Castration is performed on male cattle to prevent reproduction and make them more docile. It reduces testosterone levels. Physical castration methods include using a Burdizzo clamp or rubber rings to cut off blood flow to the testes. This causes pain and inflammation. Surgical castration removes the testes and risks infection. All methods cause acute pain responses. Rubber rings may also cause chronic pain as tissue dies. Local anesthesia can reduce pain responses but effects are short-lived. Anti-inflammatory drugs provide longer-lasting analgesia and reduce stress. Castration increases disease risk due to immunosuppression so antibiotics are recommended. Overall castration is a painful procedure and pain management should be used.

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CASTRATION
What is castration?
 To castrate a male animal means that the functioning of the testicles is stopped by preventing
production of male hormones so that the animal is unable to reproduce.
FOR BEEF CATTLE
Why are beef calves castrated?
Beef calves are castrated for the following reasons:
• To prevent them from mating after they have reached puberty by lowering testosterone levels. It is,
however, best to separate steers (oxen – castrated bulls) and heifers, because steers often mount
heifers that are on heat.
• Steers are usually more docile and easier to control than bulls. Special fences and handling
equipment are needed for bulls. WHY? – Castration reduces aggressiveness.
• Steers are finished sooner than bulls because fat deposition occurs at a faster rate than in bulls.
• Steers yield high quality carcass than bulls. Castration modifies carcass characteristics by decreasing
the number of animals with a high muscle pH (“dark cutters”). Intact male cattle (bulls) tend to
produce lower quality grade, less consistent, less marbled, and less tender meat. In addition,
carcasses from bulls command lower prices at market when compared with carcasses from steers.
When to castrate
• Castration can be done at any age up to 12 months.
• It is, however, better to do it when the animals are very young (before 2 months of age).
• Although the animals grow better when they have not been castrated, the shock of castration is
greater the older they are.
• It is also easier to handle the animals when they are very young.
Methods of castration
Several different methods of castration; however, they can be classified into three major groups:
physical, chemical, and hormonal. These groups can be divided further by technique but overall,
castration is achieved by removing the testicles surgically, damaging them irreparably, or causing them
to atrophy by stricture of the blood supply.
Physical methods
 Burdizzo
• With this method the spermatic cord and the blood vessels leading to the testicles are cut.
• The testicles tend to swell for a while and then stop functioning and
degenerate.
• Calves can be castrated when the spermatic cord can be clearly felt,
that is, from about 1 month onwards.
• They can be castrated when standing in a crush or when lying down.
• One spermatic cord should be clipped at a time. It is important to clip
the 2 cords at different levels so that the scrotal sack will receive
enough blood otherwise it will become gangrenous.
• Make sure that the spermatic cord is between the Burdizzo blades.

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Advantages
• The method is bloodless.
• Infection or maggot infestation seldom occurs.
 Rubber rings (elastrator)
• The rubber rings are put on (using an instrument called
an elastrator) between birth and about 10 days of age.
• If applied later, calves could get tetanus or a general
infection. The animals also feel more pain and this
impedes growth. Ensure that both testes are descended
into the scrotum before applying the ring.
Advantages
• Calves are handled easily and little labour is involved.
• It is a bloodless method.
 Open wound castration (emasculator or knife)
• Before the operation, the person doing the operation must wash his hands well, the instruments must
be boiled and the scrotum disinfected thoroughly with iodine or another suitable disinfectant.
• Apply antibiotic powder to prevent infection, and a fly
repellent.
• A sharp knife is used to remove the lower third of the
scrotum, and each testicle is removed from its
supporting membranes. Do not remove too little of the
scrotum otherwise it will not drain well.
• The emasculator has a cutting and a crushing surface.
The instrument is placed on the spermatic cord and the
vascular supply closed so that the testes are removed
while excessive bleeding is prevented by the action on
the vascular tissue.
• If the knife is used, the cords should not be cut
“cleanly”. The instrument is held at an angle, and
scraped over a distance of about 30 mm, until the cord breaks. This prevents too much blood flow.
• It is better to use the emasculator rather than the knife.
Advantage
• Castration is irreversible because the testicles are removed.

