Genetic parameters for female fertility in Nordic dairy cattle

Abstract

Nordic Cattle Genetic Evaluation (NCGE) is in the process of updating the fertility model. The fertility traits have low heritabilities; hence the accurate (co)variance components are important for the estimation of breeding values. Multitrait-multilactation sire model with 11 traits was used for analyzing i) non-return rate in 56 days (NRR), ii) interval from the first insemination to the last insemination (IFL), and iii) interval from calving to the first insemination (ICF). The data consisted of Swedish Holstein (N=144,392) and Nordic Red Dairy Cattle (RDC, N=103,653) heifers and cows with three first lactations. The heritabilities in different lactations in both the breeds ranged around 0.01 in NRR, and from 0.01 to 0.04 in IFL. In ICF the heritabilities were 0.06 - 0.07 in Holstein and 0.03 - 0.05 in RDC. The within-trait, across-lactation genetic correlations in cow traits were in general high, they spanned from 0.78 to 0.97 in Holstein and from 0.56 to 0.91 in RDC. Across the traits the correlations in cow traits varied more than within traits; the highest correlations occurred within the lactations. The heifer traits and cow traits correlated from 0.23 to 0.74 within the traits. Across the traits the heifer-cow correlations varied from low to moderate. The results were found logical and can be used as variance parameters for the fertility traits in the model to be updated.