Motivation for Genetic Improvement

Motivation for Genetic Improvement

The development of a breeding program is often characterized as a series of steps from describing the breeding objective to how genetic improvement will be disseminated throughout the industry. For example:

1. Formulate the breeding objective (what we want to improve);

2. Define the selection criteria and build an Index;

3. Design an animal evaluation system (genetic evaluation – using phenotypes and pedigree information to predict genetic differences between animals);

4. Design selection and mating strategies for animals who will reproduce; and

5. Design system for dissemination of terminal beef genetic improvement from the nucleus to the commercial animals.

In a more simplified manner, if we can answer the following three questions, we are well on our way of designing and implementing a well-structured and sustainable system:

1. Where are we?

2. Where do we want to go?

3. How will we get there?

The first question provides the opportunity to evaluate our production system to identify inefficiencies that may be hindering our ability to be profitable. The second question provides the opportunity to identify how we might disseminate genetic improvement for long-term sustainable improvement. It is the third question that will help us develop the road map to our destination. The road map includes identifying the traits in our breeding objective, how we will evaluate potential breeding animals for genetic merit, what selection criteria we will use to choose candidates, and how we will mate them to maximize genetic improvement. The important point is that formulating a breeding objective and choosing how we will base selection is intimately associated with our genetic evaluation.

At its most basic, genetic evaluation is accomplished through computer services processing pedigree information and performance records for one or more traits. These records are systematically recorded and submitted by breeders. The choice of traits to measure and record involves some collective judgment about what traits are economically relevant, and what traits can be routinely measured in the breeders’ operations (Harris and Newman, 1994). Genetic evaluation is simply the analysis of that data using some defined statistical model(s) to arrive at estimates of the genetic merit of animals in the population. The output from a genetic evaluation is, in the case of beef cattle, an Expected Progeny Difference, or EPD, which measures the difference in performance that is expected from future progeny of a parent. Genetic evaluation procedures that produce EPD for specific performance traits should be considered a means to an end (and not the end). The desired end is an improved economy of producing consumable and desirable livestock products for the benefit of the breeder and the consumer (Garrick and Golden, 2009). Seedstock producers are in business primarily to make a profit, as are their breeding stock customers, who produce food products. Producer’s profits are influenced by consumer’s demand for their products. Purchase of breeding stock involves a cost but can provide a positive influence on the functioning of the system by reducing other expenses or increasing income from output, or both. The producer will be motivated to pay more for breeding stock if given assurance that profit will increase because of these increased costs. Products sold to earn income for a breeder are primarily breeding stock (or alternatively semen). Efforts to improve the value of this product (and thus the income earned) are likely to add expenses due to the extra labor of recording data, registration and computer charges, marketing of intact animals for slaughter, and so on. The breeder will be motivated if given assurance that greater income will adequately cover these increased expenses (Harris and Newman, 1994; Harris 1998).

To summarize, genetic evaluation makes genetic improvement possible. It provides the capability to benchmark individuals within a breed, or possibly different breeds. It is a means whereby the joint investment in recording and selection can be converted to market advantage. It is possible to maximize returns in this process by recording the right traits, and make sensible use of indexing, selection and mating. To maximize the quantity and quality of data recorded so that genetic evaluation can be used most efficiently to add value a well-defined breeding structure is of fundamental importance.