3-Buy the right bulls
Buy the right bulls (or semen) to maximise progress toward enterprise profit (the breeding objective) and avoid inbreeding.
Guidelines for buying the right bulls
The purchased bulls, or semen for an artificial insemination program, need to provide the best value for the financial outlay. Regardless of the breeding program, the genetic value of a bull to an enterprise is based on how well its individual attributes fit the herd’s breeding objective.
EBVs are always the best estimate of the genetic potential for a trait. Accuracies that accompany the EBV value indicate how much information has been recorded for a particular animal for the reported trait. The accuracies improve with the more information collected (see Tool 4.4).
Use EBVs related to the traits identified in Procedure 1 to select the best bulls for the breeding program, as they are important to the breeding objective
Measure the value of a bull by its ‘fit’ with your breeding objective
Relate the price you can ‘afford’ for a bull to the bull’s potential earning capacity. The most profitable bulls for your herd will be those with the greatest difference between predicted earning capacity and purchase price. These bulls may not always be those with the highest genetic merit.
Use the $Index value for all bulls you are considering to compare their prices. The index value is in dollars per cow mated. As a guide to a bull's value, multiply the index value by the likely number of cows he will be mated to in his working life. For example, the bull will be used for four years over 50 cows per year (200 cows). This value is a good guide for comparing bulls. A bull with an index value of 100 compared to a bull with an index of 50 is worth $5,000 extra (ie 200 cows x $50 index points x 0.5). Multiply by 0.5 because only half of the value comes from the bull. This calculation doesn’t set the price, because it depends on the average for the sale, which depends on many other factors (see Tool 4.5 for a guide to valuing your bull purchase).
Use this information to select the bull with the highest genetic value for your herd’s breeding objective from those with the greatest difference between estimated earning capacity and purchase price. Tool 4.5will assist you to avoid two common pitfalls when buying bulls:
- paying too much for the apparent ‘super bull’ when the second best bull is better value
- paying too much for the worst bull in a sale catalogue because he was less expensive.
Ensure that your bull supplier is accurately recording all possible traits associated with traits that are economically important to your breeding program. If a bull breeder is recording all important traits, it will be reflected in the accuracies of the EBVs presented (see Tool 4.4). As a guide, young bulls should have all EBVs displayed with accuracies between 50–60% for weight traits. Traits of lower heritability will have lower accuracies. (If EBVs aren’t displayed, it generally means that trait hasn’t been recorded.)
Choosing a bull is the decision point at which inbreeding should be considered. In commercial herds, a rule of thumb is to avoid successive bull purchases that have a common parent. Inbreeding is a major impediment to the genetic progress of bull breeders, and mostly they try to change genetic lines on a regular basis.
Check bulls for structural soundness at purchase and annually before mating
Remember that the physical ability of bulls to sire many calves is a primary consideration. The selection of bulls for maximum fertility based on structural soundness and libido are discussed in Procedure 1 of Module 5: Weaner throughput. Management can also play a large role in bull fertility. Prevention of infectious reproductive diseases is outlined in Procedure 1 of Module 6: Herd health and welfare.
What to measure and when
Predict the value of bulls for improving enterprise profitability
When a new bull purchase is being considered, and before mating each year:
- assess the genetic merit of prospective bull purchases
- estimate the earning capacity of bulls based on the index value and the projected pattern of use (number of cows per year × number of years used) (see Tool 4.5)
- assess structural soundness of the bull battery
- assess the accuracy of information given to you by your bull breeder (see Tool 4.4 to find information that is recorded on sale bulls and the subsequent accuracies associated with the EBVs).