Length of Estrous Cycle and Duration of Estrus following Natural and Induced Estrus in Korean Native Goats

山羊의 自然 및 誘起發情時 發情週期 및 發情持續時間에 관한 硏究

This study was carried out to investigate the length of the estrous cycle and duration of estrus in Korean native goats. The effects of the type of last estrus : induced or natural, and the length of preceeding estrous cycle on the subsequent cycle and duration of estrus in goats were also examined. From 481 observations, the mean length of estrous cycles was 18.1${\pm}$0.5days. The cycle length was significantly(P<0.05) shorter following induced estrus (15.2${\pm}$0.8 d) than natural estrus(19.0${\pm}$0.6 d). Significantly higher(P<0.05) incidence of short estrous cycle was observed following induced estrus(40%) than natural estrus(27%). The frequency distribution in the estrous cycle was 30%, 3%, 56% and 11% for short(3-11 d), medium(12-16 d), normal(17-24 d) and long(${\geqq}$25 d), respectively. The most frequent type of short estrous cycle was 6 days in length. Mean duration of estrus was 34.0${\pm}$0.5 h with a range of 18 to 84 h. Duration of estrus was not significantly different the preceeding natural (33.8${\pm}$0.6 h) and induced estrus (34.4${\pm}$1.1 h), and was not significantly affected by the last cycle length. These results suggest that the short estrus cycles are more frequent following induced estrus than natural one, and the duration of estrus are affected greatly by the various intrinsic and extrinsic factors.

在來山羊의 發情週期와 發情持續期間을 조사하고자 정관 절제 시술한 시정모 산양을 이용하여 90두의 암산양으로부터 3년간에 걸쳐 총 148회의 방정주기를 관찰하였다. 총 481회의 발정주기의 평균기간은 18.1${\pm}$0.5이었고, 11일 이하의 短發情週期가 143회(30%), 12일에서 16일의 中發情週期가 15회(3%), 17일에서 24일의 正常發情週期가 268회(56%) 및 25일 이상의 長發情週期가 55회(11%)로 나타났다. 短發情週期의 발생율은 자연발정후(27%)보다 유기발정후(15.2${\pm}$0.8)일에 유의적(P<0.01)으로 짧았다. 短發情週期에 있어서는 143회중 6일의 기간을 가지는 빈도가 92회로 가장 많았다. 발정지속 시간의 평균은 34.0${\pm}$0.5시간이었는데, 발정지속시간에 있어서는 자연발정과 유기발정간에 유의적인 차이가 없었다. 이상의 결과로 在來山羊의 發情週期는 自然發情後에 있어서 보다 誘起發情間에 차이가 없음을 알 수 있다.