Select Sires

SELECTIONS - Winter 2006
Selecting for Healthier Transition Cows

by Chuck Sattler, vice president, genetic programs

Metabolic Stress

Everyone appreciates profitable, trouble-free cows. There is no question that the modern dairy cow is capable of high production. In today’s production settings, it’s increasingly common to find high-producing cows that do it rather easily and others that start out great but when challenged seem to give up and don’t achieve their potential without special treatment or intervention.

Cows face tremendous challenges during the transition period from calving to peak lactation production. Nearly all cows go through a period where they are not eating enough to meet their energy needs and begin mobilizing body tissue reserves to maintain themselves and continue producing milk. This is a very stressful period for cows.

There is variation in how cows respond to this metabolic stress.

Some cows respond by eating more and are able to sustain amazing feed conversion rates to get them through this demanding period.

Other cows have strict regulatory mechanisms that assure they partition some energy toward maintenance and reproduction so they continue to be functional during these high production months.

And then there are those that seem to have lost that regulatory control and continue to strive to produce milk regardless of their body condition. These cows are the ones that get into trouble.

Our breeding programs need to produce cows that can milk at high levels but don’t suffer from an extreme amount of metabolic stress.

Traditionally we’ve been taught that this was accounted for in our production PTAs as cows that are persistent and go on to make outstanding second and third lactations eventually have better production PTAs.

But experience is showing that selection tools in addition to PTAs for production are needed to adequately address these issues.

Dairy Form

Fortunately we’ve been measuring a trait all along that provides a good indicator of metabolic stress.

In the late 1990s, research from several different institutions and countries indicated an association between how much body condition a cow carries through lactation and her susceptibility to metabolic and reproductive diseases and foot and leg problems.

Research by Drs. Dechow and Rogers at Penn State University and the University of Tennessee documented that the linear type trait dairy form was closely correlated to body condition score and an even better indicator of disease frequency and productive life. They showed that cows with lower scores for dairy form tended to have fewer health problems and longer productive lives.

Using these results, in February 2003, Select Sires introduced the Herdlife Builder™ designation as an indicator of our lineup bulls that have a superior combination of type traits that contribute to improved productive life.

The Herdlife Builder designation is assigned to bulls that transmit superior udders and feet and legs and their daughters do not have extremely high dairy form.

The Holstein Association also has incorporated dairy form into their TPI™ formula. So, selecting for cows with lower dairy form scores has become a widely used tool to help us breed cows that can produce at high levels without suffering from an extreme amount of metabolic stress.

DuraMAX™

Functional genomics can play an especially helpful role in improving traits that are difficult to measure like metabolic stress.

Merial, through IGENITY™ Testing Services, has aggressively pursued researching genetic markers related to dairy cow metabolism.

These genetic markers could be very useful in breaking down the genetic antagonism between increased production and maintaining healthy cows.

The first result of Select Sires’ collaboration with Merial is the release of a new genetic test called DuraMAX. The DuraMAX test looks directly at patterns in an animal’s DNA and indicates a genetic tendency to transmit low or high dairy form scores.

DuraMAX Genotype Chart

Research conducted by Select Sires and Merial on the last several years of proven PGA™ sires confirmed a strong association between a bull’s DuraMAX score and his eventual STA for dairy form.

This association between DuraMAX and dairy form carried through, as expected, to also be related to Productive Life (PL) and Daughter Pregnancy Rate (DPR) but to a lesser degree. (See chart.)

This new DuraMAX test can be used along with other IGENITY tests and our traditional genetic evaluations to help Select Sires identify young bulls and help you identify heifers that have greater potential for balancing high production with a low level of metabolic stress.

Genetic tools exist that can help us breed for cows that sustain high levels of milk production and do it easily.

Select Sires has recognized this and has been a leader in incorporating these tools in our bulls through programs like Herdlife Builder and the DuraMAX genetic test.

You can be assured that Select Sires is working hard to deliver genetics that produce profitable, trouble-free cows for your herd.

™TPI is a trademark of Holstein Association USA
™IGENITY and DuraMAX are trademarks of Merial, Duluth, GA
™Program for Genetic Advancement, PGA and Herdlife Builder are trademarks of Select Sires Inc.

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Select Sires Inc., 11740 U.S. 42 North, Plain City, Ohio 43064 / Phone: (614) 873-4683 Fax: (614) 873-5751