Evaluation of fetal growth and estimation of fetal age based on skeletal growth in Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884).
We investigated fetal development and the estimation of fetal age of 127 Hokkaido sika deer fetuses, categorizing them into three groups according to the nutritional condition of populations. The order and time of the appearance of ossification centers were clarified, and fetal age was determined based on bone length and the appearance of ossification centers. Then we observed the differences in fetal growth among three populations, and discussed the effect of poor nutrition on the fetal growth. The results suggest that fetal diaphysial length of the femur was affected very little by nutritional conditions, whereas conception dates were delayed and fetal weight was restricted as the nutritional condition became poorer. Although it is impossible to know the exact accurate fetal age in wild populations, it was possible to create a standard to estimate fetal age more precisely by the method described in this study. Both the bone length and the appearance of ossification centers are reliable indices to estimate fetal age precisely in measurements available from fetuses of unknown age, and can be applied to estimate the fetal age of other populations of sika deer, whereas estimation of fetal age based on weight is prone to great errors.
Kobayashi
Asuka
A
Laboratory of Wildlife Biology, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo 060-0818, Japan.
Onuma
Manabu
M
Yokoyama
Mayumi
M
Suzuki
Masatsugu
M
Uno
Hiroyuki
H
Ohtaishi
Noriyuki
N
D000365:Age Determination by Skeleton; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001837:Body Weights and Measures; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000196:embryology*; D003670:Deer / Q000196:embryology*; D005333:Fetus / Q000000981:diagnostic imaging / Q000196:embryology*; D005865:Gestational Age; D007564:Japan; D012015:Reference Standards