FERTILIZING COMPETENCE OF MULTIPLE OVULATED EGGS IN THE DOMESTIC-FOWL (GALLUS-DOMESTICUS)

Fertilizing competency of multiple ovulated eggs in the domestic fowl was examined by fertilization in vitro and early development in culture. Normal laying hens (White Leghorn) were treated with 75 IU of PMSG for 7 days followed by injection of anterior pituitary extracts from chickens (CAPE). Ovulation began to occur 7.5 h after injection of CAPE. These hens ovulated 1-7 ova but some premature ovulation of GV stage ova were observed. In vitro fertilization of the multiple ovulated ova was examined by inseminating 10(6)-10(7) sperm onto the germinal disks in m-Ringer's solution. The gamete or zygote nuclei were detected by DNA specific fluorescence using DAPI (4',6' -diamidino-2-phenylindole) in the histological section prepared from the germinal disk. Process of fertilization was examined in the eggs incubated for 4 h after insemination in DMEM + liquid albumen at 41-degrees-C under the atmosphere of 5% CO2 in air. Fertilization rate of the total multiple ovulated eggs was 55% (11/20), in which 90% (9/10) and 10% (1/10) in the eggs recovered 7.5-8.5 h and 9.0-9.5 h after CAPE injection were obtained, respectively. Normal pronuclei were formed in five eggs of those recovered 7.5-8.5 h after CAPE injection. Early development after fertilization in vitro was also examined by incubation for 12 h in DMEM + liquid albumen at 41-degrees-C under the atomosphere of 5% CO2 in air. Although development in vitro was delayed compared to that in utero condition, normal development was observed in naturally and multiple ovulated eggs. The developmental rate of the multiple ovulated eggs was 67% (20/30) in total, in which 94% (15/16) and 5% (5/14) were obtained in the eggs recovered 7.5-8.5 h and 9.0-9.5 h after CAPE injection, respectively. Both fertilization and developmental rate of the eggs recovered 9.0-9.5 h after CAPE injection were significantly lower (P < 0.01) than those recovered 7.5-8.5 h after CAPE injection or naturally ovulated. These results suggested that multiple ovulated fowl eggs recovered 7.5-8.5 h after CAPE injection had normal fertilizing and developmental ability in vitro.