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 Short scrotum method
• Rubber rings are used to hold the testicles in the body cavity after they have been pushed up.
• This means that the testicles continue to produce hormones but do not produce live sperm.
• Be careful to push the testicles well up into the body cavity before putting on the rings otherwise
some live sperm may be produced.
Advantage
• When this method is used the calves will grow into sterile bulls with better growth and feed
conversion rates than steers, but may have behaviour problems (lively, aggressive).
Chemical Methods
• Chemical castration includes injection of sclerosing or toxic agents (e.g. 88% lactic acid) into the
testicular parenchyma to cause irreparable damage and loss of function.
• Chemical castration requires additional procedural time and technical skill, and almost twice the
healing time compared with surgical castration.
Hormonal Methods
• Hormonal castration (immunocastration) typically involves injection of immuncontraceptives to
induce antibody production against gonadotropin releasing hormone (GnRH), resulting in decreased
production of endogenous hormones.
• Immunocastration has been shown to increase live weight, hot carcass weight, average daily gain,
and dressing percentage following castration when compared with surgical methods.
• 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.
AFTERCARE
• Watch cattle closely for about 10 days after castration.
• Beware of blowfly attacks and infection especially with the emasculator method. Treat wounds with
wound aerosol which discourages fly attacks.
• If swelling and pain are severe and if the animal develops a temperature, a suitable antibiotic should
be injected.
PAIN
 Acute pain
• All physical methods of castration cause pain.
• 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.
• Pain associated with the surgical and Burdizzo clamp methods is relatively immediate, whereas pain
resulting from elastrator ring/band placement is delayed due to interruption of the blood supply by
the band/ring.
• Burdizzo castration also causes a more severe inflammatory response than band castration.
• Three-to four-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.
• 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.

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• 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. 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.
• Intratesticular injection of an 88% lactic acid solution in 50- to 128-kg calves resulted in similar or
increased severity of behavioural responses compared with those following surgical castration.
• No significant differences were observed in scrotal swelling and pain for the first two days after
surgery.
• In addition, healing was prolonged and unsatisfactory for chemically castrated calves compared to
those surgically castrated.
• Effect of age on response to castration has also been investigated.
• One- to seven-day old calves castrated using elastrator rings exhibited few behaviours associated
with pain or distress, and plasma cortisol concentrations of castrated calves did not significantly
differ from those of uncastrated controls. Although 6-day-old bull calves exhibited fewer violent pain
responses than 21- or 42-day-old calves after castration, pain-associated behaviours were observed in
all groups. Forty-two-day-old calves exhibited a high incidence of pain-associated behaviours and a
marked increase in plasma cortisol concentration, possibly indicating these animals experienced
more pain than 6- or 21-day-old calves. Substance P was significantly increased in calves that were
castrated. This suggests that substance P is likely associated with nociception (pain) and may become
a validated method of pain assessment in food-producing animals.
 Chronic pain
 Persistent wounds were observed in 14-month-old bull calves castrated using emasculator bands;
these wounds may produce chronic pain.
 Calves castrated with rubber rings developed purulent inflammation at the site of ring placement, as
well as swelling and hardening of the issues, until the distal scrotum detached after a mean of 47
days.
 Significantly more abnormal posturing was exhibited by rubber ring-castrated calves than by
Burdizzo-castrated calves for the first week after castration.
 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. So although banding may
cause less immediate discomfort than surgery, the overall impact of banding may be greater (e.g.
greater overall reduction in food intake and daily gain).
SURGICAL COMPLICATIONS
• Potential complications associated with castration include haemorrhage, excessive swelling or
edema, infection, poor wound healing, and failure.
• Use of the Burdizzo clamp may be associated with a higher failure rate, most likely caused by
operator error.
Haemorrhage - Risk of haemorrhage is greater after surgical castration.
• In a survey of New Zealand cattle producers, surgical castration was associated with reportedly
higher complications, including bleeding, swelling, infection, and death.37
Disease — Castration-associated immunosuppression may increase risks of local or systemic disease after
the procedure.

