Bull management

Now is the time to start thinking about bull management.

It takes time to source new bulls, transport them, and do health checks, and it also takes time for bulls to settle into new social groups and recover from unexpected changes and stress.

It takes about 70 days to produce sperm, and over two weeks for it to travel through the male reproductive tract.

Sperm are highly vulnerable to injury from stress, including stress from transport, fighting, nutritional change, environmental extremes, handling and health issues.

Any of these events can cause a bull to ejaculate damaged and inferior sperm for two to three months after the stress event.

Therefore; making sure that any major management event occurs at least two months before the mating period will help to ensure good results.

In your planning you should consider: Selecting your bull team. When you choose your bulls, you need to think about breed, age, size, health status, and calving ease. Acquiring enough bull power. At least three bulls should be used for every 100 cows in the herd, or four bulls for synchrony.

This allows you to be prepared for issues like lameness and injuries if they occur.

Note, this assumes that your bulls are within the ideal age range. Young ( < 18 months) or old (> 4 years) bulls can only be expected to mate 15 to 20 females each – bull power should be increased to compensate. A bull check from your local vet. A recent study done in south west Victoria found that 50 per cent of the bulls tested were infertile or sub-fertile, with half of these appearing physically normal but failing tests for semen quality.

The relative cost of a vet check is extremely small compared to the costs of feeding and maintaining substandard bulls, let alone the cost of excess empty cows.

This should be done at least two months prior to joining to allow sufficient time to replace any failures. Health management. Bulls should be tested and vaccinated for diseases such as vibriosis and pestivirus, especially if sourcing them from other farms.

The introduction of these diseases to a previously-healthy herd can result in mass abortions and other serious concerns.

If you are introducing new bulls it is wise to keep them in quarantine (in a separate a paddock from current stock) for around a week to observe general appearance and soundness; additionally dosing them with a broad spectrum drench. Grouping your bulls. Keep bulls of a similar age together, and socialise them well before the joining period.

Once a group is settled, avoid disrupting it by switching in or out bulls.

Bull management underpins good reproductive performance.

Depending on success rate with AI, your bulls may be expected to get half your herd pregnant, so getting your preseason preparation right is essential.