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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: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings
Publication Acceptance Date: 5/6/2006
Publication Date: 8/13/2006
Citation: Cole, J.B., Wiggans, G.R., Van Raden, P.M. 2006. Genetic evaluation of stillbirth in United States Holsteins using a sire-maternal grandsire threshold model. 8th World Congress of Genetics Applied in Livestock Production. Communication 01-28.

Interpretive Summary: A sire-maternal grandsire (MGS) threshold model was used for genetic evaluation of stillbirth in US Holsteins. Data consisted of almost 7.5 million records, and over 41,000 AI bulls received evaluations. The model included effects of herd-year, year-season, parity-sex, sire, birth year group of sire, MGS, and birth year group of MGS, and dystocia score. Herd-year, sire, and MGS were random effects. Mean PTA, expressed as expected percentage of stillbirths in heifers, were 12.47 and 14.28 for direct and maternal stillbirth, respectively. Reliabilities for the direct and maternal effects averaged 0.53 and 0.52, respectively. Dystocia scores had a larger effect on stillbirth than year-season, sire, or MGS effects. Correlations among US 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 SB, indicating that results were generally consistent with those from other countries. There was no evidence of a consistent genetic trend. More complete recording of stillbirth scores would improve reliabilities and possibly allow for evaluations of other breeds.

Technical Abstract: A sire-maternal grandsire (MGS) threshold model was used for genetic evaluation of stillbirth in US Holsteins. Data consisted of almost 7.5 million records, and over 41,000 AI bulls received evaluations. The model included effects of herd-year, year-season, parity-sex, sire, birth year group of sire, MGS, and birth year group of MGS, and dystocia score. Herd-year, sire, and MGS were random effects. Mean PTA, expressed as expected percentage of stillbirths in heifers, were 12.47 and 14.28 for direct and maternal stillbirth, respectively. Reliabilities for the direct and maternal effects averaged 0.53 and 0.52, respectively. Dystocia scores had a larger effect on stillbirth than year-season, sire, or MGS effects. Correlations among US 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 SB, indicating that results were generally consistent with those from other countries. There was no evidence of a consistent genetic trend. More complete recording of stillbirth scores would improve reliabilities and possibly allow for evaluations of other breeds.