Select Sires

SELECTIONS - Winter 2002
PRODUCTIVE LIFE: Good Information, But Handle With Care

By Charlie Will, dairy sire analyst

USA included Productive Life (PL) information in the Type-Production Index (TPI™) formula almost two years ago, PL has become a buzzword.

Productive Life is an index the industry developed to help predict "stayability" of cows in a herd. And it certainly has done a good job sorting the wheat from the chaff for high-reliability bulls.

The PL formula was designed so that one Productive-Life point equals one month of a cow’s life. Using a real-world example, daughters of 7HO3707 Paradise-R Cleitus MATHIE*CV (PL +2.9, 99 percent Reliability) should stay in herds six months longer than daughters of a bull with a Productive Life score of -2.9 at 99 percent Reliability.

Because Productive Life is designed to measure longevity, the challenge is that it takes time to gain an accurate measure of what a bull transmits. To reliably predict how long a bull's daughters will last, we need many daughters with completed records.

COMPARING HERITABILITIES OF TRAITS
If in the third month of lactation a 2-year-old is milking 100 pounds per day, you quickly can predict that she will be a high-producing cow. But at this time, how accurately can you predict the length of time she will stay in the herd?

A cow does not begin to contribute any actual culling information to her sire's PL evaluation until after she reaches 3 years of age. Therefore, the Productive-Life scores you see on all new active-A.I. sires are calculated using pedigree information, somatic cell score, and the corrolated production and type traits the formula uses to predict longevity.

This translates into a heritability of only 8.5 percent for Productive Life. That compares with 30 percent for production traits.

FIRST-CROP BULLS HAVE LOW RELIABILITIES
When reviewing the November list of all active-A.I. Holstein sires ranked by TPI, among the top 100 sires there was only one that had a reliability of at least 70 percent for Productive Life. In fact, most active-A.I. sires average between only 40 and 60 percent reliability.

If a sire had reliabilities of only 40 to 60 percent for production traits, you probably would wait for more information before using him in your breeding program. Should your standards for PL be any different?

As a rule of thumb, if a sire has a 90 percent reliability for production with some completed daughter records, he should have about a 70 percent reliability for Productive Life. Most bulls have PL reliabilities lower than 70 percent until their second-crop daughters begin milking. The bottom line is that it takes a lot of daughters through time to earn a high reliability for PL. You conveniently can find PL reliability information for all Holsteins in Select’s lineup in our sire directory.

PRODUCTIVE LIFE AFFECTS TPI
Productive Life accounts for about 13 percent of the TPI calculation. In researching the practical impact of Productive Life, I found that a one-point improvement in PL score will add about 45 TPI points. So until a sire’s Productive Life reliability is high, his TPI ranking can change dramatically due only to PL score changes.

IS LONGER BETTER?
As a general rule, the longer a cow remains in the herd, the better. The key, however, is that a cow be more profitable - not just live longer.

To make the most genetic progress with each mating, focus first on traits that add to lifetime profitability: milk, fat and protein yield, better udders and feet and legs, and adequate strength. View sires that have highly reliable scores for Productive Life with confidence.

™TPI is a trademark of Holstein Association USA

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