A model for the genetic evaluation of number of clinical mastitis cases per lactation in Czech Holstein cows.
Cases of mastitis from 9,550 lactations of 6,242 cows were recorded on 5 farms in the Czech Republic from 1996 to 2008. The number of clinical mastitis (CM) cases per cow adjusted to a lactation length of 305 d was analyzed with 4 linear single-trait animal models and one 3-trait model, which also included lactation mean somatic cell score (SCS) and 305-d milk yield. Factors included in the model of choice were parity, combined effect of herd and a 2-yr calving period, calving season, permanent environmental effect of the cow, and additive genetic effect of the cow. From both the single-trait and multiple-trait models, estimated heritability of number of CM cases was 0.11 (+/-0.015 for the multiple-trait model). Permanent environmental effects accounted for approximately one-third of the phenotypic variance. Heritability estimates for lactation mean SCS and 305-d milk yield were 0.17+/-0.019 and 0.25+/-0.011, respectively, and genetic correlations of these traits with number of CM cases were 0.80+/-0.059 and 0.34+/-0.079, respectively. Genetic evaluation of the number of CM cases in Czech Holsteins could be carried out including data from all parities using a 3-trait animal model with SCS and milk yield as additional traits.
Wolf
J
J
Institute of Animal Science, Prague Uhríneves, Czech Republic. wolf.jochen@vuzv.cz
Wolfová
M
M
Stípková
M
M
D000818:Animals; D001947:Breeding; D002417:Cattle / Q000235:genetics*; D018153:Czech Republic; D005260:Female; D007774:Lactation; D008297:Male; D008414:Mastitis, Bovine / Q000235:genetics*; D008892:Milk / Q000166:cytology / Q000378:metabolism; D008957:Models, Genetic; D019655:Quantitative Trait, Heritable