Project Number: 1265-31000-085-15
Project Type: Specific C/A

Start Date: Sep 01, 2003
End Date: Aug 31, 2005

Objective:
Develop and evaluate a methodology to predict PTA of sires in different regions where regions are differentiated based on different levels of heat stress.

Approach:
The cooperator will use test-day production data kept by USDA for Holsteins. The cooperator will identify several weather stations per state and will obtain daily THI (temperature-humidity index) measurements for the past 10 years from these weather stations. The cooperator will streamline methodology to match each test day record with THI records from the closest weather station. Computer programs will be developed to analyze a test-day model using a large part of the U.S. dairy population with a random regression on a heat stress function. Breeding values will be calculated using the national data with both a lactation and test day model and the weather information. Separate breeding values will be calculated using regional data and ignoring the weather information. If regional differences are partly due to a heat stress, a regional evaluation should be similar to a national evaluation adjusted for heat stress typical for that region.

Project Team

Norman, H - Duane Ignacy Misztal - Professor, Animal And Dairy Science 301-504-8334

Related National Programs

Food Animal Production (101)