518. RELATIONSHIP BETWEEN THE OVARIAN STATUS ON THE INITIATION DAY OF SUPEROVULATION AND SUPEROVULATORY RESPONSES IN CATTLE

Abstract

The purpose of this experiment was to determine the influence of the ovarian status on the initiation day of superovulation (d 0) on superovulatory responses in terms of the number of large follicles (≥7mm) at estrus (d 4) and CL 7 days after estrus (d 11). Ultrasonography was performed on d 0, 4 and 11of the experiment. Animals conventionally superovulated (400 mg Folltropin-V) between d 8 to 12 of the estrous cycles and 102 superovulation cycles were considered in the present experiment. Data were analyzed using GLM procedure of the SAS. In these cases, the number of follicles was determined in each of the 2 studied classes (SF, 4 to 6 mm; and LF, ≥7mm) on d 0. Subsequently, each of these classes was divided into two subgroups (Low, High) based on the number of follicles observed on d 0 (Table 1). The number of LF at estrus in each of the 2 studied classes (Low vs. High) were (13.02±1.02 vs. 19.7±1.69, p<0.01; and 16.23±1.59 vs. 14.75±1.48, p>0.1) and the number of CL on d 11 were (9.75±0.57 vs. 12.75±0.98, p<0.01; 10.91±0.8 vs. 10.85±0.65, p>0.1). Therefore, the ovarian status on d 0 in terms of the number of SF affected the number of LF (d 4) and CL (d 11). In addition, the number of superovulatory cycles with low number of SF was 2 times more than the ones with a high number of SF on d 0; also 49 out of 102 superovulatory cycles had at least 2 LF on the initiation day of superovulation (Table 1). These results suggested that follicular puncture 1–2 days before a conventional superovulation treatment may increase the superovulatory responses.