The ungulates possess an epteriochondrial placenta, which separates the maternal and foetal blood systems and thus reduces the permeability of the placenta to small molecules. Thus, in these species, the colostral imminoglobulins are the main source of protection factors which aid survival in the first days of life. This review deals with several aspects of passive immunity in ungulate neonates: the type and the origin of colostral immunoglobulins and factors which influence their production in the mother and their absorption form the gastrointestinal tract of the neonate.Recommendations for farmes to enhance natural postnatal immunity and recent technological advances in the production of immunoglobulin preparations are discussed.

The mortality and morbidity of young production animals causes serious economic losses. This concerns both the developing countries as well as countries leading in modern animal production. The early postnatal period and weaning period are the most risky phases during the entire production process. KEY WORKS: young animals, mortalityThe mortality of young animals has an important effect on farm economy. Dardillat and Vallet (1984) have estimated the mortality of calves in France at about 10% during the first month post-partum. A quick calculation allows the losses linked to this figure to be calculated. In France, about 4 millions dairy calves and 3.7 millions beef calves are born each year. A reasonable estimation of the cost of each type of calf is 200 US $ for the former and 500 US $ for the latter (Fougeres market, 1998). By using the above mentioned mortality rate of 10%, the overall loss is estimeted as 265 millions US $. The death of a calf is often the result of human negligence, perhaps of inattention can lasting only a few minutes. This cost of 200 US $ represent the equivalent of the revenue of 600L of milk, and therefore near 10% of the annual production of a good dairy cow. This quantity of milk is important and could only compensate the loss of a calf at the expense of considerable effort and not-negligible supplementary costs. For the beef calf, this comparison is not necessary because beef cow production is judged by the number of calves produced. When a calf dies, the farmer has to maintain the cow for a year during which it is unproductive. This loss can be considerable.