409 SUPERSTIMULATED BOVINE DONORS INSEMINATED WITH SEMEN WITH DIFFERENT LINEARITY EVALUATED BY COMPUTER-ASSISTED SPERM ANALYSIS

Abstract

There is a highly significant relationship between semen quality and the percentage of fertilized ova and transferable embryos in superovulated donors (Stroud B and Hasler JF 2006 Theriogenology 65, 65-76). Computer-assisted sperm analysis (CASA) provides an objective and highly repeatable system for sperm analysis. It has been observed that linearity (LIN) measured by CASA has a high correlation with fertility (Foote RH et al. 1998 Theriogenology 49, 871-879). In the present report, retrospective analysis was done to determine the effect of sperm linearity as assessed by CASA on the number of ova and viable embryos recovered from superstimulated cows. This research was carried out using different breeds of donors (n = 150, 80% Angus) during the last 5 years in an embryo transfer center in Buenos Aires province, Argentina. Donors with a CL received an intravaginal progesterone device (DIB^®, Syntex, Buenos Aires, Argentina), 2 mg of 17? estradiol, and 50 mg of progesterone (Rio de Janeiro, Brazil), i.m. on the same day. On Day 4 after DIB^® insertion, superstimulatory treatment was initiated as a decreasing dose regimen of FSH i.m. (Pluset^®, Callier, Spain, or Folltropin^®, Bioniche Animal Health, Inc., Belleville, Ontario, Canada) every 12 h during 4 days. On Day 6, DIB^® devices were removed and cows were administered cloprostenol (2 mL) twice at 12-h intervals. When estrus was detected, donors received GnRH (2 mL i.m. Dalmarelin^®, Von Franken, Buenos Aires, Argentina) and were inseminated 12 and 24 h thereafter. Semen was thawed in a water bath at 37°C for 1 min. Before insemination, every semen dose was evaluated for motility characteristics using the IVOS Sperm Analyzer (Hamilton Thorne Biosciences, Beverly, MA, USA). Two chambers of 20-(im depth and 5 fields per chamber were analyzed (30 frames/0.5 s for each field). According to CASA results, 3 groups were defined based on LIN: Group 1 = <50%; Group 2 =≥50% and <60%; and Group 3 =≥60%. Seven days later, embryo collection was performed and ovarian response was evaluated by transrectal ultrasonography to assess number of CL + anovulatory follicles. Ova/embryos were evaluated and classified according to the IETS manual. Kruskal-Wallis test was used to compare variables among groups, and results are shown in Table 1. There was a significant difference between Groups 1 and 3 for total number and percentage of viable embryos. More embryos were recovered from donors inseminated with higher LIN semen. Also, there was a significant difference between Group 1 and both Groups 2 and 3 in the number of total fertilized ova, percentage of fertilized ova, and percentage of unfertilized ova. The present results suggest that insemination of donors with semen of high LIN results in higher fertilization rates and number of viable embryos.

Table 1.  Number of fertilized ova and viable embryos of donor cows inseminated with semen with different linearity