Authors
Abstract
ABSTRACT: The effect of CIDR and eCG (equine chorionic gonadotrophin) on the dynamics of follicular population and its relationship with P4 plasma concentrations were investigated in cyclic ewes. Fourteen Bergamascia ewes were used, Group 1 (G.1) synchronized by two i.m. injections of PGF2α, and Group 2 (G.2) treated for 14 days with CIDR and 500 IU of eCG at a dispositive withdrawal on day 14. Ovarian follicular dynamics were ultrasonically monitored. All the ovarian follicles with diameter upper than 2 mm were measured, and their relative locations were recorded on an ovarian map in order to follow the sequential development of each individual follicle. Blood samples for P4 determination were collected daily from the day before the second injection of PGF2α (G1) and from the administration of eCG (G2) until day 10 after the ovulation cycle. There were significant (p<0.001) differences in P4 plasma concentrations between the treatments. The CIDR + eCG (500 IU) treatment enhanced the recruitment of smaller follicles and enhanced the maximum diameter and growth rate of large follicles during the first follicular wave.
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References
Aisen, E.G. Reproducción ovina y caprina. In: Freitas, V.J.F.; Rubianes, E. Preparación de las hembras. Detección y control del estro y la ovulación. 1. ed. Inter–Médica: S.A.I.C.I., Buenos Aires, Argentina, p.87-98, 2004.
Amiridis, G. S.; Valasi, I.; Menegatos, I. Luteal stage dependence of pituitary response to gonadotrophin- releasing hormone in cyclic dairy ewes subjected to synchronization of ovulation. Reproduction Fertility and Development, v.17, p.769-774, 2005.
Cardwell, B.E.; Fitch, G.Q.; Geisert, R.D. Ultrasonic evaluation for the time of ovulation in ewes treated with norgestomet and norgestomet followed by pregnant mare’s serum gonadotropin. Journal of Animal Science, v.76, p. 2235-2238, 1998.
Castonguay, F. ; Dufour, J.J. ; Minvielle, F. Follicular dynamics and dominance in Boorola x Finnish Landrace and Boorola x Suffolk ewes heterozygous for the F gene. Journal Reproduction of Fertility, v.89, p.193-203, 1990.
Driancourt M.A, WW Thatcher, M Terqui. Dynamics of ovarian follicular development in cattle during the estrous cycle, early pregnancy and in response to PMSG. Domestic Animal Endocrinology, v.8, p.209- 221, 1991.
Driancourt, M.A.; Gougeon, A.; Royère, D. Reproduction in mammals and man. R.H.F. Hunter, 1993, 305p.
Evans, G.; Robinson, T.J. The control of fertility in sheep: endocrine and ovarian responses to progestagen-PMSG treatment in the breeding season and in anoestrus. Journal Agricultural Science, v.94, p.69-88, 1980.
Godfrey, R. W.; Gray, L.; Collins, J.R. Estrus synchronization of sheep in the tropics using either controlled internal drug release (CIDR) dispensers or prostaglandin F2 (PGF). Journal of Animal Science, v.73, p.232, 1995.
Gonzalez-Añover, P.; Encinas, T.; Veiga-Lopez, A. Effects of breed on follicular dynamics and oestradiol secretion during the follicular phase in sheep. Reproduction Domestic Animal, v.49, p.29-33, 2007.
Hackett, A.J.; Robertson, H.A. Effect of dose and time of injection of prostaglandin F2 in cycling ewes. Theriogenology, 13: 347-351, 1980.
Herrera, H.L.; Feldman, S.D.; Zarco, Q.L. Evaluación del efecto luteolítico de la prostaglandina F2 alfa en diferentes días del ciclo estral de la borrega. Veterinaria México, v.21, p.143-147, 1990.
Lafrance, M.; Goff, A.K. Effect of pregnancy on oxytocin- induced release of prostaglandin F2α in heifers. Biology of Reproduction, v.3, p.1113-1119, 1985.
