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Calf diarrhea (DIAR) and respiratory illnesses (RESP) are leading causes of calf mortality. This study aimed to develop a comprehensive US national genomic evaluation for these important calf health traits using producer-recorded data from the National Cooperator Database. Analyses included 207,602 calf records for DIAR (age 3 to 60 d) and 681,741 records for RESP (age 3 to 365 d) from all breeds (97.5% data from Holstein and Jersey calves) born between 2013 and 2024. Both traits were modeled as binary variables (0 = diseased, 100 = healthy) with breeding values expressed as disease resistance in percentage points. Overall incidence was 14.46% for DIAR and 16.05% for RESP, with Jerseys showing higher incidence than Holsteins. Heritability estimates from the all-breed model were 0.026 (DIAR) and 0.022 (RESP). Genomic PTA reliabilities exceeded pedigree PTA reliabilities, with young sires (born ≥2020) exhibiting high reliability for genetic improvement opportunities in calf health. Holsteins exhibited higher genomic reliabilities for both traits compared with Jerseys, likely due to the larger dataset. A moderate genetic correlation (0.22) was observed between DIAR and RESP, and correlations with heifer livability, another currently evaluated calf health trait, were 0.13 (DIAR) and 0.35 (RESP). Correlations of these health traits with other traits were low. These findings demonstrate the feasibility of including DIAR and RESP in the US national genetic evaluation system, enabling more effective breeding strategies to improve calf health and survivability.
Neupane et al. (Tue,) studied this question.