There have been some ongoing discussions on this site about how EPDs work. I spent some time this morning and found some sites that might be of interest to people.
http://ag.arizona.edu/pubs/animal/az9611.pdf
http://beef-mag.com/mag/beef_abcs_epds/
http://www.beefquality.biz/020812.htm - here are some quotes from this site:
"EPDs come from performance records — birth weights, yearling weights — and also from carcass measures of an individual. Complex calculations weigh that information, together with information about that individual's relatives, to come up with a value using a "mixed model" methodology. In the process, the information is adjusted to account for—and remove—effects of environmental differences in the real world. For instance, calves aren't all weaned at 205 days, nor in the same environment. The model adds or subtracts to level the playing field. "
"When it comes to the value of the EPD itself, the number is of less importance than the relative differences between animals, because the whole purpose of EPDs is comparison. It's not an absolute measure of performance."
http://www.ext.vt.edu/pubs/beef/400-804/400-804.html
And, BTW, I discovered that some sheep have EPDs. I didn't know that:
http://www.nsip.org/files/fs006.01.howtouseepds.pdf
http://ag.arizona.edu/pubs/animal/az9611.pdf
http://beef-mag.com/mag/beef_abcs_epds/
http://www.beefquality.biz/020812.htm - here are some quotes from this site:
"EPDs come from performance records — birth weights, yearling weights — and also from carcass measures of an individual. Complex calculations weigh that information, together with information about that individual's relatives, to come up with a value using a "mixed model" methodology. In the process, the information is adjusted to account for—and remove—effects of environmental differences in the real world. For instance, calves aren't all weaned at 205 days, nor in the same environment. The model adds or subtracts to level the playing field. "
"When it comes to the value of the EPD itself, the number is of less importance than the relative differences between animals, because the whole purpose of EPDs is comparison. It's not an absolute measure of performance."
http://www.ext.vt.edu/pubs/beef/400-804/400-804.html
And, BTW, I discovered that some sheep have EPDs. I didn't know that:
http://www.nsip.org/files/fs006.01.howtouseepds.pdf