Latour, D.; Littell, R. Advanced general linear models with an emphasis on mixed models. Version 6.12. Cary: SAS Institute, 1996, 268p.
Liu, X.; Dai, Q.; Rawlings, N.C. Ultrasonographic image attributes of non-ovulatory follicles and follicles with different luteal outcomes in gonadotropin- releasing hormone (GnRH)-treated anestrous ewes. Theriogenology, v.67, p.957-69, 2007.
Leyva, V.; Buckrell, B.C.; Walton, J.S. Regulation of follicular and ovulation in ewes by exogenous progestagen. Theriogenology, 50: 395-416, 1998.
McGinley, R.; Casey, J.H. Analysis of progesterone in unextrated serum; a method using danazol (17 ∞-preg (2,3) isoxasol-17-ol) a bloker of steroid binding to ptoteins. Steroids, v.33, p.127-138, 1979.
McNatty, K.P.; Gibb, M.; Dobson, C. Preovulatory follicular development in sheep treated with PMSG and/or prostaglandin. Journal Reproduction and Fertility, v.65, p.111-123, 1982.
McNeilly, A.S.; Picton, H.M.; B K Campbell, B.K. Gonadotrofic control of follicle growth in the ewe. Journal of Reproduction Fertility, v.43, p.177-186, 1991.
Mihm, M. ; Diskin, M.G. ; Roche, J.F. Regulation of follicle wave growth in cattle. Reproduction Domestic Animal, 31: 531-538, 1996.
Naqvi, S.M.K.; Gulyani, R.; Pmittal, J. Estrus synchronization response in Kheri ewes treated with prostaglandin F Indian Journal of Animal Science, v.68, p.564-565, 1998.
Noel, B.; Bister, J.L.; Pierquin, B. Effects of FGA and PMSG on follicular growth and LH secretion in Suffolk ewes. Theriogenology, 41: 719-727, 1994.
Oyedipe, E.O.; Pathiraja, N.; Gyang, E.O. Effect of dose of pregnant mare serum gonadotrophin on estrus parameters, ovulation rate and peripheral progesterone concentrations inYankasa ewes. Animal Reproduction Science, v.20, p.255-264, 1989.
Pearce, D. T. ; Robinson, T.J. Plasma progesterone concentrations, ovarian and endocrinological responses and sperm transport in ewes with synchronized oestrus. Journal Reproduction Fertility, v.75, p.49-62, 1985.
Pierson, R. A.; Ginther, J.O. Follicular populations during the estrous cycle in heifers. I- Influence of day. Animal Reproduction Science, v.14, p.165-176, 1987.
Ravindra, J. P.; Rawlings, N.C.; Evans, A.C.O. Ultrasonographic study of ovarian follicular dynamics in ewes during the estrous cycle. Journal Reproduction Fertility, v.101, p.501-509, 1994.
Rubianes, E.; Ungerfeld, R.; Viñoles, C. Ovarian response to superstimulatory treatment initiated relative to wave emergency in ultrasonographically monitored ewes. Theriogenology, v.47, p.1479-1488, 1997.
Rubianes, E., Castro, T.; Kmaid, S. Estrus response after a short progesterone priming in seasonally anestrous goats. Theriogenology, v.49, p.356-362, 1998.
Safdarian, M.; Kafi, M.; Hashemi, M. Reproductive performance of Karakul ewes following different oestrous synchronization treatment outside the natural breeding season. South african Journal of Animal Science, v.36, p.229-234, 2006.
Scaramuzzi, R.J, H M Radford. Factors regulating ovulation rate in the ewe. Journal Reproduction Fertility, v.69, p.353-367, 1993.
Schrick, F. N.; Surface, R.A.; Pritchard, J.Y. Ovarian structures during the estrous cycle and early pregnancy in ewes. Biology of Reproduction, v.49, p.1133-1140, 1993.