Genomic Evaluation for Clinical mastitis in Czech Holstein

ZAVADILOVÁ, Ludmila, KAŠNÁ, Eva, KUČERA, J. a BAUER, J., 2022 Genomic Evaluation for Clinical mastitis in Czech Holstein. In INTERBULL BULLETIN NO. 57.. Montreal, Canada: ICAR, s. 89-94. ISSN
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Genomic breeding values for resistance to clinical mastitis (CM) have been estimated using a single-trait or multi-trait model; the latter comprised besides CM also linear udder traits and somatic cell count (SCC) transformed to somatic cell score (SCS). Dataset included 79,431 Holstein cows and 132,614 lactations with a lactation incidence of clinical mastitis for all lactations 19.91%. Cows calved between 2017 and 2021 in 104 herds. CM was defined as binary trait with 0 (no case) and 1 (at least 1 case) during the lactation, SCC as the average value per lactation. The linear type traits were udder depth, udder width, suspensory ligament, and udder’s subjective score in %. The single-step genomic method was employed to predict CM genomic breeding values (GEBV_CM). Linear model equations included the random additive genetic effect of animal and for CM and SCS fixed effects parity and age at calving class, herd-year-season of calving and random effect of the permanent environmental effect of a cow; for linear udder traits herd-year-season of scoring, classifier and linear and quadratic regression on the age at calving and the days in milk. Pedigree involved 208,217 animals. Number of genotyped animals was 35,472; effective animals 35,131; bulls 5,377, cows 14,941 and heifers 15,154. The final number of effective SNPs was 35,338. Heritabilities were 0.22 udder assessment, 0.38 udder depth, 0.19 udder support, 0.16 udder width, 0.11 SCS, 0.04 CM; genetic correlations between CM and udder assessment -0,30, udder depth -0,41, udder support -0,30, udder width, 0.11 SCS. The mean of GEBV_CM was 0.0047 and 0.0174 for the multi-trait and single-trait models, respectively. An increase in the reliability of the breeding value appeared in the multi-trait model compared to the single-trait model. The average reliability of GEBV_CM increased for young genomic bulls (235, born 2019) from 0.22 to 0.45; for genomic heifers (15,154) from 0.27 to 0.50.

ProjektNavýšení spolehlivosti celostátního genomického hodnocení dojeného skotu zařazením krav s domácí užitkovostí do genotypované referenční populace, Dlouhodobý koncepční rozvoj výzkumné organizace
OdděleníGenetika a šlechtění hospodářských zvířat