Managing bulls for reproductive success

08 April 2016

Maximising the number of calves on the ground in a defined joining period is one of the primary objectives of a beef breeding business.

However, according to Coolac veterinarian, Tom Graham, many producers miss this opportunity by failing to forward plan and manage joining periods effectively.

“A lot of producers already know the theory but so many fail to put it into practice,” he said.

Tom, who is also a beef producer, will be speaking on bull management, health and joining periods at a ReproActive workshop at Morundah, NSW, on Monday 18 April.

He believes one of the most common and costly mistakes producers make is being too complacent about bull and herd health leading up to and during the joining period.

“Most producers, including myself, have experienced bull failures but instead of saying, ‘the bull broke down that’s why I’ve got so many empty cows’, we need to accept fault and address it as a management failure of something we could have controlled,” he said.

Bull Breeding Soundness Exams

Tom believes producers should make an annual practice of getting their bulls examined by a veterinarian for fertility, soundness and ability to work six-to-eight weeks prior to joining.

It is also a good time to give the Vibriosis vaccine, providing bulls with maximum coverage during the joining period.

Once out with the herd, bulls should be inspected closely, at least twice a week (daily even better), during the first three weeks of joining.

“That means casting an experienced eye, watching bulls work and looking for penile dysfunction or  injury, not just driving past and saying ‘he’s there’,” Tom said.

“After that period, at least 65% of females should be in calf so checking bulls, although still important, is less crucial.”

Tom estimates between 8-10% of young bulls are injured during the initial three weeks.


Unfortunately, when it comes to vaccinating bulls, particularly for Vibriosis,Tom believes there are few producers who actually do this.

“In my opinion, Vibrio vaccine just isn’t used enough; neither is Leptospirosis vaccine, usually administered as 7 in 1.

“Leptospirosis is not only a costly reproductive disease, it’s also a human health risk.

“Producers can administer it to pregnant females at pregnancy testing.”

Tom said monitoring and testing for Pestivirus is also important and said in his service area it was very rare to find a naïve (Pestivirus-free) herd.

He recommends seeking veterinary advice, testing and, at the very least, vaccinating maiden heifers but for a better outcome, aiming to blanket vaccinate the entire herd.

Joining periods

The decision of when to join should be made ‘in-synch’ with the environment so it coincides with females’ nutritional needs pre and post calving.

“For an autumn calving production system, I’d recommend females are above body condition score 3.5 (scale 1-5) to ensure they re-join on time and can feed a calf as they approach winter,” Tom said.

“Spring calving herds can afford to be 0.5 to 1 score less.”

Tom believes heifers should be joined for six weeks and cows for nine.

“I don’t mind if heifers are joined for longer as long as late calvers are identified,” he said.

“If they are late to join first time round, they will always be late.”

Bulls should be removed from cow herds as soon as the joining period is over.

“Economic modelling has shown that tighter joining periods with some empty females are more profitable than, say, a 20-week joining period and no empties,” Tom said.

Bull selection

Producers need to select bulls with Estimated Breeding Values that meet their market goals, however, Tom emphasises the importance of structure and critical assessment before buying to ensure bull longevity and that only positive structural traits are being passed on to the herd.


Under-utilised is how Tom describes the insurance of bulls, particularly for the first six months of their working life.

“Most bulls, if they are going to break down, will do so during this period,” he said. “With the price of commercial bulls now, I think this a worthwhile investment.”

Learn more

The ReproActive workshop will also feature Elders Senior Livestock Production Advisor Rob Inglis speaking about critical mating weights, weaning management and providing yard demonstrations of condition scoring and assessment.

Zoetis Australia’s Veterinary Operations Manager Natalie Robertson will cover reproductive disease management through vaccination.

When: Monday, 18 April
Where: Boonongo, 2500 Urana Rd (Federation Way), Morundah, NSW
Cost: $40, includes course materials, refreshments, lunch 
To register online: by April 17 for more information and directions.
Contact: Tom Graham T: 0422 050 019 E: 
Resources: For more information on improving reproductive efficiency visit the More Beef from Pastures module

Back to News

Join myMLA today

One username and password for key integrity and information Systems (LPA/NVD, NLIS, MSA & LDL).

A personalised online dashboard that provides news, weather, events and R&D tools relevant to you.

Customised market information and analysis.

Learn more about myMLA

myMLA Sign Up

Already registered for myMLA?

Sign in here