Oocytes population and development competence of Bali cattle embryo in vitro with different ovarian reproductive statuses

The present study aims to determine the potential of Bali cattle ovaries as sources of oocytes forin vitro embryo production based on different ovarian reproductive statuses. The ovaries were groupedinto 4 categories: ovaries with no corpus luteum and dominant follicles (CL-DF-), those with corpusluteum and no dominant follicles (CL+DF-), those without corpus luteum but with dominant follicles(CL-DF+), and those with corpus luteum and dominant follicle (CL+DF+). The oocytes were collectedvia the slicing technique and grouped into 4 grades (a, b, c, and d). The oocyte’s maturation wasperformed using tissue culture medium 199 basic media. A drop sample (10–15 oocytes/drop) coveredwith mineral oil was then placed in a 5% CO2 incubator at a temperature of 38.5 ℃ for 24 h. Then, the samples were fertilized in 80 μL of fertilization medium with a final spermatozoa concentration of1.5×106 spermatozoa/mL. After 5–6 h of in vitro fertilization, the oocytes were washed four times usingthe Charles Rosenkrans 1aa (CR1aa) medium. Then, the samples were cultured using the CR1aa as abase medium. The results showed no significant difference (p>0.05) for the 4 groups based on theoocyte population collected from one pair ovary as well as the number of oocytes that were suitablefor maturation. However, group CL-DF+ showed a significant difference (p<0.05) in the rate of nuclearmaturation (80.00±12.84), fertilization rate (80.00±4.72), and the ability of embryo development(60.19±22.45) when compared to group CL-DF-, CL+DF-, and CL+DF+. This study determines thatthe oocyte population of Bali cattle ovary pairs and oocytes quantity that are fit for maturation isnot influenced by the reproductive status of the ovaries. However, the level of nuclear maturation,fertilization, and the ability of embryo development is higher in the ovaries without corpus luteum butwith dominant follicles.