The effect of human chorionic gonadotropin on the reproduction performance in Lory sheep synchronized with different doses of pregnant mare serum gonadotrophin outside the breeding season.

摘要

Two experiments performed to determine the effects of different doses of PMSG and subsequent hCG treatment on the reproductive performance in estrus-induced mature Lory ewes. In first experiment 192 Lory anestrous ewes were divided into two groups and after synchronization with progestagen sponge (Fluorogestone acetate, 40 mg FGA) the ewes in first group (T₁) were injected 400IU PMSG and in second group (T₂) were injected 600 IU PMSG intramuscularly at sponge removal time. At insemination time (AI) time, ewes divided into 4 subgroups; T₁ and T₂h were injected 200 IU hCG and T₁C and T₂C were kept as the controls. In second experiment the effect of supplementing hCG at AI time or 12 days after AI were measured on the reproductive performance using 374 estrus-induced mature Lory ewes. After synchronization with progestagen sponge, all ewes were injected 400IU PMSG. The ewes then, were randomly divided into three groups: the ewes in (h₀) were injected 200 IU hCG at AI time, (h₁₂) were injected 200 IU hCG at day 12 after mating time and (C) were kept as the control group. Serums progesterone P4 concentrations were measured in days 12, 14 and 16 after AI in both experiments. The result of 1st experiment indicated that single lambs in T₁h subgroup had higher weight compared with T₁C subgroup at birth day (p<0.05). The prolificacy were higher in hCG treated groups compared with control (p<0.05). However, fertility did not differ significantly among subgroups. Mean weight of single lambs born was increased in T₁h compared with T₁C and T₁h subgroup had higher P4 concentration compared with T₁C subgroup (p<0.05). In Experiment 2; in comparison with control, the hCG increased prolificacy in h0 treatment (p<0.05). Mean weight of lambs born was significantly increased in h₀ and h₁₂ groups compared with control. The hCG increased P4 concentration in h₀ and h₁₂ group and the h₁₂ had higher P4 concentration compare with other groups (p<0.05). It can be concluded that hCG injection at AI time increased progesterone concentrations and subsequent could improve reproductive performance in Lory ewes but there were no differences between the ewes treated with 400 or 600 IU PMSG.