An interview with Kenny Johnston BVM&S MRCVS; Cert CHP; MIScT

What’s your background?

I am from Edinburgh and spent a lot of my childhood on farm in Borders. Like most large animal vets, I would love to have farmed. After school I worked for number of years as a lab technician then went to Edinburgh University to train as a vet. On graduating I worked in Campbelltown for three years then worked in the West Midlands for a year before coming to Tain in Easter Ross where I have now lived for 35 years.

In practice my key interest was always cattle. I gained the Certificate in Cattle Health and Production in 1990.

Outside of work I played basketball for Scottish Universities and captained the University football team continued playing amateur football until my mid-50s. As a way if winding down I have almost completed climbing all the Munros.

You run a bull fertility business. How did you get involved with that?

Many years ago, when I was in practice some of my clients were having problems with fertility in their cow herd. Tests for diseases, mineral deficiencies and nutritional issues didn’t give an answer. When I was doing health plans, I found that a number of people had low calving percentage in first three weeks of calving. It was then apparent the two problems were both down to the bulls. So, we needed a way to test bull’s fertility. As no-one was offering a local testing service I went on a course and started offering the service.

I grew the service while I was still in practice and when I retired, I set up a new business to carry on doing it because few practices locally were offering the service. I now cover from Sutherland to Kintyre and some of the islands testing between 120 and 150 bulls each year

What is bull fertility? What are the issues, causes, consequences?

Rather than bull fertility I prefer to call it bull breeding soundness as this covers physical issues such as locomotion, lameness, condition scoring, checking general health and eyesight. The yardstick for a fertile adult bull is being able to serve 40 disease free cycling cows and get 90% in calf in nine weeks with 65% in calf in the first 3 weeks.

Did you know that up to 25% of bulls cannot do that? I still find that many farmers are unaware of this and commonly report that bulling had initially been a bit slow but picked up later on. This is the classic picture of a sub-fertile bull.

Kilos are king at sale time. So, any delay in a cow calving costs money, even more so at recent calf sale values approaching £3/kg. A sub-fertile bull can lose a farm business up to £2500 over three weeks. Add a cull value of £1500 and you have a £4000 bull.

Any stories about infertile bulls?

Where do I start there are so many? One which really took me aback and I will admit to letting my professional front slip on this one. A farmer had bought a very well-bred young bull privately. He was very proud when showing me the bull and describing the incredible pedigree he had and the prizes his ancestors had won. He certainly looked the part until I bent over to look at his testicles. I couldn’t help myself and said 'bloody hell I’ve castrated bigger calves than this.' A lesson for all concerned there.

I was asked to investigate a herd with two bulls serving 40 cows and three weeks into the calving period still had no calves. I tested the bulls and both were almost completely infertile. He immediately bought two replacement bulls got the two new bulls got them tested and they were OK. The bit I cannot understand is why he didn’t get the new bulls tested the next year to ensure he didn’t have a repeat financial disaster. Why did they not invest in an inexpensive test which gives reassurance that you actually have bulls capable of their job before you put them out?

One interesting case I had was a call from a pedigree breeder who had bought a very highly valued bull with rare genetic bloodlines. He had run with 20 cows and scanning showed none were in calf. The examination of the semen revealed 96% of the sperm were carrying a rare heritable genetic defect which caused the production of abnormal sperm.

How often should bulls be tested and when?

I find a lot of farmers think that even if tested other things could wrong (lame) so what is the point. The real value is finding the sub-fertile and infertile bulls and not using them. What is the point of putting a bull that isn’t working out with your cows?

I commonly get calls from folk who report a poor scanning result asking if can test their bull. It’s pointless by then, it’s too late.

Testing should be done every year, ideally six to eight weeks before bulling. This gives an accurate picture of the bull’s capability and time to find a replacement.

What does the test cover? What do you look for in a good sample?

There is a standard examination designed by the British Cattle Veterinary Association. This firstly involves measuring the scrotal circumference which is compared against the size expected for the age of the bull by each breed society. Then an internal examination is done to assess the state of the internal accessory sex glands. The physical state of the penis is assessed during semen collection.

With regard to semen, it is examined immediately on collection under a microscope to assess the percentage of sperm actively moving. This needs to be over 60%. A microscope slide of semen is prepared by adding a stain and examining the sperm under the microscope. 100 sperm are counted and assessed to calculate the percentage of normal sperm. This must be over 70%

Other parts of the test include checking eyes, heart, lungs and where possible, locomotion.

If all is satisfactory then a British Cattle Veterinary Association certificate stating the bull is suitable for breeding is issued. Any issues found are noted on the certificate.

Are there any problems with bulls after fertility testing?

There is no evidence of problems following bull fertility testing. The system is used world wide and there are no problems reported.

Does having bulls in 'show condition' affect fertility?

Yes. I am aware of a review of insurance claims done a few years ago. It found that 30% of bulls sold at the major bull sales the previous year were subject to claims for fertility.

Young bulls which are overfit carry excess fat in the scrotum leading to poor heat regulation causing a reduction in sperm production. Other issues are pressure on joints and bones causing leg issues later in life. There are diets which can get bulls to a level of condition which sales seem to demand but minimize the level of fat in the scrotum.

Going from a high concentrate, low forage diet to a mainly forage diet causes nutritional stress. Equally putting bulls from a forage diet to a high concentrate diet can cause nutritional stress. A few years ago, I tested 15 young bulls going to sale who had been started late on feeding and 10 failed their fertility test.

I firmly believe all young bulls going for sale at marts or privately should be fertility tested before sale, if for nothing else to reassure the buyer and safeguard the seller.

Are there any things to watch for after a bull with a good result goes out with cows?

One of the things not usually assessed during the examination is the ability to serve a cow. So, it is important bulls are watched during mating and records kept of cows bulling so problems can be identified at an early stage.

Are there any disease risks with fertility testing?

As long as the equipment and workwear used are properly cleaned and disinfected there should be no problem.