부산대학교 도서관

This study was carried out to estimate the effects of environmental factors and genetic parameters on gestation length, calving interval and birth weight of Holsteins. The data used for this study was the reproduction records of Holsteins which were perfomtance- tested at the National Livestock Research Institute from 1969 to 1988. The effects of parity, lunar calendar day at A. I. time and calving year were not significant for gestation length, but calving season, sex of calf and sire were significant (P$lt;0.01) for gestation length. The parity, calving year and sire were significant(P$lt;0.01) for calving interval. There were significant effects on birth weight between parities (P$lt;0.01), calving seasons(P$lt;0.01), sex of calf(P$lt;0.01) and sires(P$lt;0.05). The least square means and standard errors for gestation length and calving interval ranged from 278.18±1.58 days to 279.59±1.40 days and from 358.60±19.03 days to 434.99±12.51 days through parities, respectively. Especially, the results showed that the calving interval was shorted with increasing parity. The birth weights ranged from 40.63±1.24㎏ to 44.87±3.47㎏ and from 40.58±0.79㎏ to 42.74±0.90㎏ through calving years and calving seasons, respectively. The estimated heritabilities of gestation length, calving interval and birth weight were 0.11±0.06, 0.07±0.09 and 0.09±0.05, respectively. The estimated genetic and phanotypic correlations between gestation length and calving interval were 0.40±0.06 and - 0.01±0.63, respectively.