Research Information System
SLOVENIAN VETERINARY RESEARCH, vol.61, 2024 (SCI-Expanded)
: This study aimed to compare the effects of a single dose of GnRH or hCG
administered at the beginning of the short-term oestrus synchronization protocol on
≥4 mm diameter follicles in Saanen goats during the breeding season. The goats estrus cycles were synchronized with intravaginal sponges containing 60 mg of medroxyprogesterone acetate for five days. Additionally, 1 ml of physiological saline solution
(control-group; n=30), 0.004 mg of buserelin acetate (GnRH-group; n=31) or 150 IU of
hCG (hCG-group; n=31) were injected intramuscularly to the goats during the sponges
insertion. Transrectal ultrasonographic examination was performed immediately before and 24 h after intravaginal sponge application into all goats and follicles with a
diameter of ≥4 mm in the ovaries were counted. Blood samples were collected on the
same days to determine serum progesterone (P4) and estradiol (E2) concentrations.
At the first ultrasonographic examination, the percentages of ≥4 mm diameter follicles
were 56.66% (17/30), 54.83% (17/31) and 70.96% (22/31) in the control, GnRH and hCG
groups, respectively. The percentage of goats with reduced follicle diameters 24 h later
was 29.41% (5/17), 52.94 (9/17) and 59.09% (13/22) in the same groups, respectively.
The mean regression rates of follicle diameters between days 0 and 1 in each group
were significantly different (P<0.05). Serum E2 concentrations were significantly different (P<0.05) between days 0 and 1 in hCG group. There were no differences in serum
E2, P4 concentrations and mean regression rates in follicle diameters between days 0
and 1 for all groups. As a result, a significant relationship between the administration
of hCG or GnRH and the reduction of large follicle diameters could not be established.