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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Genomics and Improvement Laboratory » Research » Publications at this Location » Publication #408689
Research Project: Increasing Accuracy of Genomic Prediction, Developing Algorithms, Selecting Markers, and Evaluating New Traits to Improve Dairy Cattle

Location: Animal Genomics and Improvement Laboratory

Title: International evaluations for clinical mastitis in Brown Swiss

Author
item MOTA, RODRIGO - Council On Dairy Cattle Breeding
item PARKER GADDIS, KRISTEN - Council On Dairy Cattle Breeding
item Vanraden, Paul
item MCWHORTER, TAYLOR - Council On Dairy Cattle Breeding
item NICOLAZZI, EZEQUIEL - Council On Dairy Cattle Breeding

Submitted to: Interbull Annual Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/18/2023
Publication Date: 12/13/2023
Citation: Mota, R.R., Parker Gaddis, K.L., Van Raden, P.M., Mcwhorter, T.M., Nicolazzi, E. 2023. International evaluations for clinical mastitis in Brown Swiss. Interbull Bulletin. 59:182-186.

Interpretive Summary:

Technical Abstract: The SNP training for clinical mastitis (STCM) trait was introduced by the Interbull Centre in April 2021. Previously, the mastitis trait within the udder trait group allowed for a wide range of trait definitions: direct clinical mastitis, somatic cell score, or a combination of clinical/subclinical mastitis. Since the introduction of STCM, the Council on Dairy Cattle Breeding (CDCB) has participated with data for Holsteins and Jerseys, aiming to enhance the domestic SNP reference population with foreign evaluations. As expected, for Holsteins and Jerseys the inclusion of Multiple Across Country Evaluation (MACE) evaluations had a minor impact on the US evaluation due to the dominance of US animals in the reference population. In the August 2022 evaluation, Brown Swiss (BSW) animals began receiving domestic health evaluations in the US, which were also incorporated into the Net Merit Index. During the January 2023 test run, the Brown Swiss STCM successfully completed Trend Methods I and III validation at Interbull. Starting from the April 2023 evaluation, BSW foreign evaluations were included in the United States of America (US) clinical mastitis evaluations. The initial expectation was that the impact of this inclusion would be limited, as only two other foreign countries (France and Switzerland) contribute to the CDCB clinical mastitis evaluation. However, the observed impact on the evaluations was noticeable. Correlations between the current, April 2023, and the previous, December 2022, triannual genomic evaluations were as low as 0.73 for reference animals and 0.56 for young animals. Along with the significant variation in Genomic Estimated Breeding Values (GEBV), the mean genomic reliabilities (GREL) for young animals increased from 24% in December to 30% in April. These results can be explained by two main factors: i) the contribution of foreign bulls from France and Switzerland in the SNP reference population for US Brown Swiss made the inclusion of MACE evaluations more relevant; ii) a large number of US Brown Swiss clinical mastitis records became available prior to the April 2023 evaluation and were added to the national cooperator database. Large changes in GEBV and GREL resulting from the initial inclusion of foreign data are not expected in subsequent evaluations unless more countries participate.