title: Follicular and endocrinological turnover associated with GnRH induced follicular wave synchronization in Indian crossbred cows.
abstract: The goal of this study was to record the hormonal and follicular turnover in Jersey crossbred cows when subjected for follicular wave synchronization using GnRH. Six healthy, non-lactating and regularly cycling Jersey crossbred cows (5-6 y) were used for the study. In the control group, the follicular wave pattern was ultrasonographically investigated in 18 cycles (3 cycles/cow). In the treatment group, GnRH analogue (buserelin acetate 10 μg im) was administered on Day 6 of the cycle and follicular wave pattern was studied in 12 cycles (2 cycles/animal). Follicular population was categorized based on their diameter Class I, ≤5 mm; Class II, >5-<9 mm; Class III, ≥9 mm) and the number of follicles in each category was determined on Day 6, Day 8 and Day 10. Plasma FSH and progesterone concentrations were estimated in both control and treatment groups. Out of 18 estrous cycles studied, 14 cycles (77.8%), three cycles (16.7%) and one cycle (5.6%) exhibited three-, two- and four-follicular waves per cycle, respectively. It was evident that the DF of Wave I established its dominance and was in the growing phase by Day 6 of the estrous cycle in all the normally cycling crossbred cows. The DF ovulated in all the animals (100%) in the mean interval of 27.7 ± 0.2 h after GnRH administration. A synchronized homogenous group of follicles emerged two days after GnRH injection (Day of 8.0 ± 0.0) in all the animals (100%). The combination of LH surge induced ovulation of DF (abrupt termination of Wave I) and FSH surge stimulated homogenous recruitment of Class I follicles, led to a synchronized emergence of follicular wave. All the GnRH treated cows had three follicular waves because of early emergence and short period of dominance of Wave II DF.
authors.affiliation: Department of Animal Biotechnology, Madras Veterinary College, Chennai-600 007, Tamil Nadu, India. drsatheshkumar6@rediffmail.com
authors.forename: S
authors.initials: S
authors.lastname: Satheshkumar
authors.forename: A
authors.initials: A
authors.lastname: Subramanian
authors.forename: T G
authors.initials: TG
authors.lastname: Devanathan
authors.forename: D
authors.initials: D
authors.lastname: Kathiresan
authors.forename: C
authors.initials: C
authors.lastname: Veerapandian
authors.forename: A
authors.initials: A
authors.lastname: Palanisamy
mesh_terms: D000818:Animals; D002417:Cattle; D004971:Estrus / Q000187:drug effects*; D004973:Estrus Synchronization; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D006824:Hybridization, Genetic; D007194:India; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000187:drug effects*; D010060:Ovulation / Q000187:drug effects; D014463:Ultrasonography
chemical_list: D007987:Gonadotropin-Releasing Hormone