying on sternum compared to steers.

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