EFECTO INHIBITORIO DE LA PROGESTERONA SOBRE EL DESARROLLO DE LA ONDA FOLICULAR EN LLAMAS

Abstract

The effect of the exogenous progesterone (P4) on the development of follicular waves in llamas was studied in twenty-five females. According to dose and regimen for P 4 administration, animals were allocated to 5 groups (n=5): 00 (control group ), G 1 (30 mg P /day for 2 days); G2 (30 mg P/day for 4 days); G3 (50 mg P /day for 2 days) and G4 (50 mg P /da y for 4 days ). Development of dominant ():. 7 mm) and subordinated follicles (>3 mm and < 7 mm) were monitored daily by transrectal ultrasonography. The minimun size reachedbythedorninantfollicleingroupsGl (4.6±0.9mm), G3(5.1±1.5 mm) andG4(5.3 ± 1.6 mm) were smaller (P< 0.05) than group 00 (8.5 ± 1.0 mm). The whole follicular regression of the dominant follicle in groups G 1 (5.5 ± 2.0 mm), G2 (5.9 ± 1.4 mm) and G3 (5.3 ± 3. 3 mm) were larger (P< 0.05) than group 00 (0.9 ± 1.4 mm). The number of subordinated follicles hada significative increase (P< 0.05) in groups G 1 and G4, on days 2 and 3 in relation to days 7 and 8 post-treatment. Results demonstrate that exogenous progesterone inhibits the development of the dominant and subordinate follicles in lla-mas during treatment days; however, immediately after the end of the treatment, the · number of subordinate follicles increases, due to the regression of the dominant follicle in order to allow the emergence of a new follicular wave.