What follows is a basic review of the castration of cattle. Associated welfare issues have been evaluated and are described using physiologic, behavioral, and production indices.

Castration
Castration is the removal of the testes, or testicles, of male animals. Various methods have been used to castrate cattle. Physical methods result in the removal, irreversible damage, or destruction of the testes, and include application of elastrator bands or rubber rings; the use of the Burdizzo castration clamp; and excision, using a castration knife or open, closed, or modified closed surgical techniques. Elastrator bands and rubber rings remain in place after application, creating chronic ischemia and resulting in eventual sloughing of the tissues distal to the band/ring. The Burdizzo castration clamp crushes the proximal portion of the scrotum, spermatic cord, and nerves and vessels, resulting in ischemia and testicular atrophy.¹ A combination of the Burdizzo clamp and rubber ring has also been used to castrate cattle; the ring is placed following application of the clamp.^1,2

Chemical methods of castration include injection of sclerosing or toxic agents (e.g., 88% lactic acid) into the testicular parenchyma to cause irreparable damage and loss of function.^3,4 Chemical castration requires additional procedural time and technical skill, and almost twice the healing time compared with surgical castration.³ Androgen production and male behavior continued in 5 of 28 50- to 128-kg calves, indicating a high failure rate.³ In addition, healing was considered to be unsatisfactory in 25% of chemically castrated calves, compared with 3% of surgically castrated calves.³

Hormonal approaches to castration (immunocastration) usually involve injection of immunocontraceptives to induce antibody production against gonadotrophin releasing hormone (GnRH), resulting in decreased production of endogenous hormones.⁵ Although testosterone production is reduced for approximately 6 months after immunocastration, persistent mounting behavior, consumer concerns, and the need for repeat injections have made the technique less effective and desirable than traditional, physical methods.⁴

Castration of Cattle in the United States and Other Countries
Castration is one of the most common (if not the most common) procedures performed on livestock in the United States and worldwide.

In the United Kingdom, regulations require that animals older than two months be castrated by a veterinarian, using local anesthesia.⁶ Use of the Burdizzo clamp has been the most common approach in the United Kingdom, followed by surgical castration, then application of rubber rings.⁶ In contrast, use of elastrator rings is common in New Zealand, and application of the Burdizzo clamp is not.⁷ Anesthesia and analgesia are mandated for castration in Northern Europe.⁸ Castration of male calves and small ruminants is not allowed in Switzerland without anesthesia, and use of rubber rings is prohibited.⁹ In Australia, surgical castration is only permitted for animals up to 6 months old.¹⁰ Regulations in Ireland mandate use of anesthesia for surgical or Burdizzo castration of cattle older than 6 months of age.¹¹

Evidence for the Reported Benefits of Castrating Cattle
Throughout history, farm animals have been castrated to eliminate indiscriminate breeding and reduce aggressive behavior.^6,12 The procedure reduces management problems associated with aggressive and sexual behaviors, and decreases the incidence of dark-cutting meat.^4-6,12-15 Intact male cattle (bulls) tend to produce lower quality grade, less consistent, less marbled, and less tender meat.^6,14-16 In addition, carcasses from bulls command lower prices at market when compared with carcasses from steers.¹⁶

Although castration is considered to be a model of pain in animals, it is also generally accepted that the procedure results in improved overall welfare for the animal and that its economic benefits outweigh its short-term welfare costs.¹⁷

Welfare Concerns—Science, Risks, and Severity
Acute pain—All physical methods of castration cause pain.^12,18 Animals exhibit pain responses during and after castration; these responses include struggling, kicking the hind legs, tail swishing, foot stamping, head turning, restlessness, stilted gait, reduced activity, increased recumbency, abnormal standing posture, reduced interest in dams and each other, and reduced grazing and feed intake.^{3,11,14,18-22} Pain associated with the surgical and Burdizzo clamp methods is relatively immediate, whereas pain resulting from elastrator ring/band placement is slightly delayed due to interruption of the blood supply by the band/ring.^21,22 Three- to 4-week-old calves castrated using rubber rings exhibited no signs of pain at the time of ring placement; in contrast, Burdizzo-castrated calves demonstrated marked signs of pain if not anesthetized, and mild to moderate pain if anesthetized prior to castration.²²