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• Murata 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.
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.
• Studies indicate that castration-associated leukocyte depression may be limited or eliminated by pre-
surgical administration of a local anesthetic and a systemic analgesic.
• 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.
• In contrast, administration of xylazine in combination with butorphanol had no effect on
haptoglobin concentrations after surgical castration.
• Increased haptoglobin concentrations were not observed following elastrator band castration of 14-
month-old bull calves or ring castration of 6-month old bull calves when given flunixin meglumine
in combination with local lidocaine use.
• Necrotic tissue, such as ischemic scrotal tissues and testes after banding, is prone to infection with
pathogens.
• 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.
• Use of rubber rings in calves older than 6 months may be associated with increased risks of tetanus
or other infection.
Performance—Cattle may demonstrate reduced feed intake and average daily gain (ADG) for a period of
time after castration
• Delaying castration conveys no benefit in terms of carcass weight,and taste panels suggest that
consumers prefer beef from cattle that are castrated at an early age.
• A recent study found that bulls castrated at a later age were 3% more likely to require treatment for
bovine respiratory disease (BRD) than bulls that were castrated early.
• This can cause profit loss due to an increase in the number of days to market, decrease in hot carcass
weight and potential carcass value.
Physiologic stress—Castration is considered to be one of the most stressful experiences for livestock.
• 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.
• Surgical castration appears to produce the most substantial rise in plasma cortisol concentration.
• 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.
• Placement of elastrator bands/rings without prior anesthesia produced a slightly lower cortisol
increase than surgical castration

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ANESTHESIA AND ANALGESIA
Local anesthetics— Application of local anesthesia prior to castration is mandated in some countries,
and significantly reduces the cortisol response to castration.
• 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.
• In several studies, local anesthesia with lidocaine or bupivacaine significantly attenuated the increase in
plasma cortisol concentration after Burdizzo clamp castration.
• Lidocaine administered locally with flunixin meglumine may also be an effective method of analgesia
and of cortisol tempering. 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.
• 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.
Epidurals— Epidural anesthesia or local anesthesia (with lidocaine) 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.
• 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.
• Xylazine epidurals combined with intravenous flunixin meglumine produced no significant differences in
animal health or feedlot performance compared to animals that did not receive anesthesia/analgesia.
Sedation—Intravenous xylazine, alone or with ketamine, has been shown to reduce behavioral
indications of distress and serum cortisol concentrations immediately after castration.
• The addition of ketamine to more traditional chemical restraint formulas (“ketamine stun”) can increase
patient cooperation, and has been shown to lower stress response to both dehorning and castration in
calves.
Analgesia— Administration of NSAIDs results in prolonged postoperative analgesia.62 Administration
of ketoprofen, either alone or in conjunction with local anaesthetic, significantly reduced the cortisol
response associated with castration.6,21,54 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. Calves to which
ketoprofen was administered prior to castration exhibited increased feeding and rumination activities and
fewer pain-associated behavioural responses than those castrated without ketoprofen.
• Other studies have shown meloxicam to reduce but not eliminate pain-related behaviours following
castration. Meloxicam also reduced the number of animals requiring treatment for bovine respiratory
disease following castration.
Access—Obstacles to the provision of pain relief to cattle include limited availability of some
pharmaceuticals and costs associated with their use.
• 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.

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FOR DOGS AND CATS
Description of Technique
 Castration, or orchiectomy, is surgical removal of the testicles.
 For dogs with both testicles in the scrotum, a single incision is made in the skin just in front of the
scrotum.
 If one or both testicles are located in the abdomen (retained testicle or cryptorchidism), abdominal
exploratory surgery is necessary.
 If the testicle is located near the sheath (prepuce) or in the groin (inguinal testicle), a skin incision is
made directly over the testicle.
 Most castration incisions are closed with buried sutures to decrease the tendency for licking. These
sutures do not have to be removed.
 Scrotal ablation or removal of the entire scrotum (at the same time as the testes) is necessary in cases of
cancer, trauma, or infection or if the scrotum is extremely pendulous (large and baggy).
Spaying & Neutering
What do “spay” and “neuter” really mean
 Female dogs and cats are spayed by removing their reproductive organs, and male dogs and cats are
neutered by removing their testicles.
 In both cases the operation is performed while the pet is under anaesthesia.
 Depending upon the procedure, your pet may need stitches removed after a few days.
Spaying or Neutering Is Good for the animal.
 Spaying or neutering helps dogs and cats live longer, healthier lives.
 Spaying or neutering can eliminate or reduce the incidence of a number of health problems that can be
very difficult or expensive to treat.
 Spaying eliminates the possibility of uterine or ovarian cancer and greatly reduces the incidence of
breast cancer, particularly when your pet is spayed before her first oestrous cycle.
 Neutering eliminates testicular cancer and decreases the incidence of prostate disease.
 Behavioural management – entire male dogs can develop undesirable behaviours associated with their
testosterone, including:
‾ urine marking
‾ straying after bitches
‾ Aggression.
When should a dog be castrated?
 Castration can be performed from six months of age onwards; however in some cases it may be sensible
to consider delaying surgery until your dog is older.
 Timing of castration will depend on individual circumstances.
 Early castration is generally recommended if unwanted behaviours such as excessive mounting
behaviour or urine marking occur.
 Early castration may also be appropriate if an entire bitch also lives in the house hold or if it is a
stipulation following adoption.
 Dogs should always be castrated if their testicles have not fully descended by 6 months of age, as
undescended testicles are more prone to cancer.

