چکیده (انگلیسی):

Objective: This study was conducted in order to the administration of 50 and 100 mg of
bovine somatotropin (bST) at the beginning of the estrus synchronization and natural
mating of the sheep to evaluate the improvement of the ovulation rate, embryonic
development and pregnancy rate of the transferred embryos.
Methods: Forty eight donors were treated with three different types of treatment; Group
A: treated with bST-100 (n = 15), received 100 mg of bST at the beginning of the
synchronization and natural mating, Group B: treated with 50 mg of bST (n = 15) same as
the previous group and control (n = 18) did not receive any type of bST. Each recipient
received two embryos, (n = 108): 30 recipients received the embryos from bST-100s, 45
recipients received the embryos from bST-50 and 33 recipients received embryos from
the control group. Using SAS related GENMOD method, rate of superovulatory,
recovered structure percentage, cleavage rate, transferable embryo percentage, quality of
embryos, rates of pregnancy and embryonic development were analyzed. Using GLM
procedure, numbers of corpus luteum and blastocyst cells were analyzed.
Results: The bST administration had no significant effect on rate of superovulatory,
number of CL and recovered structures (P
0.05). Number of transferable embryos and
embryos that had access to the blastocyst in bST-50 (P  0.01) was more than bST-100
and control group.
Conclusions: The treatment 50 mg bovine somatotropins enhance the ratio and growth
of the transferable embryos. Embryos of bST-50 treatment indicated an improved embryonic
development but bST did not affect the pregnancy rates of transferred embryos.