Abstract
The objective of the current study was to assessment the effect of L-Carnitine as a stimulant of lipid catabolism in vitro maturation (IVM) and in vitro culture (IVC) media on IVM rate (nuclear maturation) and embryonic development. A total of 495 oocytes were assigned into two groups; the control group, oocytes matured in TCM-199 medium; L-Carnitine group oocytes matured in TCM-199 medium supplemented with L-Carnitine (0.5mg/ml). After that 250 oocytes were stained with Hoechst 33342 then with Nile Red dye. The nuclear maturation and oocyte lipid content were determined under a fluorescence microscope. The other matured oocytes were incubated for cell activation by Thimerosal and DL- Dithiothreitol (DDT). Potential zygotes were incubated in vitro culture 1 and 2, the stained embryos were counted and evaluated for morula and blastocyst stages. The Metaphase II rates were 16.2% and 42.1% in the control group and L-carnitine group, respectively. Overall, 9.3% and 14.9% of the oocytes reached at least the MI stage in the control group and L-carnitine group respectively. The addition of L-carnitine in IVM media resulted in a significant decrease in the amount of lipid in cat oocyte. Moreover, the incubation of matured oocytes of the L-carnitine group in IVC1 lead to significant increase in cleaved cells 29.4% in comparison with the control group 15.4%. The incubation of cleaved cell of the L-carnitine group in IVC2 lead to decrease significantly in degenerated cells 12.5 % compared to the control group 42.9% while caused an increase significantly in morula 50% compared to the control group 33.3% and blastocyst 37.5% comparison with the control group 23.8%. In conclusion, the use of L-Carnitine as a supplement in IVM and IVC media decrease lipid content of cat oocyte and subsequent enhance the nuclear maturation, cell activation of cat's embryo, and embryonic development.

Key words: L-carnitine; Domestic cat; Oocyte; In vitro maturation; Embryo