Administration of a sedative/analgesic combination of xylazine and butorphanol did not modify painful responses to the surgical castration of 6- to 9-month-old bull calves.¹⁶ Four- to 11-week-old calves castrated surgically exhibited more pain responses and for a longer duration than those castrated using elastrator rings, suggesting that surgical castration was associated with a higher degree of pain.¹⁹

Application of a tight band around the scrotum and testes produces extraluminal compression of the arteries and veins, resulting in impeded arterial flow to and venous drainage of the tissues. Lack of perfusion compromises the supply of oxygen and metabolic substrates to the tissues and results in ischemia. Continued ischemia induces severe cellular damage and coagulation necrosis.^23,24 Ischemic lesions of the intestinal tract or limbs are widely known to cause pain during the acute phase, followed by reduced pain as the lesion progresses. Blood pressures and heart rates of 2-month-old lambs remained high 4 hours after placement of rubber rings, suggesting the persistence of pain.²⁵

Intratesticular injection of an 88% lactic acid solution in 50- to 128-kg calves resulted in similar or increased severity of behavioral responses compared with those following surgical castration.³ No significant differences were observed in scrotal swelling and pain for the first 2 days after surgery. ³ In addition, healing was prolonged and unsatisfactory for chemically castrated calves compared to those surgically castrated. ³

Effect of age on response to castration has also been investigated.^21,25 One- to 7-day-old calves castrated using elastrator rings exhibited few behaviors associated with pain or distress, and plasma cortisol concentrations of castrated calves did not significantly differ from those of uncastrated controls.²⁶ Although 6-day-old bull calves exhibited fewer violent pain responses than 21- or 42-day-old calves after castration, pain-associated behaviors were observed in all groups.²¹ Forty-two-day-old calves exhibited a high incidence of pain-associated behaviors and a marked increase in plasma cortisol concentration, possibly indicating these animals experienced more pain than 6- or 21-day-old calves. ²¹

Chronic pain—Persistent wounds were observed in 14-month-old bull calves castrated using emasculator bands; these wounds may produce chronic pain.¹⁴ Assessment of chronic pain has primarily been based on reduced weight gain and growth, but findings suggest that pain may persist for several weeks following castration.^18,22 On the basis of behavioral parameters and the presence of inflammation and sepsis, it appears that castration with rubber rings produces both acute and chronic pain, whereas application of the Burdizzo clamp and surgical castration produce less chronic pain.¹⁸ Thuer et al²² reported similar observations in 21- to 28-week-old calves. Calves castrated with rubber rings developed purulent inflammation at the site of ring placement, as well as swelling and hardening of the tissues, until the distal scrotum detached after a mean of 47 days. ²² Significantly more abnormal posturing was exhibited by rubber ring-castrated calves than by Burdizzo-castrated calves for the first week after castration. ²² In addition, calves castrated with rubber rings exhibited signs of pain in response to scrotal palpation for up to 4 weeks longer than those castrated using Burdizzo clamps. ²² Questions remain regarding the impact of chronic pain secondary to castration.¹²

Disease—Potential complications associated with castration include hemorrhage, excessive swelling or edema, infection, poor wound healing, and failure.⁴ Risk of hemorrhage is greater after surgical castration.⁴ In a survey of New Zealand cattle producers, surgical castration was associated with reportedly higher complications, including bleeding, swelling, infection, and death.⁷ Use of the Burdizzo clamp may be associated with a higher failure rate, most likely caused by operator error.^4,12

Castration-associated immunosuppression may increase risks of local or systemic disease after the procedure. Murata³² observed significant reductions in circulating white blood cells and T-lymphocyte function and significant increases in total white blood cell count and neutrophil count in 3- to 4-month-old bull calves castrated using a Burdizzo clamp; values returned to baseline by 7 days after surgery. Surgical castration causes increased haptoglobin and decreased gamma-interferon production.^13,14,20 Haptoglobin exerts a suppressive effect on lymphocyte function, and reduction of gamma-interferon results in suppression of the immune system's cell-mediated immunity and response to antigens.^13,20 Administration of ketoprofen, either alone or in combination with local administration of lidocaine, decreased haptoglobin concentrations and prevented suppression of the gamma-interferon response; therefore, administration of ketoprofen reduced immunosuppression associated with surgical castration.¹³ In contrast, administration of xylazine in combination with butorphanol had no effect on haptoglobin concentrations after surgical castration.¹⁶ Increased haptoglobin concentrations were not observed following elastrator band castration of 14-month-old bull calves.¹⁴

