A thorough bull examination including fertility checks can be carried out pre-season, before bull sales or to investigate a failure. Andrew Smith, from Donview Veterinary Centre, part of the VetPartners group, takes us through why you should thoroughly check bull performance, and how each step is carried out.

Why check bulls?

“A full examination before putting a bull in with the cows provides confidence he will perform and gives you a chance to act if any issues are detected,” said Mr Smith. “The bull check service is also a helpful tool when selling a bull, as it offers assurance and confidence for buyers.

“It can also prevent any comeback if there are issues down the line, as it provides proof that that the bull was fit and well at the point of sale.”

Bull examinations may also be carried out to investigate a failure, such as poor PD scanning results. “In this kind of situation, it’s important all factors are investigated with bull performance included,” he added.

Since the Donview practice first offered the service in 2012, there has been a steady increase in the number of farmers using it. “We now have about 50% of pedigree herds using it, usually prior to selling what can be an £8000-£10,000 bull at the sales.”

Mr Smith highlighted that although the value is obvious when testing pre-sales, many commercial herds could benefit by carrying out bull checks pre-season to identify and replace sub-fertile bulls who could be impacting calving intervals amongst other things on-farm.

Physical examination

He explained their bull check process is based on the BCVA standard, which starts with a physical examination – this is a general assessment of the health of the bull, including confirming he is structurally fit.

“We check their back, legs, heart, lungs and the state of their teeth. These are all important, as there’s no point in having a fertile bull if he’s got a problem with his back or heart to prevent him from physically doing his job.

“We then look at the reproductive organs specifically. This includes measuring the testicles to find out the circumference, looking for any lumps, bumps, abscesses or scarring. We also make sure they’re roughly the same size and texture, as it’s something they can fail on, particularly for the breed society sale inspections.”

Mr Smith said different breed societies have different inspection standards, so they base any pedigree pre-sale check on the appropriate breed standard.

Semen analysis

“If we’re satisfied following the physical examination, we’d then get a semen sample for analysis. We use an electro-ejaculator to stimulate the bull using a very low current, capturing the resulting sample in a pot on the end of a pole," said Mr Smith.

“Once a sample is collected it needs to be evaluated while it’s fresh and at body temperature to ensure accurate results. We then score the gross motility of sperm using a heated stage on a video microscope set to a low magnification using a one to five scale, with a score of four or five indicating very good or excellent gross motility.”

The next step is to increase magnification to measure the progressive linear motility, which checks the sperm are swimming in a straight line, rather than just flapping about or moving in circles. This is crucial to their ability to reach the egg.

“If samples are poor, we can retest the bull after a five-minute break, as it could simply be a problem with that particular sample.”

High mag examination

Following the semen analysis carried out on-farm, stained smears are prepared and taken back to the practice for more extensive analysis.

“At the practice we look at the samples using a high magnification, looking for any abnormalities, like coiled or bent tails, retained cytoplasmic droplets or detached heads. If there’s a lot of sperm with one type of abnormality this can indicate what the problem is.

"For example, lots of retained cytoplasmic membranes are a sign of immaturity, so the issue would likely clear up once the animal is older," he said. “For a pass, we’re looking for 70% of sperm to be clinically normal.

“However, it is not a simple pass or fail. Bull checks can often identify sub-fertile bulls who are only doing their job properly about 60% or less of the time.

"Long-term, these animals can be as costly, as they can lead to prolonged calving periods, so these are the bulls commercial herds may want to pick out to improve long term profitability. It is estimated one in five bulls are sub-fertile.”

The decision on whether to retest a bull with poor results depends on the situation. “If it’s an old bull, or a bull with a physical issue and it fails, you may not bother retesting, but for a young bull where you weren’t expecting any issues you would probably retest 1-2 months later,” he concluded.

Case study: Andrew Sleigh, Newseat of Tolquhon, Tarves, Ellon.

Andrew breeds Salers and Simmentals as part of a mixed farming enterprise, with a 150-cow suckler herd, including 20 Simmentals, with the rest Salers and Salers crosses.

Each year he aims to sell at least eight young Salers bulls and one or two Simmental bulls. “I’ve been using the bull check service at Donview vets for about five years, mostly for checking young bulls before the sales. The checks provide peace of mind that the bulls are healthy and will perform,” he said.

Mr Sleigh added that with a good bull, the checks only take about 10 minutes, although it can be longer if the bull doesn’t settle or there’s difficulty getting a sample.

“The vets do the checks and look at the samples under the microscope and tell us the results straight away. It’s not 100% assurance, but it allows me to be confident that I’m selling healthy bulls that will be able to do their job.”