title: Alteration of follicular dynamics and superovulatory responses by gonadotropin releasing hormone and follicular puncture in cattle: a field trial.
abstract: A field experiment was conducted to determine the influence of follicular alteration on superovulatory responses. Ultrasonography was performed once daily over 4 d prior to gonadotropin treatment (Day 0), on the day of estrus during superstimulation, and on the day of embryo collection to monitor follicular development. Animals were superstimulated between Days 8 and 12 of the estrous cycle. Follicular status was altered 2 d prior to initiation of superstimulation (Day 0) with GnRH (Cystorelin, 200 micrograms i.m.) administered with (GnRH-puncture group, n = 31) or without (GnRH-no puncture group, n = 52) concomitant removal of the largest follicle by follicular aspiration. Responses were compared with those of an untreated control group superovulated 8 to 12 d after estrus (n = 102). The proportion of animals with a high number (> or = 2) of large follicles (> = 7 mm) on Day 0 was lower (P < 0.001) in the 2 GnRH-treated groups than in the control group, while the increase in the number of medium size follicles (4 to 6 mm) on Day 0 was greater (P < 0.02) in the GnRH-puncture group. During superstimulation, the proportion of superovulatory cycles with a high follicular (> or = 10 follicles) response was similar in the control and GnRH-no puncture groups. Within the GnRH-treated animals, follicular and ovulatory responses were greater in the GnRH-puncture than in the GnRH-no puncture group (P < 0.001 to P < 0.02). Despite these changes in follicular and ovulatory responses, however, the mean number of embryos produced did not differ (P < 0.1) among treatments (4.3 +/- 0.4, 3.7 +/- 0.7, and 5.4 +/- 0.8 in control, GnRH-no puncture, and GnRH-puncture groups, respectively). This was due primarily to an increase in the mean numbers of unfertilized ova (P < 0.005) and in degenerated embryos (P < 0.06) in the GnRH-puncture group. Results indicate that the beneficial effects of treatment with GnRH and follicular puncture 2 d prior to superstimulation on follicular and ovulatory responses were limited by an increase in the number of unfertilized ova and degenerated embryos.
authors.affiliation: CRBR, Département des sciences animales, Université Laval, Ste-Foy, Québec, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Kohram
authors.forename: D
authors.initials: D
authors.lastname: Bousquet
authors.forename: J
authors.initials: J
authors.lastname: Durocher
authors.forename: L A
authors.initials: LA
authors.lastname: Guilbault
mesh_terms: D000818:Animals; D002417:Cattle / Q000196:embryology / Q000502:physiology*; D003008:Cloprostenol / Q000494:pharmacology; D005314:Embryonic and Fetal Development; D004958:Estradiol / Q000032:analysis; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007315:Insemination, Artificial / Q000662:veterinary; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology*; D010053:Ovary / Q000000981:diagnostic imaging; D011374:Progesterone / Q000032:analysis; D011677:Punctures / Q000662:veterinary; D011863:Radioimmunoassay / Q000662:veterinary; D011897:Random Allocation; D013480:Superovulation / Q000187:drug effects / Q000502:physiology*; D014463:Ultrasonography
chemical_list: D007987:Gonadotropin-Releasing Hormone; D003008:Cloprostenol; D011374:Progesterone; D004958:Estradiol