How to Select the Right Bull for Your Herd

By Dr Duncan Houston

The wrong bull does not just cost one season. It sets your herd back for years.

In practice, bull selection is one of the most underestimated decisions in cattle operations. A bull contributes half the genetics of every calf, but more importantly, he determines fertility, calving outcomes, and long-term herd direction.

The mistake most producers make is focusing too heavily on appearance or sale hype, and not enough on function and fertility.

This guide will help you understand what actually matters when selecting a bull, how to assess risk, and how to make a decision that improves your herd, not just fills a gap.

Quick Answer

The best bull is structurally sound, fertile on examination, genetically suited to your herd goals, and physically capable of working in your environment. Selection should prioritise fertility and function first, then genetics, then appearance. A bull that cannot breed effectively will cost far more than any performance advantage on paper.

Decision Snapshot

• Structurally sound, passes BSE, fits herd goals → strong candidate

• Good genetics but no BSE or structural concerns → moderate risk

• Poor mobility, temperament, or condition → avoid

• Unknown fertility status → high risk purchase

What Actually Matters Most in Bull Selection

There are four core areas that determine whether a bull will perform:

1. Structural soundness

2. Fertility and breeding soundness

3. Genetic merit and performance data

4. Fitness, temperament, and environment fit

What vets actually worry about

Not how impressive a bull looks in the yard, but whether he:

• can physically breed

• produces viable semen

• lasts multiple seasons

• fits the production system

Structural Soundness and Conformation

Structure determines whether a bull can work, not just how he looks.

Key areas to assess:

Feet and legs

• Straight, strong limbs

• Correct hoof shape

• No signs of lameness or instability

Movement

• Free, fluid movement

• Able to cover ground without stiffness

Topline and back

• Straight and strong

• Indicates muscling and support

Hindquarters

• Well-developed muscle

• Important for breeding ability and carcass traits

What matters most

If a bull cannot move well, he cannot breed effectively, regardless of genetics.

Breeding Soundness Exam (BSE)

A BSE is one of the most important steps and is often overlooked.

A proper BSE includes:

Reproductive exam

• Testes, epididymis, penis, sheath

Scrotal circumference

• Linked to fertility and earlier puberty in offspring

Semen evaluation

• Motility

• Morphology

• Concentration

General health check

• Eyes, mouth, body condition, mobility

The key principle

A bull without a current BSE is a risk.

What vets actually see

In practice, subfertile bulls are more common than expected, and the cost of discovering this during breeding season is significant.

Genetics and Performance Data

Genetics determine long-term herd improvement.

Key tools:

Expected Progeny Differences (EPDs)

• Birth weight

• Calving ease

• Growth rates

• Carcass traits

Accuracy values

• Higher accuracy means more reliable predictions

Actual performance data

• Growth records

• Health history

• Fertility outcomes

What matters most

Genetics should match your production goals, not just be “high performing” in general.

Fitness, Condition, and Temperament

A bull must be physically and behaviourally capable of doing the job.

Key factors:

Body condition

• Ideal BCS 5 to 6 out of 9

• Too thin reduces fertility

• Too fat reduces mobility

Mobility

• Must move easily and cover pasture

Temperament

• Calm and manageable

• Not aggressive or unpredictable

What vets actually worry about

Temperament issues and poor mobility are major causes of early culling.

Matching the Bull to Your System

A good bull in the wrong system becomes a poor investment.

Consider:

Environment

• Climate adaptability

• Breed suitability

Feeding system

• Match frame size to available nutrition

Calving management

• Choose calving ease bulls where labour is limited

Real-world insight

The best bull is not the best animal in the sale.
It is the best fit for your system.

Severity Framework: Risk of a Poor Bull Choice

Low Risk

• Passed BSE

• Structurally sound

• Matches herd goals
  → High confidence purchase

Moderate Risk

• Good genetics but limited fertility data
  → Requires careful monitoring

High Risk

• No BSE

• Structural or mobility concerns
  → Likely performance issues

Critical

• Known fertility or soundness issues
  → Avoid entirely

How Bull Performance Plays Out Over Time

• Early season → active breeding behaviour

• Mid season → sustained fertility and coverage

• Late season → fatigue or performance drop if not fit

What matters

A bull must maintain performance across the entire breeding period, not just start strong.

When Should You Be Concerned?

• Low pregnancy rates

• Uneven calving spread

• Bull showing lameness or fatigue

• Reduced mating activity

These are signs the bull may not be performing.

What To Do Before Buying a Bull

1. Inspect structure and movement carefully

2. Confirm a recent BSE

3. Review genetic data and EPDs

4. Assess body condition and temperament

5. Match the bull to your production system

Do not:

• Buy without a BSE

• Ignore mobility issues

• Over-prioritise appearance

• Choose genetics that do not fit your system

The rule to remember

Fertility first, function second, genetics third.

Common Mistakes

• Buying on appearance alone

• Skipping fertility testing

• Ignoring feet and leg issues

• Choosing bulls too large for the feed system

• Not matching genetics to herd goals

Prevention: Setting Your Breeding Program Up Properly

• Perform BSEs before every breeding season

• Monitor bull condition regularly

• Rotate bulls if needed

• Track pregnancy rates and outcomes

• Replace underperforming bulls early

FAQs

How important is a BSE?

Essential. It confirms fertility beyond appearance.

Can a bull look healthy but be infertile?

Yes. This is more common than many expect.

Should I prioritise genetics or fertility?

Fertility always comes first.

How often should bulls be tested?

At least annually before breeding.

What is the biggest mistake in bull selection?

Ignoring structural and fertility issues.

Final Thoughts

Bull selection is one of the highest-impact decisions in cattle production.

A good bull improves fertility, consistency, and herd genetics. A poor bull quietly reduces performance and profitability.

The key is not choosing the most impressive animal, but the most functional and reliable one.

If you want help reviewing a bull, interpreting BSE results, or matching genetics to your herd goals, ASK A VET™ can support your decision with practical, real-world guidance.