How Castration Method and Age Affect Pain in Young Calves
This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the March 2018 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.
Canada’s Code of Practice for the Care and Handling of Beef Cattle requires that castration be performed by an experienced person who uses proper, clean, well-maintained equipment and accepted techniques. A producer is expected to seek guidance from their veterinarian on the optimum method and timing of castration, as well as the availability and advisability of pain control drugs for castrating beef cattle. Calves must be castrated as young as practically possible, and pain control is required when castrating bulls older than six months of age.
The requirement to use pain control in older calves was based on research demonstrating its effectiveness in feedlot bulls. A lot of information was also available regarding the use of pain drugs in baby dairy calves, but the beef producers and researchers on the Code committee felt that the vast differences in genetics, herd dynamics and familiarity with people meant that nursing beef calves may respond differently to castration than individually-housed dairy calves that had been weaned at birth. A research project funded by the Beef Science Cluster is helping to determine when pain control is beneficial in beef calves. As a first step, students working with Karen Schwartzkopf-Genswein (AAFC Lethbridge) and Ed Pajor (University of Calgary) examined how age and castration method affect acute and chronic pain in nursing beef calves (Journal of Animal Science 95:4352-4366 and 95:4367-4380).
What They Did:
Angus-cross bull calves were divided into three groups of 36 head. Groups were either castrated at 1-week (early April), 2-months (late May), or 4-months of age (early August). In each age group, 12 were knife-castrated, 12 were banded, and 12 were not castrated (control) but otherwise handled the same. The 1-week group was handled on the ground. A tip table was used for the 2-month group, and a hydraulic squeeze was used for the 4-month group. Scalpels were used for surgical castration at 1-week of age. A Newberry knife was used in older calves. Rubber rings were used for band castration in the 1-week and 2-month calves and a Callicrate bander was used in 4-month calves. Acute pain was evaluated using intensive physiological and behavioral pain measurements collected the day before castration, during castration, the hours immediately after and the first seven days after castration. Chronic pain and scrotal swelling and healing were assessed using weekly physiological and behavioral measurements collected over six to nine weeks, and weaning weights were compared.
What they Learned:
Acute pain in the first week after castration differed between methods. Regardless of age, behavioral responses at the time of castration were strongest for knife-castrated calves, intermediate for banded calves, and lowest for the controls. At 2- and 4-months, knife castrated calves kicked and bawled more than band or control calves. Signs of pain related to tail flicking, lying, standing and walking behavior were also more evident in surgical than band or control calves in the hours and days after castration at 2- or 4-months. Scrotal temperatures were lower in banded than in surgical or control calves at all ages.
Strictly speaking, the effect of castrating at different ages couldn’t be compared statistically, because the calves were castrated in different months, and because handling and castration techniques varied slightly between the age groups. Technicalities aside, only two or three pain indicators were apparent in either castrated group compared to control calves at 1-week. At 2-months, nine pain indicators were different in surgically castrated than control calves, while only two indicators were different in banded calves. At 4-months, 12 pain indicators were significantly higher in surgically castrated than control calves, and five were higher in banded calves.
Chronic pain beyond the first week of castration was not observed in calves castrated at 1-week or 2-months of age. Standing and lying behavior was significantly altered in the six to nine weeks following castration in calves banded at 4-months of age compared to control or surgically castrated calves.
Scrotal swelling and healing: There was less scrotal swelling and swelling went down sooner in surgically than band castrated calves at all ages. Scrotums healed at the same time for both methods in the 1-week and 2-month groups. Surgically castrated calves healed much sooner than banded calves in the 4-month group.
Performance: Initial weights at the time of castration were the same within each age group, but weaning weights were significantly lower for knife calves than with banded or control calves at 1-week (507 vs. 557lbs) and 4-months (518 vs. 535lbs) but not at 2-months of age (507lbs).
What it Means:
Castrate calves as young as practically possible. Banding caused less acute pain than surgical castration banding at 2-months, but more chronic pain at 4-months. This group is currently looking at the potential added benefit of providing pain relief drugs when castrating young calves.
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