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Postoperative Follow-up Care
 The dog should be kept quiet for 10-14 days or until the sutures are removed, especially if an
abdominal surgery was done.
 Restrict play and exercise to leash walking. If possible, except for going outside for elimination
purposes, the dog should be kept inside in a clean and dry environment until the incisions have
healed.
 No recheck visits may be needed if external sutures were not used.
FOR HORSES
When to castrate
 Castrations are normally carried out in spring and autumn. This is to avoid the flies of summer and
the mud of winter.
 It should be borne in mind that they will benefit and recover faster if
they are allowed exercise in the days following the operation and this
should be considered when planning the date.
 Both testicles must have descended into the scrotum and there should be
no other material (e.g. herniated intestine) in the scrotum before
castration is carried out.
 If there is suspicion that other material may be present within the
scrotum then the horse should only be castrated in a hospital
environment.
Where to castrate
 The operation may be carried out either at the owner's own property or at the hospital. The advantage
of carrying it out at your own property is the lesser inconvenience caused to you and your colt by
travelling. Providing you have adequate facilities then this may be your preferred location.
 If castrated at home using sedation and local anaesthetic a competent, experienced handler is
essential - preferably one who does not mind the sight of blood! Clean, warm water and a clean
environment will also be required.
 If carried out at the hospital the colt will be admitted the day before in order to allow him to be
fasted, and to settle in and get used to his surroundings. We find colts that are relaxed are better
subjects for anaesthesia the next morning. He will then be castrated in the operating theatre, which
offers the highest standards of sterility and anaesthetic equipment.
The Procedure
 Castration involves the removal of both testicles through surgical incisions into the scrotum.
 The connections of blood vessels, tubes etc. from the testicle to the body internally must also be
crushed and cut.
 There are two castration methods. The "open" technique incises open the scrotum and, having
removed the testicles, the wound is left open for postoperative drainage. The “closed” technique
involves suturing the various layers, once the testicles are removed, to prevent herniation of
intestines through the castration site.
 This latter technique takes longer and is not usually possible to do under field anaesthesia so requires
the horse to be operated on at the hospital premises.
 Standing castration using sedation and local anaesthetic can only be done using the ‘open'
technique and is suitable for horses which are well handled and have fully descended testicles.
The Risks

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Infection acquired at the time of surgery, or from mud and dust contamination subsequently, is the most
common post-operative complication. This emphasises the importance of hygiene wherever the horse is
castrated.
Bleeding is a frequent complication of the open technique but is usually, but not always, self-limiting.
As a general guide, if you can count the drips then this is of little concern compared to a constant stream
of blood. If you notice excessive bleeding we would always encourage you to contact us.
Post-operative swelling is normal and usually reaches its maximum at about five days after the
operation before reducing. Gentle exercise during this period reduces swelling.
Herniation of the abdominal contents through the wound, which is more common in foals and in those
operated on using the open technique. This risk is minimised by using the closed technique.
 If the 'closed technique' is your preference, the administration of any general anaesthetic does carry an
element of risk and, although we will do all we can to minimise this, it must always be borne in mind. As
well as preparing the horse by starving etc. the subject will undergo a pre-anaesthetic check. In very rare
cases where there is an adverse reaction, the emergency resuscitation equipment that is available at the
hospital will offer your horse the best chance of recovery. Unfortunately, this equipment is not mobile
enough to be carried to the owners' premises.
IN PIGS
WHY IS IT DONE?
 As an easier control of behaviour and enhance body weight gain.
 The higher propensity of castrates to deposit fat, a commodity that has been in high demand until quite
recently.
 It is undertaken to reduce boar taint of the pork.
Boar taint is urine or perspiration – like odour found in pork of uncastrated pigs. Compounds
responsible for boar taint include skatole, a product of tryptophan breakdown in the gut and testicular 16
– androstene steroids mainly androstenone.
Although intact boars are more efficient in feed conversion and produce a leaner carcass than surgical
castrates, the existence of boar taint in fat has substantially reduced the acceptance of the boar meat.
 Increased interest in meat production from uncastrated males is related to the declining demand for
animal fat.
 In addition, the discovery that 5–androst–16–ene –3–one is responsible for sex odour in cooked boar
meat, has stimulated interest in masking or altering the objectionable meat quality characteristics of
boars.
Removal of gonads in female (sows) i.e ovaries is also undertaken by some pig owners. However, it is
not required unless it is just for breeding management.
Age
 In Europe, piglets are castrated at average age of 10 days and at maximum of 21 days.
 For practical purposes, male pigs should be castrated surgically at the age of 30 to 45 days and
maximum of 60 days.
 As age increases more adhesions will be astablished in the scrotal pouch and testis, leading to more
bleeding and risk of shock
Steps of castration

