The value of a prime sexual athlete to beef herds

The value of a prime sexual athlete to beef herds

Beef
RAMP UP FERTILITY: Managing your bull team to maximise herd fertility means getting the most out of what is an important farm asset. PHOTO: Lucy Kinbacher

RAMP UP FERTILITY: Managing your bull team to maximise herd fertility means getting the most out of what is an important farm asset. PHOTO: Lucy Kinbacher

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Bulls can be the missing link in herd fertility

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INVESTING big money in bulls able to drive genetic gain and improved carcase traits means very little if a bull team is not managed to maximise herd fertility.

One of the country's most experienced veterinarians in beef breeding services, Shane Thomson, says bulls are bought for calf delivery first and foremost - there will be no genetics delivered into a herd if the bull doesn't work.

"He's a sexual athlete. He has only one job for the year, it's only for a short time and we need to make sure everything is right so he can perform to the best of his ability," Dr Thomson said.

In a recent webinar hosted by Agriculture Victoria, Dr Thomson, from Holbrook Veterinary Centre, outlined the paths to optimal bull management and reproductive performance - how to get the most out of what is a very important farm asset.

Each cycle of calf age is worth approximately $100, so there is significant value to a bull being highly fertile and achieving high first-cycle conception rates, he said.

"The pregnancy rate of a joining is not what drives profitability, it's where those calves are located within the joining," Dr Thomson said.

"If you have a three-cycle joining period for nine weeks, the calves in the first cycle are probably worth $200 more than those born in the third cycle.

"There is a fair amount of pressure on bulls to get pregnancies at the start of the joining period."

Bull breakdowns

Because bulls are an investment in genetics, the cost of high breakdown rates resulting in delayed conception patterns to an enterprise is significant.

Over the past 20 to 30 years, the rate of bull breakdowns has increased but Dr Thomson said there were some clear explanations for that.

Dr Shane Thomson, from Holbrook Veterinary Centre, explains why managing a bull team correctly is so valuable.

Dr Shane Thomson, from Holbrook Veterinary Centre, explains why managing a bull team correctly is so valuable.

"Our understanding of beef production and profit drivers has improved, so too our pasture management," he said.

"What those two things mean is we are putting more pressure on our systems to be efficient. We are putting weight onto livestock much quicker.

"Joining periods have become shorter - the typical 12 weeks is now down to six-to-eight weeks.

"And joining ratios have increased - the typical one bull per 30 is now around one bull per 50 or 60.

"The work expectation of bulls has gone up and that creates a situation where if the bull breaks down, the cost will be more obvious.

"Also, bulls previously had enough time to recover from many injuries within the joining period for good reason but that's no longer the case."

Up to the job

While components such as structural soundness, semen quality (morphology) and quantity, serving ability and sexually transmitted disease managment like vibriosis and pestivirus all contribute to bull fertility, the producer's ability to manage bulls and keep them up to the job is just as important.

Dr Thomson highlighted four distinct areas of management: purchasing the new bull, management pre-joining, how the team is handled during joining and what happens in the off season.

Tips and tools for good buying are well covered but not so much the rest of the equation.

Research has shown the number of unsound bulls increases with age and the average working life of a bull is around 2.8 seasons.

One Victorian study showed 25 per cent of 2085 bulls over three years of age were unsound for breeding, of which 13pc had locomotion problems, 6pc had penile problems, 3pc low libido and just under 2pc testicular issues and/or poor sperm.

The value of a bull to any commercial enterprise is his ability to deliver pregnancies and be the driver of genetic gain for as long as possible, Dr Thomson said.

"Most of the issues we investigate involve new bulls or bulls used in a single-sire joining situation," he said.

"There are not many good reasons to single-sire join bulls. The only 'excuse' is with seedstock producers but even a lot of those, with increased usage of genomic testing, have down the path of multi-sire joining."

Multi-sire joining modelling shows big differences in pregnancy rates.

Dr Thomson presented a scenario involving 100 cows and two bulls with an eight week joining, where one bull is reproductively sound and stays fit and the other is infertile.

A single-sire joining with no rotations gives a 48pc pregnancy rate. A single sire rotated lifts that to 75pc. But a multi-sire joining will give up to 90pc.

Mitigating risk

Pre-joining examinations include disease prevention, testicular palpation, penile inspection, assessment of structural soundness, serving ability testing and semen assessment.

The BBSE (bull breeding soundness examination) can provide the soundest of bulls at the start of joining but no bull is 100pc safe as most issues are acquired injuries so bulls need close monitoring, according to Dr Thomson.

Along with multi-sire joining, risk mitigation strategies to minimise the negative effects of potential bull failures include a planned induction process for new bulls, not mixing high-risk bulls together, mixing age groups and dominance status, working virgin bulls in smaller paddocks with flatter topography and, very importantly, observation.

Induction involves giving bulls sexual exposure to females so they come into contact with the pathogens in the reproductive tracts of the herd at a time when their workload is not high, and develop immunity prior to the big job.

While some producers are hesitant to put lighter, younger bulls in with the older, heavier ones, the evidence shows fighting behaviour doesn't last long when there is a 200 kilogram weight difference between bulls, Dr Thomson said.

Close observation should happen two to three times a week, depending on age and risk level of bulls.

How do you know they are working?

Look for lameness and evidence of preputial or penile swelling but the most important thing is to understand and be observing mounting behaviours, in conjunction with levels of female oestrous activity.

"If we see bulls riding females a lot it's typically not associated with successful serving," Dr Thomson explained.

Producers should also be conscious that most joining activity happens early in the morning.

Off season

Outside of joining, bulls should be managed in their joining groups, or multiples there of.

Identify and remove fighters where appropriate.

Dr Thomson observing bulls.

Dr Thomson observing bulls.

"If they live together year-round, stable pecking orders are established," Dr Thomson said.

"Again, mix age groups to reduce dominance issues."

Perhaps the most important strategy of the off season, however, is keeping bulls in 2.5 to 3.5 body condition.

The number one problem with mature bulls is being overweight, and this year the issue is particularly bad given the brilliant autumn and paddocks of feed in many parts, according to Dr Thomson.

Ways to keep weight off include having stocking density up, electricity to save fences from destruction, co-grazing, running bulls on lower quality pasture and rotating them out and crash grazing paddocks

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