Ahead of each mating season, many farms will arrange for their vet to carry out a health and fertility assessment of their breeding males. This assessment involves a physical examination of the animal(s) in question as well as the collection and evaluation of a sample of semen. In some cases, a procedure known as electroejaculation (EEJ) is used to obtain this sample, but what does this involve, and should it continue to be allowed on UK farms? 

What is electroejaculation? 

Electroejaculation (EEJ) refers to a procedure whereby, following a thorough physical examination by a vet, a probe is carefully inserted into the rectum of the animal and a series of short electrical pulses are applied to the pelvic nerves and tissues, causing that animal to ejaculate.  

The probe used is species specific, i.e. appropriately sized and shaped for the animal in question, and the electrical pulse is delivered in a controlled manner by a trained operator. In the UK, the 1966 Veterinary Surgeons Act (amended by the 1988 Order) states electroejaculation may only be carried out by a veterinary surgeon. Elsewhere in the world, some countries do not require a veterinary surgeon to be present whilst others have banned EEJ entirely. 

Why is semen collected? 

Semen is collected and analysed to identify sub fertile or infertile males. This enables the stockperson to manage the remaining herd/flock accordingly, to optimise productivity and to protect animal health and welfare.  For example, additional males may need to be purchased, female group sizes adjusted, or mating periods altered to accommodate reduced “ram-power”.  

A study of 368 bulls undergoing this so-called breeding soundness examination found 33% of bulls failed to meet minimum standards, rising to a 52% failure rate in bulls over 6 years old. In another study, only 50-60% of bulls failing breeding soundness examination could be identified based on physical examination alone, the remainder would have appeared suitable but were identified as infertile/sub-fertile on semen examination. 

Without semen analysis, sub fertile males would unknowingly be used, resulting in low pregnancy rates and (depending on management system) extended mating periods. These effects may not be evident until scanning time several months later and can have long term impacts. 

  • Non-pregnant animals will likely need to be sold as commercial holdings cannot afford to carry unproductive animals 
  • Non-pregnant animals that can be retained for future breeding are likely to gain weight whilst not pregnant, resulting in reduced future fertility and increased calving/lambing difficulties which negatively impact on animal welfare 
  • Extended mating periods make feed, vaccination and body condition management during pregnancy much more difficult, resulting in increased risk of energy or calcium deficits in pregnant animals, disease, and dystocia (birthing difficulties) at lambing/calving time 
  • Extended mating periods also mean extended birthing periods and uneven batches of youngstock to rear. This increases disease risk and reduces management efficiency in terms of staffing, feeding, vaccination, parasite control, weaning and sale. 

Semen collection may also be undertaken for storage purposes or as part of an artificial insemination (AI) program. In these situations, EEJ is usually not the preferred method of collection as we will discover later, but on most farm where we are looking to identify fertility problems through single sampling, EEJ is considered more practical.  

Why use EEJ? 

EEJ is a safe, effective method of collecting semen in a regular farmyard setting.  

Farming has one of the poorest safety records across all industries and when it’s a case of getting in between a ton weight of enthusiastic but inexperienced young bull and the 600kg moving target of his affections, in the least muddy part of the farm you can find, whilst simultaneously trying to protect the safety of a couple of other stock handlers who’ve probably never been involved in semen collection before…well I for one am thinking there must be a safer way!  

Collection without EEJ can and is done, but requires experienced handlers, trained bulls/tups and suitable facilities which just aren’t available on most farms.  

Instead, EEJ is carried out with a tup carefully and calmly restrained or a bull in a suitable handling crate, the vet monitoring and controlling the electrical stimulus being delivered and someone collecting the semen sample from a safe position alongside.  

EEJ also allows multiple males to be assessed at one visit and does not require hormonal manipulation of female fertility, as no in-season female is required.  

What are the alternatives to EEJ? 

Semen can be collected using other techniques. The two most common are: 

Artificial vagina 

An AV is warmed collection vessel that the operator must redirect the bull/tup into as he jumps to mount an in-season (sexually receptive) female. This collection method is considered the “gold standard” in terms of collection for breeding purposes because it 

  • Is likely to give a better sample in many cases  
  • Can be performed repeatedly over the day or on several consecutive days to collect larger volumes of semen 
  • Gives a better indication of libido, and mating ability  
  • Can be used to follow up where initial EEJ samples have been suggestive of a problem, particularly the case in of high economic or genetic value animals where it would be a significant loss to the herd/flock/breed if they were to be removed. 

