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This study evaluated the risk of using genomically-tested, young Holstein sires (GYS) to produce progeny with a low Nippon Total Profit index (NTP). The risk was defined as the probability that the progeny had a true NTP lower than the dam's estimated NTP. The service sires available as of August 2023 in Japan were divided into three classes : daughter-proven sires with 60 or more daughters with milk records (BULL-OLD), daughter-proven sires with fewer than 60 recorded daughters (BULL-NEW), and GYS with no daughters (BULL-GYS). Two classes of dams were considered : cows born in 2020 (COW-2020) and genomically-tested heifers born in 2022 (HEI-2022). For each class, we assumed a hypothetical animal with the average published NTP. We then used these animals as parents for mating. The true NTP of progeny was assumed to follow a normal distribution, with the mean as the parent average of estimated NTP and the variance as the sum of the prediction error variance of the parent average of estimated NTP and the Mendelian sampling variance. For COW-2020 (or HEI-2022), the risk for BULL-OLD was 14.4% (23.2%), for BULL-NEW, 10.2% (17.1%), and for BULL-GYS, 2.1% (4.1%). The result suggests that the genomically-tested young sires are more effective than daughter-proven sires in improving the average of the true NTP in dairy herds. [ABSTRACT FROM AUTHOR]

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Copyright of Nihon Chikusan Gakkaiho is the property of Japanese Society of Animal Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)