Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Dairy calf health is a critical factor in the sustainability and profitability of dairy farming. Calf diarrhea (DIAR) and respiratory illnesses (RESP) are leading causes of calf mortality. This study aimed to develop a comprehensive U.S. national genetic evaluation for these important calf health traits using producer-recorded data from the National Cooperator Database. Analyses included 207,602 calf records for DIAR (3 to 60 d of age) and 681,741 records for RESP (3 to 365 d of age) from all breeds (~97% data from Holstein and Jersey calves) born between 2013 and 2024. Both traits were modeled as binary variables (0 = diseased, 100 = healthy). The overall incidence rates were 14.46% for DIAR and 16.05% for RESP, with Jerseys having a higher incidence than Holsteins. The median incidence age was 10 d for DIAR and 68 d for RESP. Heritability estimates from the all-breed model were 0.025 for DIAR and 0.021 for RESP. Reliabilities of genomic predicted transmitting abilities (PTA) were higher than those of traditional PTA, and young sires (born after 2020) had high reliability estimates, highlighting opportunities for genetic improvement in calf health. Holsteins exhibited higher genomic reliabilities for both traits compared to Jerseys, likely due to the larger number of genotyped and phenotyped animals. A moderate genetic correlation (0.22) was observed between DIAR and RESP, while correlations with heifer livability, another calf health trait currently evaluated, were 0.13 for DIAR and 0.35 for 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, offering a valuable tool for breeders to enhance calf health and survivability through genomic selection.