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2. Preparation of site
 Wipe the perennial area and scrotum with
antiseptic for sterilisation (fig 2).
 Clip out the long hairs, press the scrotum
and fix the testicles. Apply antiseptic
solutions or spirit or tincture of iodine.

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The Solution
 The following alternatives to castration can significantly improve pig welfare:
Management and feeding to reduce boar taint and aggression in entire males
 Management factors that reduce boar
taint include providing clean and dry
bedded pens with separate lying and
dunging areas, diet (eg. feeding
potato starch or high fibre diets,
provided nutritional needs are met)
and providing showers.
 Pens should be designed to minimise
aggression with adequate space,
substrate material (eg. straw) and
avoiding mixing unfamiliar
individuals throughout life.

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Detecting boar taint at slaughter
 Provided the carcase can be removed from the line, boar-taint can be detected at slaughter and the
carcasses can be used in heat-processed and cold-served meats, as processing destroys the pheromone
responsible for the taint.
 Methods to detect boar taint include sensory and chemical or biochemical sorting, which could eliminate
the need for castration if their accuracy is improved in the future.
 Approximately 3% of carcases are affected by boar taint.
Genetic selection against boar taint
 Selection against the two main naturally
occurring chemicals responsible for boar taint
could mean that castration is unnecessary.
 This would take longer to implement (5-10
years of selection) and mitigating aggression
in entire males would still be required.
Female-only herds
 Rearing female-only herds is one method to avoid boar taint, which requires reliable sexed-semen for
breeding that is currently unavailable in large volumes.
 Technological developments are still needed and there is a risk of more discomfort to the female than
standard artificial insemination.
Vaccination to delay puberty
 An injection to suppress the male ‘Gonadotrophic releasing hormone’ (GnRH) leads to the delay of
puberty, and has the potential to rear heavier weight males without the risk of boar taint.
 Improvac is the brand name of the only current provider of this injection.
 Improvac improves weight gain, feed
conversion and carcass leanness after
one injection, and reduces aggression,
sexual behaviour and the risk of boar
taint after the second injection.
 Improvac is beneficial for welfare
because it avoids the pain and stress of
castration and reduces mounting
behaviour by males.
 It has been shown there are no
negative effects on meat quality or
consumer

14. 14VETHACKING101
REFERENCES
1. Kent JE, Thrusfield MV, Robertson IS, et al. Castration of calves: a study of methods used by
farmers in the United Kingdom. Vet Rec 1996;138:384-387.
2. Stafford KJ. Alleviating the pain caused by the castration of cattle. Vet J 2007;173:333-342.
3. Fisher AD, Crowe MA, Alonso de la Varga ME, et al. Effect of castration method and the provision
of local anesthesia on plasma cortisol, scrotal circumference, growth, and feed intake of bull calves.
J Anim Sci 1996;74:2336-2343.
4. Stafford KJ, Mellor DJ. The welfare significance of the castration of cattle: a review. NZ Vet J
2005;53:271-278.
5. Currah, JM, Hendrick SH, and Stookey JM. The behavioral assessment and alleviation of pain
associated with castration in beef calves treated with flunixin meglumine and caudal lidocaine
epidural anesthesia with epinephrine. Can Vet Journ 2009: 50:375-382.
6. Earley B, Crowe MA. Effects of ketoprofen alone or in combination with local anesthesia during the
castration of bull calves on plasma cortisol, immunological, and inflammatory responses. J Anim Sci
2002;80:1044-1052.
7. Fisher AD, Knight TW, Cosgrove GP, et al. Effects of surgical or banding castration on stress
responses and behaviour of bulls. Aust Vet J 2001;79:279-284.
8. http://www.compassioninfoodbusiness.com/media/5823241/piglet-castration.pdf