Comparisons of culture of Chinese Meishan with Yorkshire pig embryos in vitro: Effects of protein supplementation and development

Three experiments were designed to evaluate modifications in a culture system for Chinese Meishan pig embryos. The objective of Experiment I was to compare in vitro development of Meishan embryos recovered at the four and eight-cell (EARLY) and compact morula and blastocyst (LATE) stages in a, Whitten's based medium supplemented with either 5.0 per cent fetal bovine serum (W-FBS) or 0.4 per cent bovine serum albumin (W-BSA). Embryos were flushed from reproductive tracts of Meishan females with Dulbecco's phosphate buffered saline (D-PBS), randomized to treatment and cultured in 50 μl drops under paraffin oil at 39C in a humidified 5.0 per cent CO₂ in air environment. In addition, EARLY embryos within each treatment were cultured with one or four embryos per drop. Within treatment, no difference was detected between one and four embryos per drop for development to any stage (P>0.30). Culture of EARLY embryos indicated that W-BSA supported greater development into compact morulae and blastocysts than W-FBS (P<0.01), but neither treatment permitted hatching from the zona pellucida. More LATE embryos developed into hatched blastocysts in W-FBS than W-BSA (P<0.001). The objective of Experiment 2 was to compare development of porcine embryos collected prior to the transition from the maternal to zygotic genome in modified Whitten's medium supplemented with either 1.5 per cent fraction V BSA or 1.5 per cent essentially fatty acid-free BSA Embryos were flusshed as described above. No difference was detected for embryo development following 96 h of culture in fraction V or essentially fatty acid-free BSA (P>0.35). The objective of Experiment 3 was to compare the development of Meishan and Yorkshire embryos collected prior to the transition from the maternal to zygotic genome (one-, two- and early four-cell) in modified Whitten's medium +1.5per cent BSA, Embryos were collected, handled and cultured as described above. A higher percentage of one-cell Meishan embryos developed to the eight-cell and compact morula stages than one-cell Yorkshire embryos following 96 h of culture (P<0.10). More Yorkshire two-cell embryos developed to the eight-cell stage than Meishan two-cell embryos (P<0.10), However, no breed differences were detected for four-cell embryo development to any stage (P>0.15).