Annual bull management checklist
1. Current herd bulls
There are several diseases that impair bull fertility either as true venereal diseases or by being adversely affected by the pathogen during the mating period. Many of these diseases can be controlled or managed by an effective vaccination program before the breeding season.
An annual vaccination program should include: botulism, vibriosis, clostridial diseases (5-in-1 vaccine) and ephemeral fever (3 day sickness). Tick fever vaccination may be required in specific circumstances.
Infection of a bull during a short mating season, in particular, can have a serious effect on the herd conception and subsequent branding rates.
Also test for worms and treat bulls as necessary.
Ideal body condition score is 3 (out of 5) for maximum sperm production.
Remember that over-fat bulls can be sub-fertile and excess strain can be placed on their legs and spine.
Check legs, joints and feet for injuries, stiffness and cuts/swelling.
BULLCHECK® or a Veterinary Bull Breeding Soundness Evaluation (VBBSE) covers scrotal and physical examination, semen motility, sperm morphology, and serving capacity (if required).
A vet should do an annual VBBSE, before joining, to identify bulls that are declining in fertility. This is particularly important for single sire herds.
To justify retaining an older age bull in the herd, the bull must be fertile, structurally sound and also be equal to, or better than, the most recent bull replacements for all genetic traits used in selection.
Have you got enough or too many bulls?
The ‘Bull Power’ project found that when bulls met the minimum requirements of a VBBSE, bull percentages of 2.5% did not jeopardise the branding rates on large pastoral holdings where waters were spread out and in large paddock sizes.
2. If you need to purchase bulls
Look at your breeding objective
Identify the traits that are most economically significant.
Talk to your supplier about your requirements (e.g. VBBSE certificate).
Look at BREEDPLAN EBVs and $Indexes to select bulls that match your criteria.
Work through your bull cost per calf and set your price limit and stick to it!
Look at your list of selected bulls and assess/rank for structural and reproductive soundness (based on the VBBSE); temperament and BREEDPLAN EBVs.
Make your purchases.
Make sure you have enough time for your new bulls to adapt to the new environment. ‘Let down’ bulls to working condition before joining if they are in sale or show condition.
Where possible, in-coming bulls should be kept with animals of similar age. Bulls coming from very different geographic and climatic environments should be relocated much earlier than those animals bought from a similar environment to your herd. Even within genotypes, some bulls adapt to more stressful environments more readily than others (the latter being more likely to have their semen quality affected).
Check vaccination history of purchased bulls and vaccinate if necessary.