Necrotic tissue, such as ischemic scrotal tissues and testes after banding, is prone to infection with pathogens.³³ Similarly, the wound associated with surgical castration is at risk of infection. Clostridial organisms, ubiquitous in soil, may enter the wound and result in local or systemic infection; clostridial vaccination prior to castration is recommended.¹⁰ Use of rubber rings in calves older than 6 months may be associated with increased risks of tetanus or other infection.¹⁰

Performance—Cattle may demonstrate reduced feed intake and average daily gain (ADG) for a period of time after castration^20,28,43 Some experiments failed to detect differences related to castration method,^28,34,35,43 whereas others found that cattle castrated using bands had slower growth rates¹⁴ or lower ADG³⁶ than surgically castrated or uncastrated control animals.

Delaying castration conveys no benefit in terms of carcass weight,^14,37and taste panels suggest that consumers prefer beef from cattle that are castrated at an early age. ³⁷ Castrating beef calves immediately after transport, however, may compound the stress experienced by the calves and lead to increased losses due to illness.³⁸

Fisher et al⁵ observed that surgical castration of 5.5-month-old calves resulted in reduced ADG for the first 7 days after surgery, but calves to which local anesthetic had been administered before castration exhibited higher ADG for the same period when compared with calves undergoing surgery alone. Calves castrated using Burdizzo clamps exhibited ADG similar to control calves for the first 7 days, but ADG was reduced from the 15th to the 21st days after surgery.⁵ Surgical castration of 6- to 9-month-old bull calves reduced daily weight gain and feed intake.¹⁶ No effect of castration was observed on overall growth of 1.5- to 5.5-month-old calves for 42 days after castration using a Burdizzo clamp.³¹

Physiologic stress—Castration is considered to be one of the most stressful experiences for livestock.^14,19,27 Blood cortisol concentrations have been studied as indicators of physiologic stress in animals. Regardless of the means of castration, cortisol concentrations are increased following the procedure; however, onset, magnitude, and duration may vary with the procedure used.^1,4,18,27,28 Surgical castration appears to produce the most substantial rise in plasma cortisol concentration.^5,7,13,18,27 Application of the Burdizzo clamp may also be associated with a similar, rapid rise in cortisol concentration due to the barrage of afferent neural impulses during and after crushing of the spermatic cord and scrotal nerves.^1,18,29 Chase et al²⁸ observed that plasma cortisol concentrations increased immediately after surgical castration; animals that were banded had cortisol increases of less initial intensity, but the concentrations were similar for both procedures on the second postoperative day. Salivary cortisol concentrations observed between 15 minutes and 2 hours after castration in 4- to 11-week-old calves undergoing surgery were much higher than those of calves castrated using rubber rings.¹⁹ Stafford²⁷ observed similar overall cortisol responses for elastrator band, rubber ring, and surgical castration, but lower cortisol responses for castration using a Burdizzo clamp.

Placement of elastrator bands/rings without prior anesthesia produced a slightly lower cortisol increase than surgical castration.² Immunocastration resulted in only transient increases in cortisol concentration, likely due to stress induced by handling and injection.⁵

Age of the animal at time of castration may affect the severity of the cortisol response. Plasma cortisol levels of 1- to 7-day-old calves castrated using elastrator bands did not differ significantly from those of uncastrated controls.²⁶ Following castration by surgical, Burdizzo clamp, or rubber ring methods, post-castration cortisol concentrations returned to baseline values more quickly in 6- and 21-day-old calves than in 42-day-old calves.²¹ Use of a Burdizzo clamp or surgical castration produced a minimal response in 11-week-old calves, but a more profound response in 24-week-old calves.³⁰ Cortisol responses of 1.5-month-old and 4.5-month-old calves castrated using a Burdizzo clamp were approximately one-half and one-third, respectively, of the cortisol responses of 5.5-month-old calves castrated using the same method.³¹

