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Clamp castration (Burdizzo)
Explore the advantages and disadvantages of clamp castration (Burdizzo), including the impact on productivity and profitability.
Advantages of clamp castration:
- Can be used on lambs up to three months of age (on farm), and on older lambs by a vet
- Ewes and rams can be managed together
- The clamp is a one-off purchase
Disadvantages of clamp castration:
- Can be difficult to carry out correctly and effectively
- Requires training
- More time-consuming than rubber ring castration
- No visual indication of effectiveness – risk of incomplete castration
- Short-term moderate to severe pain for the lamb
- Possible increased feed intake of castrated lambs
Table 1. The impact of clamp castration compared with leaving rams entire
| Measure | Impact |
|---|---|
| Welfare (relative to entire lambs) | Mixed* |
| Productivity | Negative |
| Profitability (added value) | Positive |
| Environmental sustainability: GHG, air and climate, biodiversity | Negative |
*Increased welfare compared with rubber ring castration (elastration)
Table 2. Considerations for clamp castration
| Implementation | Rating |
|---|---|
| Cost | £ |
| Speed | Fast |
| Production system | All systems |
£ No new equipment or time constraints over and above existing business-as-usual running costs
What is clamp castration?
This method involves applying a clamp (also known as a bloodless castrator or Burdizzo device) to the neck of the scrotum. This crushes the spermatic cords, stops the blood supply and destroys the nerves, causing the testicles to waste away.
To maintain the blood supply to the scrotum so that it does not waste away, you need to apply the clamp correctly and for the right length of time, i.e. long enough to destroy the relevant tissues but not too long that it affects the scrotum.
The clamp must be applied twice, with each application taking at least 10 seconds.
It is important that you are adequately trained to carry out clamp castration.
Where can this practice work?
Clamp castration is suitable for hill, upland and lowland systems.
As the Mutilations (Permitted Procedures) (England) Regulations 2007 permits the use of clamp castration without anaesthetic up to three months of age, it is a viable method for extensive systems (where lambs are usually older than seven days when they are gathered for castration).
A vet must carry out the procedure if lambs are older than three months.
How much does clamp castration cost?
You can buy castration clamps from many agricultural suppliers, prices ranging from £50–150. It is important that you select the correct size for lambs (9–12 inches) – larger devices designed for cattle will not be suitable.
The cost of operator training, which is essential for animal welfare and the success of the procedure, could reduce uptake of this practice.
You also need to consider the cost of a failed clamp castration. In this situation, you may need to pay for surgical castration at an older age and/or see unwanted pregnancies.
Clamp castration is more time-consuming and, therefore, costly in terms of labour than rubber ring castration. However, as the time spent gathering and handling lambs would be similar, this will only have a significant impact on larger flocks.
How can clamp castration be done well?
This technique requires each spermatic cord to be clamped twice, with the second application applied below the first. It is important that you can feel the spermatic cord between the jaws of the clamp for the duration of each application.
Stagger the clamp site on each spermatic cord to prevent complications from a complete loss of blood supply to the scrotum. Hold the clamp in place for 10 seconds on each cord to ensure that the relevant tissues are destroyed.
Clamp castration can be difficult to carry out effectively, especially on very small lambs.
There is no obvious visual sign of effective or ineffective castration as the testes waste away within the scrotum, which does not fall off.
Incorrect application of the clamp can result in incomplete castration, which is why training is essential. Carrying out the procedure correctly also minimises pain and discomfort of the lambs.
Maintain the clamp in good condition – check it at the beginning of lambing and throughout the season . Ensure the jaws of the clamp are parallel so that they close uniformly across their width.
What is the impact on lamb welfare?
Clamp castration causes short-term moderate or severe pain. The pain from clamp castration does not last as long as that from rubber ring castration.
Power-assisted clamps can make this task easier, however, studies show they may cause more pain, likely due to applying a greater force than is necessary.
When a clamp is used without anaesthesia or analgesia (pain relief), lambs are more sensitive to pain. While anaesthetic does not completely eliminate pain, using it before the procedure will reduce acute pain.
You can also reduce the amount of pain felt by lambs by making sure you use the correct technique – evidence has shown that lambs castrated by inexperienced students experience more pain than those castrated by experienced vets.
What is the impact on productivity?
The success rate of this method varies. Some studies indicate a success rate of only 12%, while others have shown more consistent positive results.
If you don’t carry out clamp castration correctly, it could result in unwanted pregnancies. It also means you may need to castrate animals a second time (at an older age), which will have time and cost implications.
The possibility of incomplete castration and its consequences may make clamp castration less appealing than other methods.
What is the impact on profitability?
A higher feed intake, coupled with poorer feed efficiency, could have a negative impact on profitability.
However, you can keep castrated rams alongside ewes, which decreases management and labour costs compared with managing them separately. Bear in mind the risk of failed castration though, which could result in unwanted pregnancies.
What is the impact on environmental sustainability?
There is a lack of evidence related to clamp castration and environmental sustainability. However, the reduced performance of castrated lambs and increased feed requirements could have a negative impact.
A benefit of this method is that, aside from the initial purchase of the clamp, you don’t need any consumables, e.g. rubber rings.
What are the legal implications of clamp castration?
There are relatively few legal restrictions for clamp castration.
Anyone over the age of 18 and who is “reasonably competent and humane” can carry out the procedure (without anaesthetic) on lambs less than three months old (according to the Animal Welfare Act 2006, the The Mutilations (Permitted Procedures) (England) Regulations 2007 and the Veterinary Surgeons Act 1966). An anaesthetic must be used on older lambs and the procedure must also be done by a vet.
How do farm assurance standards manage clamp castration?
Clamp castration is one of only three permitted castration techniques in the RSPCA Assured standards. Under this scheme, you can only use clamp castration on lambs aged between 24 hours and eight weeks, and only in the case of a failed rubber ring. You must seek permission to castrate animals from their Farm Animals department annually.
Both RSPCA and Soil Association standards require the use of pain relief with all castration methods.
Red Tractor and RSPCA standards require you to record planned castrations in your health plan, reviewed by your vet.
How strong is the evidence for clamp castration?
As part of our research, we found a range of studies which explore the use and effects of clamp castration on animal welfare compared with other castration techniques.
Cortisol (a stress hormone) levels and behaviour assessments were among the measurements used to determine welfare, with some studies also comparing pain levels with and without local anaesthetics/analgesics (pain relief). There were discrepancies between papers.
Lambs castrated using a clamp experience acute pain for a short period of time – when the clamp is applied. Lambs tend to recover from this procedure more quickly than from rubber ring or surgical castration.
Local anaesthetics – lidocaine and bupivacaine (neither of which are licensed in England) – do not prevent lambs from feeling pain altogether, however they do reduce the pain level. There is a lack of evidence evaluating the use of the anaesthetic procaine.
Leaving ram lambs entire, therefore, remains the preferred option where feasible.
How the three Rs can be applied
We have reviewed leaving ram lambs entire and various castration methods in terms of how they can be reduced, refined or replaced (the three Rs) and the impacts of doing so.
Strategies for reduction: There is scope to reduce the number of lambs castrated using the clamp method by ensuring you have the right management tools and infrastructure to allow ram lambs to be kept entire.
Strategies for refinement: You could refine clamp castration on your farm by making sure everyone who performs the task has refresher training sessions on a regular basis. If you don’t already do so, you should also inspect and maintain the clamp regularly. To refine the practice further, you could administer pre-castration local anaesthetic and pain relief, as well as post-castration pain relief.
Strategies for replacement: You could replace clamp castration with leaving male lambs entire.
The information on this page is taken from an AHDB-commissioned report.