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 syst em for Chinese Meishan pig embryos. The objective of Experiment I was to co mpare in vitro development of Meishan embryos recovered at the four and eig ht-cell (EARLY) and compact morula and blastocyst (LATE) stages in a Whitte n'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 f rom reproductive tracts of Meishan females with Dulbecco's phosphate buffer ed saline (D-PBS), randomized to treatment and cultured in 50 mu l drops un der 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 o r four embryos per drop. Within treatment, no difference was detected betwe en one and four embryos per drop for development to any stage (P > 0.30). C ulture of EARLY embryos indicated that W-BSA supported greater development into compact morulae and blastocysts than W-FBS (P < 0.01), but neither tre atment permitted hatching from the zona pellucida. More LATE embryos develo ped into hatched blastocysts in W-FBS than W-BSA (P < 0.001). The objective of Experiment 2 was to compare development of procine embryos collected pr ior to the transition from the maternal to zygotic genome in modified Whitt en's medium supplemented with either 1.5 per cent fraction V BSA or 1.5 per cent essentially fatty acid-free BSA. Embryos were flushed as described ab ove. No difference was detected for embryo development following 96 h of cu lture in fraction V or essentially fatty acid-free BSA (P > 0.35). The obje ctive of Experiment 3 was to compare the development of Meishan and Yorkshi re embryos collected prior to the transition from the maternal to zygotic g enome (one-, two- and early four-cell) in modified Whitten's medium + 1.5 p er cent BSA. Embryos were collected, handled and cultured as described abov e. A higher percentage of one-cell Meishan embryos developed to the eight-c ell 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 e ight-cell storage than Meishan two-cell embryos (P < 0.10). However, no bre ed differences were detected for four-cell embryo development to any stage (P > 0.15).