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Implementation of national health trait evaluations in Jersey.

K. L. Parker Gaddis

Abstract:

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Implementation of national health trait evaluations in Jersey.
K. L. Parker Gaddis*1, L. M. Jensen2, P. M. VanRaden3, J. H. Megonigal Jr.1, E. L. Nicolazzi1, H. D. Norman1, C. W. Wolfe4. 1Council on Dairy Cattle Breeding Bowie, MD, 2University of Florida Gainesville, FL, 3Animal Genomics and Improvement Laboratory, Agricultural Research Service, USDA Beltsville, MD, 4American Jersey Cattle Association Reynoldsburg, OH.

Health evaluations for 6 traits (resistance to milk fever, displaced abomasum, ketosis, mastitis, metritis, retained placenta) have been available for Holstein animals from the Council on Dairy Cattle Breeding (CDCB; Bowie, MD) since April 2018. Recent research indicated that expanding these evaluations to include Jersey animals was feasible. Concurrently, there was a 112% increase in the total number of usable Jersey health records submitted to CDCB in the span of one year beginning in January 2019. Total number of available phenotypic records by trait as of January 2020 ranged from 85,417 for ketosis to 168,342 for mastitis. Overall incidence ranged from 1.2% for milk fever up to 10.4% for mastitis, similar to those found in Holstein. Heritabilities were assumed to be equivalent to those in Holstein, ranging from 0.6 to 3.1%. The same pipelines as those currently used for CDCB Holstein health evaluations were expanded to include Jersey data. Phenotypes are pre-adjusted for unequal variance before evaluation. Traditional PTA are estimated using a univariate BLUP repeatability animal model accounting for year-season, age-parity, herd-year, and permanent environmental effects, as well as a regression on inbreeding and heterosis. Genomic PTA are calculated with 79,294 markers used in CDCB routine genomic evaluations. Resulting PTA are presented as percentage points above or below the breed's average resistance with more positive values being favorable. Average traditional reliabilities for bulls born since 1990 with ≥90% net merit (NM$) reliability ranged from 17 to 32%, depending on trait. Average genomic reliabilities for those bulls ranged from 29 to 49%, gaining 12 to 17 percentage points from the inclusion of genomic data. Maximum PTA reliability was 98% for mastitis. Correlations between health PTA and PTA of other routinely evaluated traits were calculated. Significant (P < 0.05) correlations ranged from −0.52 between mastitis and milk up to 0.33 between displaced abomasum and livability. Beginning with the April 2020 CDCB evaluations, Jersey animals will receive evaluations for all 6 health traits. The 6 health traits in NM$ will receive 2% emphasis.

Keywords: health, Jersey, national evaluation.