Purchasing a bull can be an expensive process, but the value that he brings to your herd can be worth far more than his initial cost. It is important to consider what you want from your bull before choosing him, and once you have chosen, to ensure that he is healthy and fit for purpose.
Estimated breeding values
Estimated breeding values (EBVs) are a measure of the genetic potential of a given sire. There are a number of traits which are measured (see below) and some results are combined to given indices to meet specific breeding objectives. EBVs are designed to remove the effect of nutrition, and management and environment to give a best estimate of genetic performance of a bull. Look for accuracy values of greater than 75%.
Understand your market
Your production system will govern which traits you should be identifying as important. For instance, beef producers selling progeny at weaning, Calving Ease (direct), Birth Weight, Muscle Area and 200 Day Growth would be important.
For those producers finishing stock, 400 Day Weight is paramount and Fat Depth must be considered. Those breeding their own replacements need to also consider Calving Ease Of Daughters, 200 Day Milk, and Scrotal Circumference. Scrotal circumference is closely related to the fertility of daughters and they will reach puberty earlier.
For dairy herds considering a beef bull to maximise the value of surplus calves, looking at EBVs is also important. Priorities for Calving Ease, Low Birth Weights, and Shorter Gestation (Calving Value) are important to reduce costs associated with dystocia and also to reduce calving interval. In addition if the progeny are to be sold as young calves then 200 day weight is also important.
Breeding for specific objectives enables strengthening of current herd genetics’, and improvement in areas which are deficient when breeding replacement beef heifers. Dairy producers, selecting semen for artificial insemination of cows for replacements use PTAs (predicted transmitting abilities) or proofs to advance herd genetics. This will ultimately enhance herd profitability.
Ensure breeding policy forms part of your herd health plan discussion with your vet.
A fertile bull should be able to get 90% of 50 breeding cows in calf within 9 weeks. Producers with a tight calving period, including block calving dairy herds using a sweeper bull, need to know that the bull is going to achieve those targets. A subfertile, infertile or sterile bull will not achieve this and will result in costly extensions to calving interval.
Ask your vet to perform a pre-purchase examination. This usually consists of a thorough physical examination, including assessment of internal and external, sex organs, and a semen test. Your vet will obtain a semen sample via electro-ejaculation, and will assess the volume, density, motility of the sample and assess sperm for defects. This should be performed within a few weeks of the start of breeding to reduce the risk of a change of status.
A semen evaluation does not assess libido or mounting ability, and therefore does not confirm the ability of the bull to breed.
Try to avoid bringing in disease. For closed herds this is often the only animal coming onto the unit, and the herd may be relatively naive (susceptible to disease).
Establish from the vendor, their Johne’s status. This is difficult to test for in young animals, so the status with the herd of origin is of more use. Other infectious diseases, such as Leptospirosis, BVD, and IBR should be tested for, or vaccination status should be established. Campylobacter is a venereal disease causing infertility and is spread by bulls. Have your bull tested for this before he is allowed to serve any cattle. Quarantine your bull on arrival and treat him for internal and external parasites; fluke, worms and lice, and observe for any signs of disease.
Find out the diet that the bull has been fed to ensure as smooth a transition as possible and promote rumen health.