Chicken egg yolk immunoglobulins (Yig) specific for bovine rotavirus (BRV) serotypes (G6, [P1]), (G10, [P11]) and bovine coronavirus (BCV) were prepared with egg yolks derived from hens immunized with each viral antigen. Anti-BRV Yig preparations were investigated in suckling mice model, in experimental neonatal calves challenge tests, and in a field condition with an epidemic outbreak of BRV. These results showed significant efficacies of anti-BRV Yig preparations (P<0.01). Anti-BCV Yig preparations were compared with anti-BCV cow colostrums antibody powder. It took about four times more colostral antibody than chicken egg yolk antibody to prevent mortality in neonatal calves (P<0.01). The data of these tests showed that oral administration of Yig had significant efficacies against BRV and BCV infections. These results raise the possibility of wide application of specific Yig against gastro-enteropathogenic diseases caused by other pathogens in animals and human.