Development of a simple, portable carbon dioxide incubator for in vitro production of bovine embryos
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The objective of this study was to develop a simple and portable CO2 incubator using effervescent granules EG.and to examine the effect of negative and positive air pressure for in vitro maturation IVM., fertilization IVF.and culture IVC.of bovine oocytes. In experiment 1, cumulus-oocyte complexes COCs.were matured 22 h., fertilized 5 h.and cultured 7 days. using 0.25, 0.5 or 1.0 g of EG per 0.6 l added to maintain an optimum level of CO2 approximately 3, 6 or 12%, respectively.for in vitro production of embryos. Control oocytes, zygotes and embryos were cultured in a standard CO2 incubator. The blastocyst production rates observed on Days 7 to 9 after insemination were 20.5"4.2%, 18.5"3.9% and 28.7"5.1% for the 0.25 g EG, 0.5 g EG treatments and control, respectively. These rates were significantly higher P-0.05.than that of the 1.0 g EG treatment 8.7"2.6%.. The number of cells in the inner cell mass ICM.and trophectoderm TE.produced from blastocysts using the control procedure were 40.8"2.9 and 81.2"5.3, respectively, and were higher P-0.05.compared to the 0.50 g EG 34.6"2.9 and 66.8"5.7.and 1.0 g EG treatments 33.4"3.4 and 67.2"7.3.. In experiment 2, COCs were placed in a small box with 0.25 g of EG so that the effects on IVM, IVF and IVC of positive or negative air pressure could be compared. The blastocyst production rate observed in the negative air pressure treatment 29.6"4.6%.was higher P-0.01. than that of the positive air pressure treatment 6.2"1.5%.or the normal treatment pressure P-0.05; 18.7"4.2%. but did not differ from that of the control 30.7"4.4%.. These results indicate that this simple type of incubator with negative air pressure can be successfully used for in vitro production of bovine embryos and could be used at the field level. q1999 Elsevier Science B.V. All rights reserved.