Disease & heat resistance

Implementation of a national genetic evaluation for calf health traits in the U.S.

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Abstract

Calf health is critically important for long-term dairy sustainability and profitability. This study evaluated the feasibility of implementing a national genetic evaluation for calf health using data from the National Cooperator Database maintained by the U.S. Council on Dairy Cattle Breeding. Reporting of health events related to respiratory disease (RESP) and diarrhea or scours (DIAR) in calves has been available since the establishment of the health data format in 2008. Ongoing development of standardized procedures for identifying young female animals not retained in the herd aims to maximize data capture for calf health. Evaluations for Holstein and Jersey heifer calves were deemed feasible based on the currently available data, which now include approximately 765k RESP and 236k DIAR records. Incidence rates of DIAR and RESP in heifer calves were 12.6% and 15.2% in Holstein and 19.4% and 25.0% in Jersey, respectively. Variance components were estimated using a linear animal model similar to those currently used for cow health traits. Fixed effects included year-season of birth, parity of the dam, and regressions on inbreeding and heterosis, with random effects for animal, herd-sire interaction, and herd-year interaction. Heritability estimates were 2.6% for DIAR and 2.2% for RESP, considering both Holstein and Jersey. PTA correlations with existing traits were estimated using records from proven bulls. Significant correlations were observed between the two calf health traits, between calf health and heifer livability, and between RESP and cow longevity traits. Full genetic correlations will be estimated to evaluate the performance of a multi-trait model of calf health and heifer livability. Genomic evaluations were conducted using the standard set of 69k imputed SNPs used in routine US national evaluations. Mean genomic PTAs for animals born after 2020 averaged 0.08 ± 0.47 and -0.03 ± 0.34 for DIAR in Jerseys and Holsteins, and -0.01 ± 0.48 and -0.11 ± 0.51 for RESP in Jerseys and Holsteins, respectively. These PTAs are expressed as percentage points of resistance to the respective event relative to the population mean. Mean genomic reliabilities were 33% and 39% for DIAR and RESP in Jerseys, while mean genomic reliabilities in Holsteins were 45% and 59% for DIAR and RESP. Given these results, implementation of DIAR and RESP in the US national evaluation system is planned for 2026.

Keywords: 2026

How to Cite:

Neupane, M., Parker Gaddis, K., Tohgiani, S., Miles, A., Graham, J., Dürr, J., Cole, J., O’Connell, J., Van Tassell, C. & VanRaden, P., (2026) “Implementation of a national genetic evaluation for calf health traits in the U.S.”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2284556. doi: https://doi.org/10.31274/wcgalp.23590

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