The successful transfer of passive immunity via colostrum to the newborn dairy calf continues to be a significant challenge. In spite of years of research and implementation of systems for colostrum management, over 30% of calves exhibit failure of passive transfer (FPT) (NAHMS, 1993). A discussion of the challenges of transfer and development of immunity in the calf represented a significant portion of the program of a recent ADSA Discover Conference held in 2008 entitled: “Biology of the Calf”.

Maternal HT during late gestation decreased calf birth weight and weaning weight and compromised the passive IgG transfer, regardless of colostrum source. Feeding colostrum from HT cows during the dry period did not affect AEA or growth performance during the preweaning period, but seemed to impair humoral im- mune response during the first month of life.

Although ensuring that calves have APT is the most significant management factor to ensure the health of neonatal calves on calf ranches, colostrum supplementation during the first 2 wk of life in calves was effective in reducing diarrheal disease and the use of antimicrobials. The ADG up to 4 wk of age in colostrum-supplemented calves was significantly greater compared with that in control calves, likely because of a combination of greater energy intake through the liquid feed, increased grain intake, and fewer days with diarrhea.