Grab the bull by the horns
Are you using bulls with your herd this year? Here's a couple of top tips of things to consider when selecting your bulls (first tip: don't get bulls with horns, and don't grab them if they do!).
Bull power - make sure you have enough
Ideally you would want to have two teams of bulls at a ratio of 1:30 non pregnant animals, with a couple of spares on a rotation policy. For heifers a ratio of 1:15-20 using an "all in" policy. However, never have less that two bulls in a mob at all times.
Remember: if you are doing a synchro programme (such as CIDRs or PG) you will need increased bull power to cover their returns.
Selecting a bull
Make sure they are sexually mature (usually at least 15 months old) and that they are physically big enough to successfully mate your cows and heifers. However, we don't want them too big either - a rough rule of thumb is that they shouldn't be any more than 100kg heavier than the cows they are mating. They should be in good condition score (4.5-5.5), particularly in the 2-3 months prior to mating, as this is when sperm production occurs.
Bulls that are three years old and younger will typically have less temperament and management issues, and have a lower likelihood of existing feet, back and penile injuries.
Virgin bulls are less likely to have venereal diseases to introduce into the herd. For non-virgin bulls consider testing for these. Bulls should be tested clear of BVD, EBL, IBR and TB, and have a vaccination history for BVD and Leptospirosis.
Bulls should be easy calving, and if considering BVs look for low birth weight and high calving ease scores.
The bulls should be sources from a farm that fits with the bio-security policy of the farm and you should have a knowledge of prior movements. They should arrive on farm a minimum of two weeks before they are needed to recover from trucking, and sort out their pecking order before being put with the herd.
Managing the bulls
Monitor the bulls for injury or illness. Remember than infection, injury or antibiotic treatment can impact on sperm quality for a month or longer, which will make them ineffective.
Train them not to enter the concrete yard or dairy shed
Observe them to make sure they are serving the cows correctly, and if they aren't remove them.
Remove any bulls exhibiting stalking or aggressive behaviour, as this is a risk to on farm health and safety.