Breeding Bull Management

Bulls are a significant investment for breeding herds. The right bull selection will have a major effect on herd fertility. A little time and attention to make sure your bulls are fit, free from disease, and actively working is well worthwhile.

Before mating, undertake the following preparation on all bulls:

  • have a veterinary bull soundness evaluation done
  • feet — trim claws if overgrown, check for corns
  • booster vaccinations — vibriosis, seven-in-one and three day sickness, botulism and pestivirus
  • parasites — treat for worms, liver fluke and lice
  • assess body condition — if too fat it limits mobility and too thin limits durability, change feed and supplement if required.

Tips for Preparing Bulls For Joining

In many pasture beef operations, the bull goes in with the cows and nature does the rest…right? Unfortunately, I am sure I will see and hear plenty of stories during summer at pregnancy scanning and next spring at calving, of disappointing results.

Most operators know that for cows to fall pregnant they must be in good condition and on good nutrition, with adequate time to have recovered from the previous calving. First calf heifers need to have reached their critical mating weights. But there is the other half of the equation – the bull.

A lot can happen in a year, and just because a bull proved himself last year does not automatically mean you can set-and-forget. Injuries, body condition, fitness, and illness can all play a part in his success.

breeding bull

Does Your Bull Need A Tune-Up?

Be proactive and check the bull early to give yourself time to treat problems or find a replacement. He must have good feet and legs and appear strong in his gait with no signs of lameness. Make sure you have appropriate facilities and can keep yourself safe when handling him, check his reproductive apparatus. He must have both testicles present, and the testicles should be large (yes, size does matter), similar in size to each other, and firm to the touch without lumps, bumps or scabs. The penis should be checked for any sign of injury or deviation. He should be in good body condition (he will be using a lot of additional energy during mating) but should not be over-fat. Make adjustments to his nutrition in good time to gain or lose weight before joining.

Many smallholders don’t keep a bull of their own and it is common to loan a bull from a larger enterprise or neighbour. Ask the owner about the bull’s soundness as outlined above. Ideally view the bull before agreeing on the loan arrangements. It is imperative to consider biosecurity when loaning a bull – complacency can lead to failures in pregnancy and could have long lasting implications. There are several common diseases that can lead to infertility of the bull or the cow. If you don't have safe restraint facilities on your property, consider asking to have the bull vet checked and disease tested on the owner's property before you loan him.

I recommend talking to your vet or advisor about vaccination programs (with or without prior testing) for pestivirus, campylobacter and leptospirosis. Vaccine programs can take several weeks to take effect so there is no time to lose.

For joining to be effective the bull needs to be producing fertile sperm. If an illness or stressor has rendered the bull temporarily infertile it can take more than 6 weeks for the sperm to be functional again. The only way to be sure of sperm fertility is with a morphology and motility test. A bull breeding soundness evaluation service can be provided by a livestock vet with a special interest in reproduction.

When the bull is introduced to the cows watch to make sure he is interested in doing the job and is seen to be working. Keep looking out for any signs of injury, lameness or illness of the bull. These can affect his physical ability or desire to breed, as well as sperm fertility. If something happens you need to be ready to implement a Plan B such as replacing the bull or changing the length of the joining period.

What is a Bull Breeding Soundness Evaluation?

Breeding soundness examinations ensure your bulls meet the minimum standards for fertility and reproductive health. The BBSE is a uniform method of assessing a bull's likelihood of accomplishing pregnancy in an appropriate number of open, healthy, cycling cows or heifers during a defined breeding season. The BBSE includes a semen exam to evaluate sperm motility and morphology as well as a physical exam. The bull is evaluated for overall structural soundness, reproductive development, testicular size and health, and the physical characteristics of the bull including mobility and athleticism in the pasture.

Assessing Bulls For Joining

What to look for when selecting bulls for breeding:

Conformation and feet
Inspect knees, hips and feet—very straight or very angular conformation can result in early joint damage and arthritis. Watch the bull walk around—stringhalt (locking of the kneecap) is sometimes seen in bulls with Bos indicus content. Look for bulls that stumble on uneven ground as it usually indicates some musculoskeletal problem. Check the feet carefully. Fibromas (foot warts) are common in many bulls. Unevenly grown claws usually indicate uneven weight bearing and may indicate joint pain. Corkscrew claws and scissor claws also appear to be heritable and should be avoided. Avoid inspection in muddy yards as it will be difficult get a good look at the feet.

Reproductive organs
Watch for sheaths that hang low and close to the ground as they can be easily injured. Testicles should be free of lumps or swellings and equal in size. Bulls with a high scrotal circumference have greater fertility and have daughters who are more fertile. Aim for 29 cm at two years of age in Brahmans and 27 cm at 15–18 months of age for British and European breeds.

Young bulls (18 months to two years) are quite fertile, but inexperienced. By using bulls earlier, you can increase the working life and uptake of the new genetics and save money, but they are also prone to more injuries because they mount more often than older bulls.

Be careful about grain-fed bulls. They may not do as well on an all pasture diet and need time to adapt before joining. Bulls should not be more than condition score three.

If it is possible, observe the bull trying to serve. Spiral deviation and persistent frenulum are two common penis problems that can only be detected with the penis extended. Spiral deviation is seen most commonly in polled breeds (up to 20 per cent) and can increase with age.

Bulls can be very dangerous, so selection on temperament is important. Bulls will also influence the temperament of their offspring.

Adapted from content by district vets Phil Kemsley and Lou Baskind.

For more information, download the Beef Cattle Health & Husbandry Guidebook PDF, 5039.46 KB

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