Anesthesia and Analgesia
Effectiveness—Application of local anesthesia prior to castration is mandated in some countries, and significantly reduces the cortisol response to castration.^1,22,27 Administration of lidocaine into the testicular parenchyma and distal scrotum virtually abolished the cortisol response to castration when elastrator bands or rubber rings were used on 3-month-old calves.²⁷ Serum cortisol concentrations returned to baseline values within one hour of castration, and remained at those levels for the remainder of the 72-hour sampling period following lidocaine injection into the spermatic cords and scrotal neck.²² Local anesthesia had less effect on cortisol concentration when Burdizzo clamps were used, and a minimal effect with surgical castration.²⁷ In another study,²² local anesthesia with lidocaine significantly attenuated the increase in plasma cortisol concentration after Burdizzo clamp castration. Lidocaine injected into the scrotal neck almost abolished the cortisol response to a combined clamp-ring castration approach in lambs, and injection into the spermatic cord reduced cortisol responses by 45% compared with animals castrated without local anesthesia.¹ Similar results were obtained when lidocaine was administered before rubber ring placement in lambs, but no beneficial effects were observed from administration of local anesthesia prior to castration using a Burdizzo clamp.^1,27 Suppression of the cortisol increase by local anesthetics is short-lived, and cortisol concentrations increase once the pharmacologic effects of the anesthetic agent have ceased.^5,11,13 Administration of local anesthetic prior to surgical castration of 5.5-month-old calves resulted in improved ADG for the first week after surgery as compared with surgery alone, suggesting a longer duration of benefit.⁵

Epidural anesthesia or local anesthesia prior to castration using a Burdizzo clamp did not significantly reduce the integrated (area under the curve) cortisol response in 13-month-old bull calves compared with use of the Burdizzo clamp alone. ¹¹ Although peak cortisol response was reduced approximately 30% by administration of an epidural, suppression was only observed for the one-hour duration of effect for the epidural. ¹¹

Administration of ketoprofen, either alone or in conjunction with local anesthetic, significantly reduced the cortisol response associated with castration.^11,13.27 Cortisol responses of 22-week-old calves to which ketoprofen was administered prior to castration were similar to those of uncastrated controls, and the calves exhibited comparable growth rates for at least 7 days following castration. ¹³ Administration of ketoprofen also reduced the postoperative rise in plasma fibrinogen concentrations; this increase was not attenuated by administration of local anesthetic alone.¹³ The combination of local anesthesia and preoperative ketoprofen virtually eliminated the cortisol response to castration in 3-month-old calves, regardless of method used.²⁷ Ketoprofen administered to 13-month-old bull calves reduced cortisol response by 52% compared with cattle to which local anesthesia was administered prior to castration, and by 58% compared with cattle to which epidural anesthesia was administered prior to castration. ¹¹ Calves to which ketoprofen was administered prior to castration exhibited increased feeding and rumination activities and fewer pain-associated behavioral responses than those castrated without ketoprofen.¹¹

Access—Obstacles to the provision of pain relief to cattle include limited availability of some pharmaceuticals and costs associated with their use.^39,40 The only NSAID approved for use in cattle in the United States is flunixin meglumine, and its approval is for control of fever associated with respiratory disease or mastitis, and fever and inflammation associated with endotoxemia, rather than for control of pain. Use of flunixin meglumine is complicated by its intravenous route of administration (significant tissue reactions have occurred after intramuscular administration). It would be useful to determine whether flunixin meglumine is an acceptable substitute for ketoprofen, or that ketoprofen is preferable and so supported for extralabel use under the Animal Medicinal Drug Use Clarification Act of 1994 (AMDUCA). Ketoprofen has a short half-life and a withdrawal time of 7 days is recommended.⁴² Improving the availability of approved, easily administered NSAIDs in the United States is necessary for safe and uniform use. ^39,41 Use of pharmaceuticals, which may be accompanied by a need for additional veterinary assistance, adds to production costs; however, research conducted in New Zealand suggests the associated increase is small in relation to overall farm costs.⁴³

Summary
Castration is considered to be a necessary management practice for cattle. Although younger cattle exhibit less pain, stress, and distress in response to the procedure, all methods of castration induce pain and physiologic stress in animals of all ages. Pain and physiologic stress resulting from castration should be minimized to provide for the overall welfare of the animal. Although obstacles to immediate implementation exist, research results suggest that application of local anesthesia and the administration of analgesics have the potential to minimize or eliminate pain and stress associated with castration.

References

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