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Title:   Author  item
                                            Vanraden, Paulitem
                                            Sanders, Ashleyitem
                                            Tooker, Melvinitem
                                            MILLER, ROBERT - RETIRED, ARSitem
                                            Norman, H
  Submitted to: AIPL Research Reports
                                    Publication Type: Government Publication
                                    Publication Acceptance Date: 12/10/2002
                                    Publication  Date: N/A
                                    Citation: N/AInterpretive 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.


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