Estimation of heritability and genetic trend for herd life and productive life in Organic Holstein Cattle.

This study aims to estimate the heritability and genetic trend for herd life (HL) and productive life (PL) on an organic dairy cattle farm in the Aegean Region of Turkey. The data from 1093 cows culled from the farm were evaluated. Ancestors were collected by going 6 generations back. Thus, the pedigree file consisted of 4212 animals. Variance components and breeding values were estimated using the MTDFREML package program. The heritability for both HL and PL was found to be equal and 0.16. Standard errors of the heritabilities were 0.06 and 0.08, respectively. Genetic progress per year for HL and PL was 1.60 and 0.60 days, respectively. Estimations for HL and PL were generally consistent with other studies. Heritabilities indicate that breeding for HL and PL is possible; however, response to selection would be slow. Despite the extended length of the selection process, genetic variation could be sufficient for a successful breeding. Indirect selection based on particular traits that have a strong relationship with HL and PL may be beneficial. Our study showed a phenotypic decline in HL and PL, confirming the fluctuation in genetic trends. Therefore, the importance of life traits in the selection index should be emphasised.