Bovine rotavirus (BRV) is an important cause of
diarrhea in newborn calves. Local passive immunity is the most efficient protective strategy to control the disease.
IgY technology (the use of chicken egg yolk
immunoglobulins) is an economic and practical alternative to prevent BRV
diarrhea in dairy calves. The aim of this study was to evaluate the protection and
immunomodulation induced by the
oral administration of egg yolk enriched in BRV specific
IgY to experimentally BRV infected calves. All calves in groups Gp 1, 2 and 3 received control colostrum (CC; BRV virus neutralization Ab titer - VN=65,536; ELISA BRV
IgG(1)=16,384) prior to gut closure. After gut closure, calves received milk supplemented with 6% BRV-immune egg yolk [(Gp 1) VN=2048; ELISA
IgY Ab titer=4096] or non-immune control egg yolk [(Gp 2) VN<4; ELISA
IgY Ab titer<4] twice a day, for 14 days. Calves receiving CC only or colostrum deprived calves (CD) fed antibody (Ab) free milk served as controls (Gp 3 and 4, respectively). Calves were inoculated with 10(5.85)focus forming units (FFU) of virulent BRV IND at 2 days of age. Control calves (Gp 3 and 4) and calves fed control
IgY (Gp 2) were infected and developed severe
diarrhea. Around 80% calves in Gp 1 (
IgY 4096) were infected, but they showed 80% (4/5) protection against BRV
diarrhea. Bovine RV-specific
IgY Ab were detected in the feces of calves in Gp 1, indicating that avian
antibodies (Abs) remained intact after passage through the gastrointestinal tract. At post
infection day 21, the duodenum was the major site of BRV specific antibody secreting cells (ASC) in all experimental groups. Mucosal ASC responses of all isotypes were significantly higher in the
IgY treated groups, independently of the specificity of the treatment, indicating that egg yolk components modulated the immune response against BRV
infection at the mucosal level. These results indicate that supplementing newborn calves' diets for the first 14 days of life with egg yolk enriched in BRV-specific
IgY represents a promising strategy to prevent BRV
diarrhea. Moreover a strong active ASC immune response is induced in the intestinal mucosa following BRV
infection after the administration of egg yolk, regardless the specificity of the treatment.