Sire development programs have been the primary source of genetic improvement in the dairy cattle industry.  Over the last 20 years they have doubled milk production and helped improve type. Based on the experience and information from dairy cattle and armed with a program modeled after the successes of that industry, dairy goats can expect similar improvements. The ADGA Sire Development Program (ADGA-SDP) is a computerized mathematical screening of all young bucks, generated when they are registered.  Those bucks with sufficient available production and type appraisal pedigree data are evaluated to determine their relative genetic worth.  Production and type data for this evaluation are obtained from the United States Department of Agriculture (USDA) through the USDA Sire Summaries for Production and Type.  Relative genetic worth is expressed as Estimated Transmitting Ability (ETA) which is an estimate of a buck’s potential genetic ability.  The ETAs are then ranked by breed and compared to previously determined selection criteria to see which bucks qualify for the ADGA-SDP.A sire development program is needed for several reasons.  By the time superior bucks can be identified, they are often dead or are uncollectible and, therefore, are unable to pass on their superior genetics to large numbers of offspring.  Most bucks are bred to too few does and in too few herds to get sufficiently accurate data to make genetic progress.  In addition, too many of the bucks presently used have little chance of being genetically superior for either production or type. 

Definition 

Four pieces of data are required to provide an ETA for a buck, two for production and two for type.  One each of the production and type values come from his sire and one each from his dam.  A young buck whose immediate ancestors do not have genetic evaluations for both production and type through the DHIA production testing and ADGA Type Appraisal programs is unable to be evaluated for the ADGA-SDP.

The ADGA Sire Development Committee will set ETA qualification levels and review the annual release of the USDA Sire Summaries for Production and Type.  These levels are set to insure that the bucks which qualify have a high probability of being genetically superior without unduly restricting the number of qualifying bucks and without having an adverse effect on genetic diversity or breeder participation.

The ADGA membership will be informed in several ways about bucks that qualified for the ADGA-SDP.  The owner of the buck will be informed by the ETAs 2:1 and 1:2 printed on the production pedigree that is furnished at the time of registration. Production pedigrees containing individual ETA information are available for a fee to the general membership on any registered buck.  A list of qualifying bucks and their ETAs will be made available annually to the general ADGA membership.

The ADGA-SDP identifies potential genetically superior bucks as young as possible.  Ideally, qualifying bucks are then progeny tested the first year.  It is up to their owners to get them used so that daughters will be produced in as many herds as is possible.  The various herds are under different management and reflect different environmental conditions.

Research indicates that management and environmental differences account for about 80% of the differences in milk production between herds and genetic influences account for about 20% of the differences.  When daughters are spread out among several herds, management and environmental influences can be mathematically removed by statistical procedures on large computers and the remaining genetic influences can be evaluated.  A daughter on production test and appraised in each of 15 herds is the goal to attain a reasonable first evaluation of a young buck.  Buck evaluations are possible with fewer daughters, but as the number of daughters increases, so does the accuracy of the evaluation.  The production tested and appraised daughters will provide actual genetic data with which to calculate a buck’s true genetic worth as expressed in the USDA Sire Summaries.

Participation 

The ADGA-SDP is flexible and is designed to benefit all dairy goat breeders.  Breeders may prove their young bucks by selling semen to other herds, by natural breedings, or by selling or trading daughters of those bucks.  Groups of local breeders may cooperate to prove bucks by sharing several bucks among their herds.  Breeders may use the ADGA-SDP evaluations to help them select bucks or semen which has a high probability of genetically improving their herds.  Breeders may plan matings to create bucks with high ETA values.  Breeders who are fully involved in the ADGA-SDP would also be enrolled in the DHIA production testing program and take part in the ADGA Type Appraisal program.

In order to furnish genetic information for the proofs of the young sires, owners of daughters of the young ADGA-SDP bucks also need to be on DHI test and to have those daughters appraised.  The daughter should be bred to freshen as yearlings to generate data on their sires as soon as possible.  In order to generate sufficient data for Sire Summaries, it is important to use each buck in many herds and use several bucks in each of those herds, ideally including at least one buck that has been used very widely.  When bucks are used in this manner, direct and indirect comparisons can be made between all bucks being evaluated for inclusion in the USDA Sire Summaries.  While it may be possible to get daughters in several herds using natural service in densely populated goat areas, the most feasible way to put daughters in many herds in a wider geographic area is by the use of artificial insemination.  Genetically superior bucks will contribute significantly only if their genes can be spread throughout the general population.

