Case Study: Reducing bull breakdown at Chilwell

Sarah Brown (ASHEEP & BEEF) interviews Simon Fowler (Chilwell Farms)

Simon Fowler (Chilwell Farms) is the lead producer of ASHEEP & BEEF’s ‘Preventing Bull Preputial Breakdown by Vaccination’ − a Producer Demonstration Site (PDS) project funded by Meat & Livestock Australia (MLA) and facilitated by Dr Enoch Bergman (Swans Veterinary Services).

As the PDS closes out its final year, ASHEEP & BEEF caught up with Simon to learn about the project’s impact at Chilwell. Our thanks to Simon for his time giving the following interview.

Simon Fowler with veterinarians Dr Reuben Welke and Dr Enoch Bergman.

Project background

The PDS has run over three years (2023 – 2025) and aimed to:

• demonstrate that a commercial Bovine Herpesvirus vaccine (either Rhinogard or Bovilis MH + IBR) prior to mating can reduce the incidence and severity of Bovine Balanoposthitis and hence bull wastage in virgin British bred bulls

• establish a baseline incidence of the syndrome and produce statistics useful to estimate both the cost of the syndrome to Esperance producers and the return on investment of vaccination.

Enoch has recently collated the final season of data and has been interviewing producers in the Esperance region about the 2025 breeding season. Results are again showing a reduction in the incidence of preputial breakdown in bulls vaccinated on individual farms. Final results, including cost benefit analysis, will be published in early 2026.

What is Bovine Balanoposthitis?

Infectious Balanoposthitis (IBP) is a condition caused by a herpesvirus in cattle. It leads to ulcerative inflammation of the penis and prepuce of bulls and of the vulva of cows. Like all herpesviruses, infection is permanent, often becoming dormant and may later reactivate when animals are under stress. Virgin bulls can become infected during the joining process when working with other older bulls or merely by being in contact with infected cows. (Find out more about the condition via the producer guide).

Cattle yarded at Chilwell.

Chilwell Farms overview

Chilwell Farms is owned and managed by Simon and Robyn Fowler, and Andrew and Marie Fowler.

“Andrew runs the cropping enterprises, and I run the livestock operation with seven fulltime stock team members,” said Simon. “Livestock form an important part of our mixed farming operation and we focus on the synergies between livestock and cropping to improve the whole farm profitability.”

“We use Angus bulls purchased mainly from Ken MacLeay’s Blackrock Angus Stud in Vasse and also purchase a few local bulls from Andrew Kuss’s Allegria Park Stud. They are both very good people to deal with and their stock’s genetics are well suited to the grass finishing program that we have for our steers.”

“Generally, we purchase about 25 bulls each year and the new bulls are initially used to back up our fixed time AI [artificial insemination] program on 500 heifers. They are then used in the cow herd to replace any injured bulls or improve the joining ratios.”

Dr Enoch Bergman vaccinating a bull.

Bull breakdown experiences prior to vaccinating

“Before we started our bull vaccination program, virgin bull breakdown was a large issue. We were seeing up to 50% of our first-year bulls suffering penile breakdown within the first three weeks of joining. This was having a large financial impact to both the cost of the bull and the cost of lower pregnancy rates in the cows. It was also a large disincentive to spend money on superior bull genetics as the risk of breakdown was too high.

“The other factor influencing our bull herd was losing large amounts of bulls to corkscrewing penises when we jump tested them. This has dramatically reduced since we started vaccinating from as many as 15 bulls out of 80, to about 4 bulls.

Two bulls that were identified with preputial damage in the 2025 season.

“Previously, we thought that preputial breakdown was caused by physical damage from fighting and accidents. We are now very confident that a large amount of the issues are caused by the bulls contracting bovine herpesvirus whilst working. Testing during the PDS has shown that the few bulls that do breakdown are positive.”

Close up of the preputial damage of one of the bulls previously pictured.

Close up of the preputial damage of one of the bulls previously pictured.

Vaccination program

“Vaccination is only done on bulls before their first joining, as we rarely see any preputial breakdown after the first year. Current available vaccinations are Rhinogard or Bovilis MH + IBR. We have used both vaccines in the past and don’t have a preference as they both seem effective.”

“We include the vaccination with our standard pre-joining protocols, so it is easy to manage.”

Vaccination results

“Since starting vaccinating, we have seen a large reduction in penile breakdown in young bulls and corkscrewing in older bulls. We are still getting a small number of penile breakdowns but no big disasters like in previous years.

“Now that we are aware of the issue, we remove any bulls showing signs of injury or swelling from the joining process to allow them to recover. This year, two bulls out of the four impacted seem to have recovered fully.”

Why was running a PDS on the issue important?

“I think this PDS project was important to run because it gave us the opportunity to gather important information and put some science behind what we thought was happening in the field. We have now proved that vaccination for bovine herpesvirus does reduce the amount of preputial breakdown in virgin bulls, this gives local producers the knowledge they need to develop the best pre-joining protocols for their bull herd and the confidence to invest in better bull genetics.

“Through this PDS I have learned that the bulls that are showing early signs of penile damage can be saved if they are removed from joining and allowed to recover. This has a far better animal welfare outcome for the bull and a better financial outcome for the enterprise.

“MLA’s PDS program is a great tool for grower groups to gather information and share best practice. Practical on-farm demonstrations and trials are always the best way for farmers to learn and share information. I personally enjoy being involved in PDS sites and get great value from seeing how other enterprises manage the issues that we all face.”

Simon’s top 3 tips for producers considering vaccination to prevent bull preputial breakdown:

Vaccinate all virgin bulls at the correct time.

Monitor joining and remove bulls showing damage.

Jump test bulls yearly to ensure that mild infections haven’t led to permanent damage.

For further information, view the "Producer guide: Infectious balanoposthitis of bulls" by Dr Enoch Bergman, Swans Veterinary Services.

Image credits: Thanks to David Riggs (Riggs Australia) for providing video stills for images in this articl.