遺伝・育種

[III-18-02] Genetic study for age at calving in Japanese Black cows

*Asep Setiaji^1,2,3, Takuro Oikawa^1,2 (1. Univ. of the Ryukyus, 2. The United Graduate Schools of Agricultural Sciences, Kagoshima Univ., 3. Diponegoro Univ. Indonesia)

The objective of this study was to estimate genetic correlation between age at calving and reproductive performances of Japanese Black cows. Age at calving comprises age at first calving (AFC), age at second calving (ASC) and age at third calving (ATC). Reproductive performances assessed were; non-return rate (NRR), number of inseminations (IN), days from first to successful insemination (FS), gestation length (GL), days from calving to first insemination (CF), days open (DO), pregnancy rate (PR) and calving interval (CI). Genetic parameters were estimated by residual maximum likelihood (REML). The estimated heritability of age at calving were 0.158, 0.107 and 0.088 for AFC, ASC and ATC, respectively. The lowest genetic correlation in absolute value was observed between ATC and GL (-0.086) and the highest between AFC and IN (0.661). AFC was demonstrated the highest heritability and moderate to high genetic correlations with CF, CI, PR, DO, FS and IN. Selection of AFC would provide higher genetic improvement in reproductive performance of Japanese Black cows.