In previous papers by the authors(l,2) it was shown that the vitamin A content of the colostrum of cows varied within wide limits and that the wide range was not due to any differences in dietary, breed or date of calving in animals kept under the same conditions of management. It was also established that calves born of cows whose colostrum possessed a vitamin A content of less than 250 blue units (Moore's) per 100 ml. were more liable to infections such as white scour, navel-ill and joint-ill than were calves from cows whose colostrum had a vitamin A content of more than 250 blue units per 100 ml.