|COLE, JOHN - Former ARS Employee|
|Van Tassell, Curtis - Curt|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2021
Publication Date: 6/28/2021
Citation: Neupane, M., Hutchison, J.L., Cole, J.B., Van Tassell, C.P., Van Raden, P.M. 2021. Genetic and genomic evaluation of late term abortion recorded through Dairy Herd Improvement test plans [abstract]. Journal of Dairy Science. 104(Suppl 1):77(abstr. 196).
Technical Abstract: Late-term abortions cause significant economic loss and are of great concern for dairy herds. Late-term abortions >=152 days and <251 days of gestation that terminate a lactation or initiate a new lactation have long been recorded in Dairy Herd Improvement (DHI). For 22.7 million DHI lactations, the average recorded incidence of late-term abortions across all years was 1.2%. However, the 1.3% incidence of abortions reported in 2012 has declined to <1.0% incidence since 2015. Small adjustments were applied among the 82 million daughter pregnancy rate (DPR), 29 million cow conception rate (CCR), and 9 million heifer conception rate (HCR) records to more accurately account for late-term abortions. Fertility credits for CCR and HCR were changed to treat the last breeding as a failure instead of success if the next calving is coded as a late-term abortion. Similarly, when computing DPR, days open is now set to the maximum value of 250 instead of the reported days open if the next reported calving is an abortion. The test of these changes showed very small changes in SD and high correlations (0.997) of adjusted predicted transmitting abilities (PTA) with official PTA from about 20,000 HO bulls born since 2000 with >50% reliability. For late-term fetal survival as a trait, estimated heritability was only 0.001 and PTA had a SD of only 0.1% for recent sires with high reliability (>75%). Young animal genomic PTA have near 50% reliability but range only from -.5 to +.4 because of the low incidence and heritability. Bulls with highest genomic PTAs for fetal survival also had high productive life (PL) and fertility. Genetic trend was slightly favorable and late-term fetal survival PTA were correlated favorably by 0.08 with net merit, 0.38 with PL, 0.32 with livability, -0.23 with daughter stillbirth, -0.25 with daughter calving ease, 0.18 with CCR, 0.12 with DPR, and -0.15 with gestation length. Thus, PTA for late-term abortions should not be needed as a separate fertility trait and instead these minor edit changes should suffice. PTA for earlier abortions would add little value because national evaluations for current fertility traits already accounted for those economic losses.