Irrespective of a buck’s ADGA-SDP qualifications, the ultimate genetic value of that buck is not his ETA, but his Production/Type Index (PTI).  This is because the PTI value as published in the USDA Sire Summaries is generated from actual production and type data from daughters of the buck and reflects his true genetic transmitting ability.  The ETAs used in screening for the ADGA-SDP are estimates of a young buck’s transmitting ability based on production and type information of his ancestors.  ETAs are the best indicators of the genetic value of a young buck until such a time as his daughter information becomes available through PTIs. 

Methodology 

Parents of young bucks are evaluated on the basis of two genetic Production/Type Indexes (PTIs).  One PTI emphasizes production over type in a 2:1 ratio, while the other PTI reverses emphasis in a 1:2 ratio, in effect, favoring type over production.  ETAs of young bucks are calculated from the mathematical average of the PTI information of their parents.

The computer calculations which produce ETAs for all registered bucks are straightforward and can be hand-computed by anyone wishing to find ETA values on specific bucks.  ADGA members currently have available all of the information needed to calculate ETAs by hand.  The latest genetic production data on sires and dams are available on DHI individual cow record sheets.  Annual USDA genetic production and type evaluation information in the form of PTIs is available on both sires and dams through the ADGA Performance Volume.

Hand calculated ETAs can assist us in several ways.  They allow us to know ETAs in advance of the arrival of production pedigrees.  ETAs can be used to plan matings or they can be estimated for a buck we may be considering as a herd sire.

The ETA calculations used in the ADGA-SDP are shown in the following procedures.  When PTIs are available for both sire and dam, go directly to Step 3 to calculate ETAs.

Step 1

 Convert genetic milk yield to Fat Corrected Milk (FCM) for both sire and dam.

                                                           (132.06) x (PTAM) + (4964) x (PTAF)

                             FCM             =     ——————————————–

                                                                          (49.64) x (2.66 + BAFP)

where PTAM = Predicted Transmitting Ability for Milk yield (formerly known as PDM for bucks and DIM for does)

          PTAF  = Predicted Transmitting Ability for Fat yield. (formerly known as PDF for bucks and DIF for does) 

NOTE:  PTAM and PTAF (or PDM and PDF) for bucks can be obtained from the ADGA Performance Volumes or USDA Sire Evaluation Summaries and PTAM and PTAF (or DIM and DIF) for does (also known as CIM and CIF) can be obtained either from the ADGA Performance Volumes or DHI individual cow record pages.

BAFP =   Breed Average Fat Percentage, see most recent guidebook for fat percentages by breed:

Step 2

 Calculate Production/Type Indexes (PTIs) for both sire and dam for both 2:1 and 1:2 weighing factors.  The four PTI values resulting from the calculation are one number each for the sire and dam favoring production over type and one number each for sire and dam favoring type over production.

    PTI   =   33.33   x    ( (WP)            x              (FCM)                      (WT)          x (PTAT) )

                                    ( ——————————         +          —————————  )

                                    (               SDFCM                                            SDPTAT              )

 

where   WP   =  weighing factor for Production

            WT   =  weighing factor for Type

                         (when WP = 2, WT must = 1)

                         (when WP = 1, WT must = 2)

            FCM  =  Fat Corrected Milk from step 1

            SDFCM =  Standard Deviation for FCM

                           (breed specific – see Table 1)

             PTAT = Predicted Transmitting Ability for Type available to  ADGA membership through the ADGA Performance Volumes or by calling the ADGA Office for information on specific animals

             SDPTAT = Standard Deviation for PTAT

                            (breed specific – see Table 1)

Step 3 

Calculate two Estimated Transmitting Abilities (ETAs) from the sire and dam PTIs for each weighing factor.

              PTI (sire) + PTI (dam)

 ETA   =   ————————-     –  QL ( a qualifying level determined each year by breed)

                        2

NOTE:   If a PTI cannot be calculated for the dam because of missing information, the alternate ETA below may be used.

                                                       (PTI (dam’s sire) )

                                 PTI (sire)  +    (——————-)

                                                       (          2            )

alternate ETA        =     —————————————-       –  QL

                                                          2

 PTI is from step 2, remember to pair the 2:1 PTIs for the 2:1 calculation and the 1:2 PTIs for the 1:2 calculation