Effects of types of vaginal sponge impregnated with progestogen on estrus induction and lambing rate in seasonally anestrous ewes

For out-of-seasonal breeding, types of vaginal sponges and progestogens were compared in two field trials. The materials used were as follows; I) 60 mg medroxy-progesterone acetate (MAP)-impregnated sponge (supplied by the Upjohn International, Australia), II) 500 mg progesterone-impregnated empty-MAP sponge, and III) 500 mg progesterone-impregnated self-made sponge. The sponge was inserted in the vagina for 12 (Trial 1) and 9 days (Trial 2). A 600 IU PMSG was injected intramuscularly in ewes at the time of sponge removal, and a synthetic LH-RH (Conceral, 100 μg) was also given in ewes at the time of estrus detection. In trial 1, the proportion of estrous ewes within 5 days after treatment was satisfactory (94-100%) with no significant differ-ences among the groups. The mean time of induced estrus was significantly (P<0.05) earlier in the ewes treated with 500 mg progesterone-impregnated sponges than that with MAP sponges. The lambing rates were 85, 60 and 57% for groups I, II and III, respectively. However, they were not significantly different. In trial 2, the proportion of estrous ewes was generally low (68-88%) with no significant differences among the treatments. The lambing rates of the ewes mated following the sponge removal were also low (31-33%). However, there were no significant differences among the types of sponges and progestogens used. The present results indicate that the self-made vaginal sponge impregnated with 500 mg progesterone has similar effects to the MAP sponge for estrus induction and lambing rate in ewes treated during the non-breeding season.

[1]  H. Ono,et al.  Effects of times of PMSG injection and ram introduction on estrus incidence and lambing rate in ewes treated during the non-breeding season. , 1986 .

[2]  W. Hansel,et al.  A seven-day synchronization method for ewes using medroxyprogesterone acetate (MAP) and prostaglandin F2 alpha. , 1985, Journal of animal science.

[3]  福井 豊,et al.  Effects of injection time of pregnant mare's serum gonadotropin and individual rams on fertility of ewes in a trial of out-of-season breeding. , 1985 .

[4]  M. Thibier,et al.  Control of oestrus in ewe lambs and yearling ewes with medroxyprogesterone acetate and fluorogestone acetate , 1983 .

[5]  H. Ono,et al.  Synchronization of estrus and ovulation in ewes by means of a progestin treatment combined with either PMSG or PGF2.ALPHA.. , 1983 .

[6]  I. Michailidis,et al.  Induced Breeding in Anestrous Milking Ewes of Dairy Breeds: Comparison of Norgestomet, Medroxyprogesterone and Fluorogestone in Two Regimes of PMSG , 1982 .

[7]  M. Boland,et al.  Induction of pregnancy in lactating anoestrous ewes , 1981, The Journal of Agricultural Science.

[8]  Toshiharu Minoda,et al.  Hormonal Induction of Oestrus and Lambing in Anoestrus Ewes , 1981 .

[9]  I. Gordon,et al.  Intravaginal stilboestrol-progestagen treatments in the induction of early breeding in sheep , 1971, The Journal of Agricultural Science.

[10]  I. Gordon.  Induction of early breeding in sheep by standard and modified progestagen-PMS treatments , 1971, The Journal of Agricultural Science.

[11]  E. Roberts,et al.  MPA impregnated intravaginal sponges for the induction of oestrus in anoestrous Border Leicester × Merino ewes. 1. Lactating ewes , 1969 .

[12]  P. Holst,et al.  The evaluation of progesterone- and SC-9880-impregnated intravaginal sponges used with PMS for the induction of breeding in the anoestrous crossbred ewe. , 1967 .

[13]  T. J. Robinson,et al.  The rate of absorption of SC-9880 from impregnated sponges inserted intravaginally in cyclic crossbred ewes. , 1967 .

[14]  T. J. Robinson.  Use of Progestagen-Impregnated Sponges Inserted Intravaginally or Subcutaneously for the Control of the Oestrous Cycle in the Sheep , 1965, Nature.