title: Ovulatory follicle dysfunction in lactating dairy cows after treatment with Folltropin-V at the onset of luteolysis.
abstract: The objective was to examine growth of the ovulatory follicle after FSH (Folltropin-V; Bioniche Animal Health, Belleville, Ontario, Canada) was given at the onset of induced luteolysis during a synchronization of ovulation protocol. Using GnRH or hCG for inducing ovulation enabled assessing ovulatory follicle responsiveness to an endogenous versus exogenous surge of LH activity. At 8 to 10 days after estrus (synchronized estrus = Day 0), lactating dairy cows received an Eazi-Breed CIDR (Pfizer Animal Health) plus 100 μg GnRH. After 7 days, controlled internal drug release devices (CIDRs) were removed, cows were given 500 μg cloprostenol, and then randomly allocated to receive 80 mg Folltropin-V (FSH; N = 19) or 4 mL sterile saline (SAL; N = 16). After 49 hours, FSH and SAL cows were randomly allocated to receive 100 μg GnRH or 3000 IU hCG. Five cows ovulated 30 to 42 hours (38.4 ± 1.2 hours) after FSH treatment. In the remaining FSH (N = 14) or SAL (N = 16) cows, ovulatory follicle size was similar at CIDR removal (14.5 ± 0.6 and 14.7 ± 0.6 mm, respectively; P = 0.85) and when GnRH/hCG was given (16.6 ± 0.6 and 17.7 ± 0.6 mm, respectively; P = 0.23). Estradiol-17β concentrations were lower in FSH cows at 36 and 49 hours after CIDR removal (FSH by time interaction, P < 0.005). After GnRH or hCG treatment, four FSH cows failed to ovulate. In cows exhibiting ovulation, the last recorded size of the ovulatory follicle was not influenced by FSH (18.1 ± 0.9 and 17.5 ± 0.6 mm for FSH and SAL, respectively; P = 0.59) or hormonal induction approach (18.4 ± 0.9 and 17.2 ± 0.7 mm for GnRH and hCG, respectively; P = 0.29). The interval from onset of luteolysis to ovulation and pharmaceutical induction to ovulation was shorter in FSH cows given GnRH (FSH by pharmaceutical inducer [GnRH vs. hCG] interaction; P = 0.01). Cows receiving GnRH had an LH surge; hCG-treated cows did not. Maximum LH concentrations were greater (P < 0.04) in SAL versus FSH cows after GnRH treatment (10.9 ± 1.2 vs. 6.7 ± 1.4 ng/mL, respectively). In three FSH cows failing to ovulate after GnRH treatment, the maximum LH concentration was <4 ng/mL. When analyzed from GnRH treatment, average time to LH maximum concentration was similar (P = 0.50) to values obtained in cows receiving FSH and GnRH and SAL and GnRH (1.7 ± 0.2 vs. 1.9 ± 0.1 hours, respectively). Interval to maximum hCG concentrations was shorter (P = 0.02) for cows receiving SAL versus FSH (8.0 ± 0.8 and 10.0 ± 0.8 hours for SAL and FSH, respectively). Ovulatory dysfunction of this magnitude highlighted the lack of suitability of Folltropin-V at a dose of 80 mg at the time of induction of luteolysis in fixed timed AI protocols.
authors.affiliation: Department of Animal Science, The University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: J O
authors.initials: JO
authors.lastname: Giordano
authors.forename: J L
authors.initials: JL
authors.lastname: Edwards
authors.forename: F A
authors.initials: FA
authors.lastname: Di Croce
authors.forename: D
authors.initials: D
authors.lastname: Roper
authors.forename: N R
authors.initials: NR
authors.lastname: Rohrbach
authors.forename: A M
authors.initials: AM
authors.lastname: Saxton
authors.forename: G M
authors.initials: GM
authors.lastname: Schuenemann
authors.forename: T M
authors.initials: TM
authors.lastname: Prado
authors.forename: F N
authors.initials: FN
authors.lastname: Schrick
mesh_terms: D000818:Animals; D002417:Cattle; D006063:Chorionic Gonadotropin / Q000008:administration & dosage / Q000494:pharmacology; D003612:Dairying; D004334:Drug Administration Schedule; D005260:Female; D005300:Fertility Agents, Female / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage* / Q000009:adverse effects; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology; D007774:Lactation / Q000097:blood / Q000187:drug effects / Q000502:physiology; D007986:Luteinizing Hormone / Q000097:blood; D003341:Luteolysis / Q000097:blood / Q000187:drug effects / Q000502:physiology; D006080:Ovarian Follicle / Q000187:drug effects* / Q000503:physiopathology; D010062:Ovulation Induction / Q000379:methods / Q000662:veterinary; D034445:Ovulation Inhibition / Q000187:drug effects
chemical_list: D006063:Chorionic Gonadotropin; D005300:Fertility Agents, Female; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone