Abstract

The objective of the present study was to evaluate estrus and conception rates obtained with the use of progesterone (P₄) cream in intravaginal sponges in conjunction with equine chorionic gonadotropin (eCG) or eCG plus royal jelly (RJ) given at the time of sponge withdrawal. A total of 365 fat tailed ewes were assigned randomly to two treatment groups: insertion of intravaginal sponge containing 30 mg (LNP; n = 188) or 60 mg (HNP; n = 177) progesterone for 12 days. For each treatment, 300 or 600 IU of eCG were compared with 100 or 300 IU of eCG plus 500 mg of RJ to assess the effect on reproductive parameters of ewes inseminated laparoscopically in the anoestrus season. Ewes in each group were inseminated with fresh diluted semen (10 × 10⁷ sperm per insemination dose). Inseminations were carried out 11 to 18 h after the first detection of estrus. Pregnancy diagnosis was done at approximately 55 days after insemination. For the 30 and 60 mg natural progesterone treated groups, estrous (22.3 versus 30.5%) and conception rates (50.0% for both treatments) did not differ significantly. Ewes that received 300 IU eCG plus 500 mg RJ had higher (P>0.05) conception rates (66.7 versus 47.6 and 40.0%) than those treated with only eCG (300 or 600 IU) at sponge removal. There was a significant (P≤0.05) delay in onset of estrus in ewes treated with 100 IU eCG plus 500 mg RJ when compared with the other treatment groups.

Key words: Royal jelly, equine chorionic gonadotropin (eCG), natural progesterone, artificial insemination, ewe.

Abbreviation

eCG, Equine chorionic gonadotropin; RJ, royal jelly; P₄,progesterone.