γ-LA-Supplementation to IVC for IVP Bovine Embryos

The present study aimed to examine the effects of ${\gamma}$-linolenic acid (GLA) supplementation to in vitro culture (IVC) medium on in vitro developmental competence, freezability and morphology of in vitro matured and fertilized bovine embryos. In vitro produced (IVP) bovine zygotes were cultured in IVC medium supplemented with 0 (negative control), 15, 31, 62, 125, 250, 500 or 1,000 ppm GLA, 250 ppm linoleic acid albumin (LAA) and without any supplement as a control. Day 6 blastocysts derived from culture control were cultured in IVC medium containing either 62, 250 GLA or 250 LAA for 24 h, and at Day 7 were subjected to freezing or morphological examination by electron microscope. GLA 15 showed a tendency to have a higher cleavage rate at Day 2 (70.3%) than other groups. The hatching rate at Day 9 in LAA (38.2%) was significantly higher than the control and all treatment groups (p<0.05), while the blastocyst rate in LAA (32.4%) did not differ from those of 15 (30.5%), 31 (27.1%), and 62 GLA (33.1%) or the control (35.1%). GLA in concentrations of 125, 250, 500, and 1,000 ppm had significantly detrimental effect on the blastocyst rate compared to 15, 31 and 62 ppm GLA, LAA, and control groups (p<0.05). In contrast, the highest post-thaw survival rate (100%) was observed in the control group (p<0.01). Large lipid droplets were observed in the cytoplasm of trophoblastic cells, even in the control, but were abundant in GLA groups. Taking the results of the study into consideration, the addition of GLA to the culture medium for IVP bovine embryos at the dose of 15 ppm increased the developmental competence of zygotes and enhanced the cleavage rate up to Day 2. However, blastulation rate and post-thaw survival were not increased when GLA was added to the culture media.