Bull check: the top tips for ensuring your bulls are ready for joining

With spring calving underway on many beef cattle farms, and spring bull sales in full swing, it won't be long until the next joining period.

Bulls across the country will return from their holidays to join breeder mobs, some tasked with getting upwards of 50 cows in calf.

Much focus will be given to cow nutrition and management over the coming weeks to ensure breeders are at optimum fertility for joining.

However, as they are responsible for 50 per cent of the joining equation, bull nutrition and management is equally important.

While many producers may be comfortable with leaving their bulls to pasture, un-yarded and un-checked until joining day, a little bit of extra care now could go a long way to improving joining results.

Stock & Land has detailed some of the top tips for bull preparation this spring.

New bulls

While the purchase of a new bull should inject new and better genetics into a herd, it is crucial that all bulls are bought at least six weeks before joining.

This gives a bull the chance to acclimatise to his new environment and allows for a quarantine period.

Producers should find out exactly what vaccinations the bull has received at his stud of origin and if he needs any further vaccinations.

Quarantining allows for any unusual diseases to be detected in the bull and prevents their introduction to the full cow herd.

Fertility testing

Fertility testing a new bull is a strong recommendation, and even fertility testing older and experienced bulls can be of benefit.

Such a test, completed by a vet in advance of the joining period, can give a farmer peace of mind that all of their bulls are in working order.

It is a little-known fact that one in four bulls is either infertile or sub-fertile, or, in the case of a young bull, they may still be pre-pubertal.

Some early-maturing beef breeds will reach puberty at 12-14 months, whereas later-maturing continental breeds may be 16 months old before they reach puberty.

There are multiple reasons a bull may become infertile or sub-fertile.

These include sickness, high temperatures, nutrition or injury.

A vet carrying out a fertility test will also physically examine the bull to make sure he is fit for breeding.

This examination can also be done by an experienced cattle person, if required.

When it comes to the bull's testicles, an ideal scrotal circumference is generally 34-35 centimetres or more.

Such a size is a reliable indicator of fertility and semen production, though the ideal size varies by age and breed.

Larger scrotal circumference correlates with higher semen quality and greater reproductive capacity, with lower circumferences (under 30cm) often indicating low-quality semen and lower conception rates.

While producers can do their best to examine the bull's testicles, a vet is more qualified for this task.

They can check the bull's testicles for any damage or blockages, again an indicator of their fertility and potential joining success.

Feet and legs

Producers should inspect each bull's feet and legs before the joining period.

These are perhaps the most important part of a bull's anatomy during joining as he will have to cover large distances following in heat cows during joining.

Good feed and legs will ensure the bull is physically sound and able for mating.

Farmers should closely watch each bull to ensure he is walking smoothly, ensure his feet are even and that they do not require pairing.

Any young bulls with poor feet should be avoided, as this will likely be an ongoing issue as the animal ages and becomes heavier.

Condition score

Ensuring bulls have adequate nutrition in the run-up to and during joining is another factor that will improve scanning and calving percentages.

Bulls should always be fit, not fat, before joining.

The ideal body condition score for bulls before joining is 3.0 on a 1-5 scale.

This ensures that the bull has sufficient energy and fertility without being overweight, which can impair thermoregulation and fertility.

A score of 3.0 is a critical benchmark, while 2.5 is the minimum acceptable score, and anything above 3.5, especially 4.0 or 5.0, indicates an overweight bull that risks infertility and reduced activity.

Farmers can learn how to correctly body condition score their cattle here.

Workload

When planning to join, farmers should also ensure they do not overwork bulls, particularly young bulls.

Young bulls should be introduced to a small number of cows to start off with, and this should then be gradually increased.

This avoids the bull being overworked.

Young bulls are still growing, so they will have an extra drain on their energy.

Any major loss of body condition as a result of being overworked could have an impact on the bull's fertility.

Farmers are advised that a young bull should be run with the same number of cows as he is months old.

For example, a 15-month-old bull can be joined with 15 cows or a 20-month-old bull with 20 cows.

A mature bull, usually over two years old and proven fertile, can typically service 30 to 35 cows in a standard joining period, with some experienced bulls potentially handling 60 cows.

Key factors influencing this capacity include the bull's age, physical condition and libido.

Monitoring

Monitoring bull performance once joining has commenced is also important.

For the first few weeks, producers should monitor each bull closely to be sure he is interested in and successfully mounting and serving cows.

It is good practice to introduce a younger bull to one or two cows that are in heat before putting him with a larger group of cows, just to be sure he is doing the job.

Farmers should also try and jot down when a sample of cows, particularly those that first come into heat, are joined, and watch out for repeat joinings.

A cow's breeding cycle, or oestrous cycle, averages 21 days (18-24 days) and includes a heat period of between six and 30 hours.

Repeat joining rates vary from herd to herd, and the condition and nutrition of the cows.

If a high number of cows than normal are observed to repeat join - that is, not go in calf following their first joining with the bull, bull fertility should be examined.