Bovine morulae (day 6: n=257) were obtained to evaluate the [effect of immunoglobulins (Ig) on early bovine embryo development in vitro. Fifty-four cows superovulations were conducted in 36 cows with follicle stimulating hormone. Embryos were collected by non-surgical procedures and morphologically evaluated and randomly assigned to culture. Embryos were cultured in Ham's F-10 containing 10% (6.4 mg/ml) steer serum (SS), 1% (.64 mg/ml) bovine gamma . globulins (GG), 1% (.64 mg/ml) bovine IgG, 1% (.64 mg/ml) bovine 1gM, 10% SS plus 1% GG, 10% SS plus 1% 1gG, or 10% SS plus 1% 1gM. Embryos were cultured to the hatched blastocyst stage or degeneration and evaluated at 12 h intervals.