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ARS Home » Research » Publications at this Location » Publication #142354
Title: DAUGHTER PREGNANCY RATE EVALUATION OF COW FERTILITY

Author
item Vanraden, Paul
item Sanders, Ashley
item Tooker, Melvin
item MILLER, ROBERT - RETIRED, ARS
item Norman, H

Submitted to: AIPL Research Reports
Publication Type: Government Publication
Publication Acceptance Date: 12/10/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Animal Improvement Programs Laboratory (AIPL) will provide genetic evaluations for daughter pregnancy rate (DPR) beginning February 2003. Many producers have expressed concerns about the difficulty of achieving desired levels of reproductive performance in today's milking herds. Over the last year, AIPL staff examined several reproductive traits to determine if genetic selection for daughter fertility is possible and compared methods to evaluate and present this information. Calving interval and days open have been available from Dairy Herd Improvement Association (DHIA) data for many years, but were not evaluated routinely because fertility traits tend to have very low heritabilities (about .04). Predicted transmitting abilities (PTA) for cow fertility traits will have high reliabilities only after hundreds of daughters are recorded. For bulls with only first-crop daughters, reliabilities average about 60%, and parent averages still provide much of the information. Pregnancy rate and days open are almost the same trait genetically, and a 1% higher pregnancy rate equals 4 fewer days open. PTA DPR is not yet included in net merit, cheese merit, or fluid merit calculations, but will be added in future revisions of these indexes.

Technical Abstract: The Animal Improvement Programs Laboratory (AIPL) will provide genetic evaluations for daughter pregnancy rate (DPR) beginning February 2003. Many producers have expressed concerns about the difficulty of achieving desired levels of reproductive performance in today's milking herds. Over the last year, AIPL staff examined several reproductive traits to determine if genetic selection for daughter fertility is possible and compared methods to evaluate and present this information. Calving interval and days open have been available from Dairy Herd Improvement Association (DHIA) data for many years, but were not evaluated routinely because fertility traits tend to have very low heritabilities (about .04). Predicted transmitting abilities (PTA) for cow fertility traits will have high reliabilities only after hundreds of daughters are recorded. For bulls with only first-crop daughters, reliabilities average about 60%, and parent averages still provide much of the information. Pregnancy rate and days open are almost the same trait genetically, and a 1% higher pregnancy rate equals 4 fewer days open. PTA DPR is not yet included in net merit, cheese merit, or fluid merit calculations, but will be added in future revisions of these indexes.