1a. Objectives (from AD-416)
Determine traits that would benefit most from expanded educational efforts. Develop computer programs to illustrate how daughters of superior bulls nationally for the traits of interest deliver an advantage within an individual producer’s own herd. Promote the development of an efficient and healthy national dairy herd through demonstration of genetic selection results. Provide a convenient way of using the software developed for extension type meetings of dairy producers.
1b. Approach (from AD-416)
Records from the national dairy database will be shared with PSU cooperators. Existing AIPL programs will be modified to identify the top and bottom quartile of cows each year based on sire PTA + 1/2 MGS PTA. The performance of the top and bottom quartiles will be compared. The number of observations needed to reliably demonstrate that genetic selection results in superior performance will be determined. Web applications will be developed that will allow users to query the AIPL database for herd specific results, including performance charts for each trait with a link to the cows and sires in each group. Demonstrate the tool to producer groups.
3. Progress Report
The project is related to in-house objectives 2 (characterize phenotypic measures of dairy practices and provide the industry with information for determining impact of herd management decisions on profitability) and 3 (improve accuracy of prediction of economically important traits currently evaluated). Response to genetic selection in individual herds by Holstein and Jersey cows with first calvings from 2005 through 2008 were documented for yield (milk, fat, and protein), somatic cell score, productive life, and days open. Standard deviations of individual-herd coefficients for regression of the measured trait on genetic merit based on sum of parents' predicted transmitting abilities were large. However, response to genetic selection on a within-herd basis could be demonstrated. Increasing the number of records per herd did not improve predictive ability but did increase the uniformity of the observed response. The response was greater for higher production herds and also for herds with more complete identification. Illustration of individual-herd response to genetic selection should increase confidence in national genetic evaluations in well-managed herds. Material has been prepared and sent to appropriate producer organizations to obtain approval for the use of records in software development and future demonstration of software effectiveness. Monitoring activities for the project included discussions at the Cooperator's facility and at jointly attended activities as well as two conference calls, several phone calls between the principal investigators, and e-mail exchanges of results produced by the project. In addition, preliminary results were shared with stakeholders at a joint meeting of the Council on Dairy Cattle Breeding and the National Association of Animal Breeders in April 2010.