engleski

Estimation of genetic parameters for calving interval in Croatian Simmental breed

Selection for higher milk production leads to a decreased fertility performance due to genetic antagonism. Poor fertility is manifested as a low non-return-rate, prolonged lactation, and finally as involuntary culling of dairy cows. The objective of this study was to estimate genetic parameters for calving interval as a fertility parameter in Croatian Simmental breed. Data consisted of 103 046 records for completed standard 305-d lactations, taken from the central database of Croatian Agricultural Agency. The number of animals in pedigree was 82 188. Statistical model included the following fixed class effects: region, calving season and interaction between milk production level and parity. Age at first calving was modelled as quadratic regression. Herd, herd and calving year interaction, direct additive genetic and permanent environment effects were included as random. Variance components were estimated using REML method as implemented in the VCE-6 program. The estimated variances (ratios ± standard error) were: 381.4 (0.06±0.003) for herd, 190.6 (0.03±0.002) for herd and calving year interaction, 415.3 (0.06±0.006) for direct additive genetic and 438.6 (0.06±0.006) for permanent environment effect. Estimated genetic parameters will be used for genetic evaluation of calving interval in Croatian Simmental breed.

Simmental cattle; calving interval; genetic parameters

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