Choosing bulls is the most important breeding decision you make becasuse the sire contributes about 80% of the potential genetic improvement to a herd.
What this means in practice is that the really key decision is which bull breeder you choose.
You must identify a breeder who is making regular genetic progress in the commercial traits which you have decided are most important in your herd. If the bull breeder is not making genetic progress you will not either.
Provided the breeder’s herd is initially of superior genetic merit, you will experience an immediate performance lift when the bulls are first used but then your performance will level off.
The speedboat and water skier analogy used to describe ram selection applies in exactly the same way to bulls. The bull breeder will tow you along at his/her speed of genetic improvement. But you, like the waterskier, can never go faster than the breeder. If you wish to continue accelerating it can only come from the boat towing you.
To ensure you buy bulls which will consistently improve the genetic performance of your herd follow this check list:
1. Gain a clear picture of the breeder’s objectives and satisfy yourself they match up with yours. If the bulls are to last on your farm they should be reared on similar country under commercial conditions which parallel your management practices.
2. Check the selection intensity. Selected bulls should be in the top 15% of the herd for the recording criteria you are using. Replacement heifers should be in the top 50% of the herd.
The stud must be big enough to enable it to make maximum genetic progress. Ensure the stud is either breeding a high proportion of its own bulls or buying from a stud making progress in the characters you want.
3. Sires should be used for only one or two years in the stud before being replaced.
4. Make sure all the relevant records are present, properly prepared and clearly explained.
Developing and implementing reliable methods of comparing the genetic merit of bulls from different herds has been a major concern of animal scientists and breeders for many years. Sire reference schemes, which use semen from a small number of selected bulls as extensively as possible and test the performance of the progeny, provide the most reliable way of establishing bases for comparison.
Artificial Insemination allows you access to sires of top genetic potential and is a powerful method of improving herd performance. Sire reference schemes provide a way of assessing the ranking of bulls chosen for AL
Another technique has been developed to allow comparisons of sires between herds where AI or transferred bulls have been used. This is BLUP (Best Linear Unbiased Prediction), a sophisticated analytical technique which can take accumulated recording data and calculate genetic trends for a given trait, within and across herds.