GESTATION PERIODS IN THE PERE DAVIDS DEER (ELAPHURUS-DAVIDIANUS) - EVIDENCE FOR EMBRYONIC DIAPAUSE OR DELAYED DEVELOPMENT

It has been suggested that the gestation length of the Pere David's de er is around 280 days, which is significantly longer than any other de er species except the roe deer (approximately 300 days) which exhibits embryonic diapause. The present study was designed to determine wheth er embryonic diapause exists in the Pt?re David's deer by accurately m onitoring gestation length. There was no difference in gestation lengt h (283-284 days) between animals mated early and later in the breeding season. Hence, although Pere David's deer exhibit a longer gestation period than that predicted from maternal body weight, there is no evid ence for seasonal control of implantation. Actual birth weight is as p redicted from an interspecific comparison of ungulates. The data imply either that there is an obligate period of embryonic diapause, irresp ective of season, or that postimplantation fetal growth rate is slow c ompared with that in other deer species.