The present invention provides a method of improving disease management in an animal by administering an effective amount of .beta.-glucan composition to the animal. The .beta.-glucan composition comprises at least about 70% .beta.-(1,3/1,6)-D-glucan by dry weight and a biological activity of at least 20 .mu.g Bb released per mg of .beta.-(1,3/1,6)-D-glucan. The method may also result in beneficial secondary effects including an increase in growth efficiency of the animal; an increase in the survival rate of the animal; an increase in the colostrum quality of the animal; and any combination thereof. The .beta.-glucan composition may also be administered in combination with or prior to a vaccine, leading to an increase in antibody formation; the negative growth responses associated with administration of a vaccine may also be reduced. In the present method, the .beta.-glucan composition may be administered in combination with an animal feed.