Author: Elizabeth Henning, Chair ADGA Genetic Advancement Committee
This article will focus on the steps a breeder needs to take to obtain the genetic information on his/her own goats that will enable use of the numbers to make genetic progress.
Two terms used in genetics that are important to understand are “phenotype” and “genotype.” Put simply, phenotype is what we observe (e.g., coat color, rear udder height, butterfat percentage) while genotype is the entire genetic package of any given individual that was inherited from its parents.
For many years, ADGA has been accumulating the phenotypic information that is used to generate the genetic information on which the “numbers” are based. Before dairy goat breeders began to use the DHI (Dairy Herd Improvement) Program, many kept “barn records” to document the milk production of their does. When DHI became available to dairy goat producers, in addition to official documentation of milk production, we were also able to document the butterfat, and later, protein content of the milk produced by does enrolled in the DHI program. With the development of ADGA’s Linear Appraisal program in the late 1980’s, type information (the 13 linear traits and final score) could also be incorporated into the genetic information being accumulated.
It is the data from the DHI and Linear Appraisal programs that provide the basis for generating PTA’s (Predicted Transmitting Ability) or the genetic merit an animal is expected to pass on to its offspring. For young sires without offspring, this is expressed as an ETA (Estimated Transmitting Ability.) When we decide our breedings, there are many, many things that we might consider, depending upon our goals as a breeder. These considerations may or may not include a desire to improve production and/or type. However, for those who are interested in genetic improvement in both production and type, there are steps we can take to help us achieve those goals.
First of all, we need to have as much genetic information as we can obtain about the animals currently in our herd. This involves examining the “numbers.” If our does/bucks have DHI and Linear Appraisal records, OR if our animals have that information “close-up” in their pedigrees, we can start there. Relevant milk production and type “numbers” can be evaluated as described in Mr. Baden’s article and also in the Performance Programs section of the ADGA website. In order to be able to evaluate the results of current breeding decisions, it will still be necessary to obtain the “numbers” on offspring. This requires participation in the DHI and Linear Appraisal programs. Only these programs will generate the “numbers” for YOUR animals.
Secondly, don’t expect instant results. Since genetic evaluation information is dependent upon existing records, if you are starting with animals that currently lack performance data, a few generations will be required to generate meaningful data. The pace of improvement can be accelerated by using young sires with high ETA’s or proven sires with high PTA’s, but it still won’t happen overnight. Instead of expecting positive numbers at once, expect to see improvement from generation to generation. This practice can also be used to evaluate your current herd when examining their performance pedigrees.
Finally, be persistent. While available genetic evaluations control for (among other things) age, time of freshening, and geographical factors, individual management and the nature of genetic transmission will also have an impact upon the perceived success (improvement in phenotype) of any individual mating. The genetic potential of that mating may not be expressed phenotypically in the first generation, but perhaps will in subsequent generations.
The bottom line is to “get the numbers.” There are several options available in the DHI program that will provide you with production data. You will also receive a discount by enrolling to participate in both DHIR and Linear Appraisal, and the ADGA PLUS program provides you with discounted DNA testing fees to help safeguard your genetic investment and contribute to the dairy goat DNA database.
Enrollment in these programs may end as early as January 31, 2015,, depending on the options you choose. Contact the ADGA office or visit the Performance Programs section of the ADGA website for further information. You’ll soon be on your way to genetic success!