Buying a stock bull this year? Here’s a few words of advice

“Buying a stock bull is easy – making sure he gets cows in calf in a compact breeding season for several years is more difficult,” Dr. Norman Weatherup, a senior beef technologist at the College of Agriculture, Food and Rural Enterprise (CAFRE) explains.

He gives his top tips on getting the most bang for you buck when it comes to buying a bull this year.


Bulls are often purchased with “little or no thought given to health status”, Weatherup warned.

“Many breed societies now have a mandatory requirement that herds must be participating in an accredited health scheme, before animals can be sold at official sales,” he said.

“While this is a positive step forward, and is to be commended, purchasers should pay special attention to the health status of the animal and think through the implications for their own herd.

Ideally, the purchaser should have his herd vaccinated before he brings in any animals at all and the new bull should also be vaccinated before he joins the herd.

“Make sure all booster injections are administered according to manufacturer’s instructions and that vaccines are handled carefully.”


In the case of Johne’s disease, Weatherup advises it is “pointless” testing a young bull under two years old.

“Even if a bull does have Johne’s, he may test clear at this age – only for the disease to become apparent at a later stage,” he said. “The best approach is to purchase from a Johne’s Risk Level 1 herd.

“Any foot trimming required should also be completed at least six to eight weeks before the start of the breeding season, as feet and legs do a lot of work in this period.”

Scrotal circumference

Scrotal circumference is easily measured and is closely related to both volume of semen and percentage normal sperm cells.

Research has also found a strong genetic relationship between scrotal circumference in bulls and the fertility of their daughters as measured by age at puberty, Weatherup explains.

“The minimum industry requirement established for 12-14 month old bulls across all breeds is a scrotal circumference of 30cm. Avoid bulls which do not meet the minimum standard,” he said.

When to buy a stock bull?

Weatherup also advises buying a stock bull at least three months before he is needed.

He said: “A bull is often bought a very short time before he is turned out with cows. Because many farmers only select breeding stock by eye, young bulls are often fed intensively to achieve the highest weight gain and fat cover possible.

“While these young bulls will look exceptionally well on sale day, the fat deposited around the neck of the scrotum will adversely affect sperm production for the rest of their lives, their feet may be permanently damaged and they may not be able to mate as many cows as they should.

Often, these bulls are turned out to too many cows with too little feed – so they lose a lot of weight in a very short time, which also adversely affects fertility.

“Clearly, it is better to buy a bull before he gains excessive condition – or else at least three months before he is needed to start serving cows, to allow time to return to moderate body condition.”

To summarize

Dr. Weatherup’s top tips in brief:

  • Have a bull in fit – not fat – condition before turning him out with cows;
  • Buy a bull at least three months before he is to be used and ideally as early as possible;
  • Ensure that a purchased bull comes from a herd with at least the same, if not higher, health status than your own, and that all vaccinations and health treatments are completed well before breeding season.