Follicular status at initiation day of the superovulatory treatment influences the superovulatory responses in cattle
The aim of this study was to investigate superovulatory responses of cows according to the status of various follicular classes on day 0 (day of initiation of the superovulatory treatment). One hundred and two superovulation cycles were selected. The animals were superstimulated between days 8 and 12 of oestrous cycle with 400 mg of Folltropin-v given in decreasing doses over a 4 d period and luteolysis was induced with two intramuscular injections of cloprostenol. The ovaries of all cows were examined by ultrasonography on day 0, at oestrus, and on day 7 after oestrus. The results showed that the follicular and ovulatory responses were higher (P<0.0l ) in cows that were superovulated in the presence of a high (≥6) number of follicles than in the presence of a low (≤5) number of follicles 4 to 6 mm in diameter. Follicular and ovulatory responses did not differ according to the status of the three other follicular classes studied. Additionally, the mean numbers of fertilised structures and unfertilised ova were not influenced by the status of any of the follicular classes studied. In conclusion, the follicular and ovulatory responses were influenced by the status at initiation day of the superovulatorv treatment.
- 1. Adams G.P., Kot K., Smith C.A., Ginther O.J.: Selection of a dominant follicle and suppression of follicular growth in heifers. Anim Reprod Sci 1992, 30, 259-271.
- 2. Bungarts L., Niemann H.: Assessment of the presence of a dominant follicle and selection of dairy cows suitable for superovulation by a single ultrasound examination. J Reprod Fertil 1994, 101-3, 583-591.
- 3. Grasso F., Guilbault L.A., Roy G.L., Lussier J.G.: Ultrasonographic determination of ovarian follicular development in superovulated heifers pretreated with FSH-P at the beginning of the estrous cycle. Theriogenology 1989, 31, 1202-1219.
- 4. Guilbault L.A., Grasso F., Lussier J.G., Rouiller P., Matton P.: Decreased superovulatory responses in heifers superovulared in the presence of a dominant follicle. J Reprod Fertil 1991, 91, 81-89.
- 5. Guilbault L.A., Lussier J.G., Grasso F.: Interrelationships of hormonal and ovarian responses in superovulated heifers pretreated with FSH-P at the beginning of the estrous cycle. Theriogenology 1992, 37, 1029-1040.
- 6. Guilbault L.A., Rouiller P., Matton P., Glencross R.G., Beard A.J., Knight P.G.: Relationships between the level of atresia and inhibin content (α subunit and α-ß dimer) in morphologically dominant follicle during their growing and regressing phases of development in cattle. Biol Reprod 1993, 48, 268-276.
- 7. Huhtinen M., Rainio V., Aalto J., Bredbacka P., MakipTanila A.: Increased ovarian responses in the absence of a dominant follicle in superovulated cows. Theriogenology 1992, 37, 457-463.
- 8. Kawamata M.: Relationships between the number of small follicles prior to superovulatory treatment and superovulatory response in Holstein cows. J Vet Med Sci 56, 965- 967.
- 9. Kohram H., Bousquet D., Durocher J., Guilbault L.A.: Alteration of follicular dynamics and superovulatory responses by gonadotropin releasing hormone and follicular puncture in cattle. Theriogenology 1998, 49, 1165-1174.
- 10. Lima W. M., Vieira A.D., Thaller Neto A., Mezzalira A., Matos R.C., Gregory R.M.: Improved superovulatory response in beef cattle following ovarian follicular ablation using a simplified transvaginal device. Anim Reprod Sci 2006, 100, 364-370.
- 11. Matton P., Adelakoun V., Couture Y., Dufour J.J.: Growth and replacement of the bovine ovarian follicles during the estrous cycle. J Anim Sci 1981, 52, 813-820.
- 12. Monniaux D., Chupin D., Saumande J.: Superovulatory responses of cattle. Theriogenology 1983, 19, 55-81.
- 13. Moor R.M., Kruip Th.A.M., Green D.: Intra-ovarian control of folliculogenesis: Limits to superovulation? Theriogenology 1984, 21, 103-116.
- 14. Murphy B.D., Mapletoft R.J., Manns J., Humphrey W.D.: Variability in gonadotrophin preparations as a factor in a superovulatory response. Theriogenology 1984, 21, 117- 125.
- 15. Pierson R.A., Ginther O.J.: Follicular population during the estrous cycle in heifers. I. The influence of day. Anim Reprod Sci 1987, 14, 165-176.
- 16. Pierson R.A., Ginther O.J.: Follicular population during the estrous cycle in heifers. II. Influence of right and left sides and intra-ovarian effect on the corpus luteum. Anim Reprod Sci 1987, 14, 177-186.
- 17. Rajakoski E.: The ovarian follicular system in sexually mature heifers with special reference to seasonal, cyclical and left-right variations. Acta Endocrinol 1960, 52 (Suppl), 1-68.
- 18. Rajamahendran R., Waalton J.S.: Follicular development and corpus luteum formation in postpartum dairy cattle. 11th International Congress on Animal Reproductive and Artificial Insemination 1988, 2, 60-62.
- 19. Romero A., Albert J., Brink Z., Seidel G.E. (jr). Number of small follicles in ovaries after superovulation response in cattle. Theriogenology 1991, 35, 265.
- 20. Savio J.D., Keenan L., Boland M.P., Roch J.F.: Pattern of growth of dominant follicle during the estrous cycle in heifers. J Reprod Fértil 1988, 88, 663-671.
- 21. Sirois J., Fortune J.E.: Ovarian follicle dynamic during the estrous cycle in heifers monitored by realtime ultrasonography. Bio Reprod 1988, 39, 308-317.