292 EVALUATION OF THREE PROTEIN SOURCES FOR THE IN VITRO PRODUCTION OF BOVINE EMBRYOS

Abstract

Bovine embryo development in vitro can be affected by many factors, including protein source, which can cause embryo development failure. The use of in vitro culture media supplemented with serum-free compounds could allow a better understanding of embryo requirements during the preimplantation stages by eliminating a highly variable and undefined compound such as serum. The objective of this study was to evaluate the effect of 3 different protein supplements used during IVM, IVF, and IVC on embryo production. Ovaries were collected from slaughtered cows and then aspirated to obtain oocytes for in vitro embryo production procedures. A total of 2056 oocytes were used, from which 685 were processed with maturation medium supplemented with 10% serum replacement (SR) (Gibco Knockout Serum Replacement, Invitrogen, Carlsbad, CA, USA), a defined serum-free formulation (TCM-199 + SR), fertilization medium with SR (TALP + SR), and culture medium with SR (SOF + SR). These were compared with 675 and 696 oocytes processed with the same IVM, IVF, and IVC media, but supplemented with 10% FCS or 10% heat-inactivated estrous cow serum (ECS), respectively. Data obtained from the variables studied were processed by analysis of variance and means were compared by Tukey’s test. The percentages of embryos produced with FCS (52.4%) and ECS (52.7%) were significantly higher compared with the percentage obtained with SR (41.5%) (P < 0.05). The percentages of morulae were similar in the groups supplemented with FCS (36.5%) and SR (36.7%), but significantly higher than the percentage in the ECS group (26.9%) (P < 0.05). For blastocysts, the percentages of embryos developed with FCS (35.2%) and ECS (35.6%) were significantly higher than that obtained with SR (29.2%) (P < 0.05). When evaluating expanded blastocysts, the percentage obtained in the FCS (45.9%) group was significantly higher than that in the ECS group (33.2%), and this was significantly higher than that obtained in SR (21%), with all these differences being significant (P < 0.05). It is concluded that it is possible to produce bovine embryos in vitro using FCS, ECS, or SR as supplements in IVM, IVF, and IVC media. Significant differences were found in different embryo stages, with the highest proportion of embryos developing with the addition of FCS, whereas supplementation with SR only improved the production of morulae. We thank Consejo Nacional de Ciencia y Tecnologia (CONACYT-Mexico) for the graduate student’s scholarship.