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Title: GENETIC EVALUATION OF STILLBIRTH IN UNITED STATES HOLSTEINS USING A SIRE-MATERNAL GRANDSIRE THRESHOLD MODEL

Author
item Cole, John
item Wiggans, George
item Vanraden, Paul

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2006
Publication Date: 5/1/2007
Citation: Cole, J.B., Wiggans, G.R., Van Raden, P.M. 2007. Genetic evaluation of stillbirth in United States Holsteins using a sire-maternal grandsire threshold model. Journal of Dairy Science. 90(5):2480-2488.

Interpretive Summary: A routine genetic evaluation for stillbirth has not previously been feasible due to insufficient data. However, 3.5 million stillbirth records were added to the national database in the last decade, suggesting that an evaluation may now be possible. Six million records from Holstein calvings were extracted from the database and used to calculate PTA for 44,290 AI bulls. Mean PTA were 7.9 and 8.6 for direct and maternal stillbirth, respectively. Reliabilities averaged 45%. There was no genetic trend for either trait. Improved recording of stillbirths would increase reliabilities and could allow for evaluations of breeds other than Holstein.

Technical Abstract: A sire-maternal grandsire threshold model was used for genetic evaluation of stillbirth in U.S. Holsteins. Calving ease and stillbirth records for herds reporting at least 10 dead calves were extracted from the AIPL database. About half of the 14 million calving ease records in the database have a known livability score, mostly from herds processed by Dairy Records Management Systems (Raleigh, NC). Calf livability scores of 2 and 3, representing calves born dead and calves that died within 48 h of parturition, respectively, were combined into a single category. The model included effects of herd-year, year-season, parity-sex, sire, birth year group of sire, maternal grandsire (MGS), and birth year group of MGS. Herd-year, sire, and MGS were random effects. Mean PTA, expressed as expected percentage of stillbirths, were 7.9 and 8.6 for direct and maternal stillbirth, respectively. Mean reliabilities for the direct and maternal effects both were 45%. Correlations among domestic and Interbull stillbirth solutions on the underlying scale for bulls with at least 90% reliability ranged from 0.63 to 0.90 across countries for direct SB, and 0.69 to 0.96 for maternal stillbirth, indicating that results were generally consistent with those from other countries. There was no evidence of a genetic trend for either trait. More complete recording of stillbirth scores would improve reliabilities and could allow for evaluations of other breeds.