[Frontiers in Bioscience 2, d471-481, September 15, 1997]|
THE COLOSTRUM-DEPRIVED, ARTIFICIALLY-REARED, NEONATAL PIG AS A MODEL ANIMAL FOR STUDYING ROTAVIRUS GASTROENTERITIS
Department of Animal Science, North Carolina State University, Raleigh, NC 27695-7626 and Center for Gastrointestinal Biology and Diseases, Chapel Hill and Raleigh, NC
Received 9/5/97 Accepted 9/10/97
4. IMMUNOLOGICAL CONSIDERATIONS OF NEWBORN PIGS
The pig is born void of circulating immunoglobulins and belongs to a group of neonatal mammals which acquire passive immunity from their dam exclusively postpartum. Furthermore, the intestinal absorption during its early postnatal period is qualitatively non-selective, henceforth, the neonatal pig is able to absorb a wide variety of unaltered or undigested macromolecules (35, 36). The cessation of this non-selective absorption process (closure) seems to be dependent on the feeding regimen rather than on the age of the pig (36). Thus, closure in nursing pigs occurs between 24 and 36 hours of age, while pigs that were starved from the time of birth continued absorbing large molecules for at least 86 hours (37).
Extensive research (36 - 43) has demonstrated the importance of sow's colostral immunoglobulins in conferring the newborn pig with passive immunity to infectious disease that is essential to pig survival. Henceforth, colostrum-free pigs have been shown to be very susceptible to microbial pathogens, particularly to enterotoxigenic Escherichia coli. Early attempts to artificially rear newborn pigs showed that colostrum-deprived pigs died very shortly after birth because of severe diarrhea and dehydration (44, 45).