Effect of Time-Lapse Incubation System on In Vitro Development of Alpaca Embryos

Currently, incubators with a time-lapse system are widely used for in vitro embryo production in several species, however, their effect on alpaca embryo development compared to conventional incubators remains unknown. The aim of this study was to compare early in vitro embryo development in alpacas using a time-lapse incubator system versus a conventional incubator. Ovaries were obtained from a slaughterhouse and 1048 cumulus-oocyte complexes (COCs) were collected and in vitro matured for 26 h in either a time-lapse system (n = 542) or a conventional incubator (n = 542). All the matured COCs were fertilised for 24 h with fresh spermatozoa recovered from epididymis obtained from the slaughterhouse. The presumptive zygotes in both systems were cultured in a commercial one-step culture medium, and the embryo development was evaluated at 48, 120 and 168 h after fertilisation. Our results showed no differences in maturation rates between the time-lapse system and the conventional incubator (79.9% vs. 55.0%, p = 0.080). Cleavage rates at 48 h were also similar between the time-lapse and conventional systems: 20.5% vs. 20.8% for embryos at the two- to four-cell stage, and 6.0% vs. 7.0% for embryos above the four-cell stage (p > 0.05). At 120 h after fertilisation, the percentage of embryos were more evenly distributed across all stages (below eight-cell, eight-cell and above eight-cell stages) in both systems (p > 0.05). At 168 h, no differences in the blastocyst rates and blastocyst quality were observed between the time-lapse and conventional systems. In conclusion, in vitro embryo production in alpacas can be successfully carried out using the time-lapse incubation system or a conventional incubator with comparable results. Further study would focus on the correlation between the developmental patterns and the quality of alpaca embryos, as well as the comparison of in vivo embryo development between the two incubation systems.