Holstein World: What do bulls that sire durable, long-lived genetics look like?

Marj & Dick: Many breeders relate easily to the conformation of daughters from high Type bulls, but few feel they can accurately describe linear traits for high longevity/durability bulls. In order to provide breeders with a “visual picture” of long-lived genetics, let’s compare a group of bulls with high Type (PTAT), our benchmark, and a subset of bulls that excel for Productive Life. Both groups of sires for this comparison were sorted from the U.S. Active A.I. list to ensure that there were sufficient numbers of bulls in the different subsets to reach robust conclusions.

The high Type subset was defined as bulls with PTAT of more than 1.4 and 189 active bulls met this criterion (August 2006 Active A.I. list). The high Productive Life subset was defined as bulls having a PL of 2.0 and higher, meaning that daughters of these bulls are expected to be productive and in the milking string for at least 2 months longer than bulls with PL values of 0 (174 active bulls). Details and graphics for this comparison are available in the ABS Dairy Breeders Journal, Fall/Winter 2006 issue which has been posted to the ABS Global web site for your convenience:
Under 2007, click on the link: “Breed Long Lasting Cows” http://www.absglobal.com/tech_serv/resources/dairy/geneticmanagement.phtml
Take-home points are provided in today’s blog:

High Type (PTAT > 1.4) subset of bulls (189 bulls) Excel for Udder Traits and Feet and Leg traits – as expected. Favorable associations with longevity (PL).
 Large cows which are extreme for Stature, Strength, Body Depth, Thurl Width, and Dairy Form/Angularity. Unfavorable associations with longevity, fertility, and durability.
 Elite for Type.
 Essentially average for Management Traits – Productive Life, Daughter Pregnancy Rate, Somatic Cell Score, Sire and Daughter Calving Ease and Stillbirths, and Lifetime Net Merit Dollars (NM$).

High Productive Life (PL ≥ 2.0) subset of bulls (174 bulls)
 Excel for Udders and Feet and Leg structure traits. Favorable associations with longevity (PL).
 More moderately sized cows which are less extreme for Stature, Strength, Body Depth, Thurl Width, and also less extreme for Dairy Form – a more modern frame. Cows which fit in today’s parlors and freestalls and further show that they have sufficient body reserves available for the immune system, reproduction, and maintaining a pregnancy.
 Good Type (average PTAT = 0.92). Functional type and a more modern frame.
 Elite for Productive Life, greater ability to avoid culling, improved ability to breed back, greater ability to avoid mastitis, more ability to calve easily with a live calf – overall average of $343 for Lifetime NM$.

This entry was posted on Friday, February 16th, 2007 at 9:31 am by sschmidt and is filed under Guest Blogger Series. Hits for this post:9 You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.