There are however challenges of AV collection including; 

  • An in-season female (known as a teaser) is required. This is achieved using hormone treatments to manipulate the cycle of one or more females.  
  • Both the teaser female and the male must be suitable for, and accustomed to, safe handling. For cattle this usually means halter training which many commercial adult animals have not experienced before. 
  • The male being collected from should be trained to jump the teaser female whilst on a halter and using an AV. This can be a time-consuming process ahead of collection day and even with this (but certainly without) it may take many attempts and significant time to obtain a sample on the day. 

Transrectal massage  

This technique, involving manual massage of the ampullae and prostate gland, may allow collection of a semen sample in some bulls, but this is not considered to be a reliable method alone.

Vaginal collection

While retrieval of semen from the vagina of a recently mated female is also possible, the analysis of the sample is limited and the semen would not be suitable for storage or insemination.  

Is EEJ painful?  

Ruminants can be very stoic and may show very little behavioral signs of pain, so how do we ensure that animal welfare is protected when using the EEJ method?  

Various studies have looked at a range of different parameters in an attempt to assess the impact of EEJ and it seems fair to say that results are variable.  

Some studies looked at cortisol (stress hormone) levels and found a small increase during and immediately after EEJ but concluded that levels returned to normal very quickly and that cortisol will rise during natural mating anyway. 

Other investigations have found no aversion to re-entering handling facilities following EEJ, which may suggest that there is no lasting distress caused. A 1996 study New Zealand concluded that EEJ in rams was no more distressing than part-shearing or simple restraint, based on assessment of animal movement through the handling facilities and on cortisol levels.  

Given that blood cortisol levels change during what would be considered non-painful procedures such as shearing, or handling with no treatment, it has been suggested that vocalisation may be a better indicator of pain in ruminants. Using this parameter, several studies have concluded that EEJ does appear to be associated with pain and therefore vocalisation but again, results are variable.  

Local or epidural (spinal) anaesthetic has been used experimentally both to look at whether EEJ is painful, and also to establish if anaesthetic could be used routinely to improve this procedure, however some studies found the benefit of local anaesthesia to be statistically insignificant. Consideration must also be given to the risks associated with epidural anaesthesia, and both human and animal safety concerns around handling a large animal that may become unsteady on his feet within a confined space.  

Should EEJ be allowed on farm?  

From personal experience of using EEJ in tups and bulls, as well as having participated in AV collection from both, I would suggest that EEJ does have a role to play as part of a whole farm management plan providing it is carried out by a veterinary surgeon trained in its use, and that we continue to look for ways to improve and refine the technique to protect animal welfare.  

Using EEJ equipment which allows the operator to adjust the intensity and duration of the pulse delivered (rather than on/off or high/low as some tup testing probes offer) allows the procedure to be tailored to the response of the individual animal. When this can be done, most tups and bulls do not seem overly perturbed by the whole experience (in fact often they appear less unsettled than any human males observing the procedure being carried out!). 

With appropriate facilities, experienced staff, trained animals and ample time, the AV collection method remains the preferred option where repeated collections will be required, but EEJ has a role to play on commercial farms without those resources and when working with animals much less used to close handling.  

EEJ is safe, practical, effective and reliable, allowing analysis of a semen sample which can play a significant part in protecting whole farm health and welfare, as well as productivity. It does need to be used with care and patience however as there is the potential to cause significant distress if not used wisely, and so I believe it should remain the responsibility of a veterinary surgeon to ensure that any EEJ attempt is stopped if the animal in question shows signs of undue pain or distress. As a profession we must also continue to critically review the use of this procedure and evaluate techniques such as local anaesthesia for EEJ, as we strive to protect animal welfare throughout the herd/flock in the future. 

Further reading: 

Sheep Vet Society – Guidelines on the examination of rams for breeding 

British Cattle Veterinary Association – Pre-breeding examination certificate 

XL Vets – Bull breeding soundness examination 

Examination of bulls for breeding soundness – an illustrated guide