Demonstration of passive protection in neonatal calves against colibacillosis following immunization of pregnant heifers at 3 months of gestation.
Enterotoxigenic Escherichia coli is one of the primary etiologic agents for diarrhea in neonatal calves. Immunization of dams can provide passive protection in neonatal calves; antibodies transferred through colostrum block colonization of bacteria, thereby preventing disease. In this study, healthy pregnant heifers were vaccinated at approximately 3 months of gestation with either a polyvalent oil-adjuvanted vaccine containing inactivated coronavirus, rotavirus, E. coli K99 subunit antigen, and Clostridium perfringens b and e toxoid or normal saline as a placebo. Calves were allowed to nurse immediately after birth, were orally challenged with virulent heterologous enterotoxigenic E. coli at 1 day of age, and were observed for clinical signs of scours for 10 days. Signs of severe scours were noted in 75% of control calves and 28.6% of vaccinates, and the severity of scours was significantly higher (P = .0382) in the control group. The mortality rate was significantly higher (P = .0007) in the control group (80%) than in the vaccinate group (14%). These findings indicate that the vaccination of pregnant heifers at as early as 3 months of gestation (6 months before calving) provides passive protection in neonatal calves against colibacillosis.
Jayappa
Huchappa
H
Intervet/Schering-Plough Animal Health, Elkhorn, NE 68022, USA. huchappa.jayappa@sp.intervet.com
Davis
Randy
R
Dierks
Lindy
L
Sweeney
Diane
D
Wasmoen
Terry
T
D000818:Animals; D000831:Animals, Newborn; D000907:Antibodies, Bacterial / Q000032:analysis; D000942:Antigens, Bacterial / Q000276:immunology; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology* / Q000517:prevention & control*; D054307:Enterotoxigenic Escherichia coli / Q000276:immunology*; D004927:Escherichia coli Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D005260:Female; D005865:Gestational Age; D007116:Immunization, Passive / Q000379:methods / Q000662:veterinary*; D011247:Pregnancy; D011897:Random Allocation
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial