EMBRYO TRANSFER RESULTS OBTAINED WITH FRESH AND FROZEN EMBRYOS IN THE REGION OF AZUERO (Tropical dry forest). 1999.

Abstract

At the present study 73 embryos were transferred, from which 25 were fresh embryos and the rest (48) were frozen embryos imported from Australia. Fresh embryos were collected from superovulated cow under farm conditions. Frozen embryos were thawed in three steps (10 minutes each) in decreasing glycerol concentrations + constant amount of sucrose (1: 6% glycerol + 10.3% sucrose; 2: 3% glycerol + 10.3% sucrose and 3: 6% glycerol + 10.3% sucrose). All embryos were transferred in the same recipients herd (F-1, Holstein x Zebu heifers, ages between 22 to 30 month and average body weigth of 400 kg), keep under the same management and feeding conditions. Recipient synchronization was +1 and 0 in relation to superovulatory estrous in donors cows mean while embryo age was in all cases 7 days. The variations factors studied were: embryo source (fresh or frozen), period of the year (I: January to May and II: June to December) and synchronization time (day + 1 or 0). The pregnancy results were 31.25% with frozen embryos (15/48) and 60% (15/25) with fresh embryos (P<0.05). According to the period of the year in which transfers were performed results shown in period I: 51.52% vs II: 32.5%, correlating source of embryos and period of the year, frozen embryos shown significant differences (P<0.05) between periods (I: 45% vs II: 21.43%); however, fresh embryos did not show the same behavior (I: 61.54% vs II: 58.33%). In relation to the source of embryo and recipient donor synchronization nevertheless nor statistical differences were proved a similar mathematical tendency was observed as in the previous results for source of embryo period of the year. The pregnancy results were 40% (6/15) and 27.3% (9/33) for frozen embryos in days + 1 and 0, respectively; on the other hand, fresh embryos transferred on days + 1 risk 75% (6/8) as well as 69.2% (9/13) obtained for those transferred on day 0. We concluded that for increasing embryo transfer results under the Azuero climatic conditions in Panama, transfers should be performed during the months of January to May and is proposed to study the use of embryo recipients with one day in advance (day + 1) in reference to the superovulatory estrous in the embryo donors.