Preliminary Results from a Genetic Analysis of Clinical Mastitis Data for Holstein cattle in Czech Republic
Keywords:mastitis, somatic cell score, genetic evaluation, genetic parameters, Holstein cattle
AbstractCases of mastitis from 22 812 lactations of 10 294 cows were recorded on 7 farms in the Czech Republic from 2000 to 2012. The number of clinical mastitis (CM) cases per lactation (CM1), the number of days of CM per lactation (CM2) and CM considered as an all-or-none trait (CM3) with values of 0 (no CM case) and 1 (at least 1 CM case) were analyzed with linear animal models. Bivariate linear animal models were used for estimation of genetic correlation between CM traits and lactation mean somatic cell score (SCS) or 305-d milk yield (MY305). Factors included in the model of choice were parity, effect of herd, year of calving period, calving season, permanent environmental effect of the cow, and additive genetic effect of the cow. Estimated heritability for CM traits were in the range (0.9 – 0.10). Permanent environmental effects accounted for approximately two-third of the phenotypic variance. Heritability estimates for lactation mean SCS(305) and 305-d milk yield were 0.23 and 0.24, respectively, and genetic correlations of SCS(305) and MY305 with of CM traits were 0.22±0.062, 0.23±0.064, 0.29±0.086, 0.80±0.037, 0.79±0.040 and 0.83±0.038, respectively. Spearman rank correlations between breeding values for different CM trait definitions and SCS(305) for 139 sires with reliability of breeding value over 50% in the analyzed dataset were in the range (0.53 – 0.77). Genetic evaluation of CM cases in Czech Holsteins could be carried out including data from all parities using linear animal model. Regarding the selection character CM, our analysis showed that can be used by any of the analyzed characters. The limiting factors will likely availability of data on mastitis.
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).