Evaluar el efecto de la fibra sobre la respuesta ovárica estimulada con hormona foliculoestimulante en vaquillas Holstein mestizas alimentadas con forraje de diferente edad fenológica

Abstract

The study was carried out on the Juticaray farm, located in the Surampalti sector, Déleg canton, Cañar province at an altitude of 3230 meters above sea level. The work evaluated the effect of the administration of 125 International Units (IU) of Follicle-stimulating hormone (FSH) epidurally in eight crossbred Holstein heifers that were fed with pastures of 28 and 42 days of phenological age, on the ovarian response, quantifying the number of antral follicles (AF) observed on the day of the ultrasound-guided aspiration (OPU), the number and quality of cumulus oocyte complexes (COC's) recovered. In the experiment, 4 treatments were established: T0=28-day meadow; T1=28-day pasture + 125 IU of FSH; T2=42-day meadow; T3=42-day meadow + 125 IU of FSH. The meadow contained 80.1% grasses, 7.4% legumes and 6.4% weeds. The chemical analysis determined that the crude fiber in the 28- and 42-day pastures was similar (P>0.005); However, the 28-day pasture had higher percentages of moisture (88.3±0.70) and protein (21.3±0.81) compared to the 42-day pasture (84.9±0.55 and 17.6±0.86 respectively) (P<0.05), this contributed directly to the follicular development of treatment 3, which presented a greater number of follicles between 4-8 mm (116 (74.4%)). The average number of follicles visualized was 19.9 ± 6.68 follicles, of which 76.9% were aspirated (15.3 ± 7.11 follicles aspirated), obtaining a recovery percentage of 59.2% of COC's (11.8 ±7.53 COC's), of which 54.2% were classified as suitable and 45.7% as unsuitable. T3 had 19.1% more recovery than treatment 2 and 22.1% over T1. Additionally, T3 provided 3 times more COC's considered fit compared to those obtained in T2. In conclusion, applying 125 IU influenced the number of follicles that were aspirated, the number and quality of COC's recovered, regardless of the phenological age of the pasture with which the cows were fed.