Effects of dietary vitamin A content on antibody responses of feedlot calves inoculated intramuscularly with an inactivated bovine coronavirus vaccine.
OBJECTIVE
To investigate effects of low dietary vitamin A content on antibody responses in feedlot calves inoculated with an inactivated bovine coronavirus (BCoV) vaccine.


METHODS
40 feedlot calves.


METHODS
Calves were fed diets containing high (3,300 U/kg) or low (1,100 U/kg) amounts of vitamin A beginning on the day of arrival at a feedlot (day 0) and continuing daily until the end of the study (day 140). Serum retinol concentrations were evaluated in blood samples obtained throughout the study. Calves were inoculated IM with an inactivated BCoV vaccine on days 112 and 126. Blood samples obtained on days 112 and 140 were used for assessment of BCoV-specific serum IgG1, IgG2, IgM, and IgA titers via an ELISA.


RESULTS
The low vitamin A diet reduced serum retinol concentrations between days 112 and 140. After the BCoV inoculation and booster injections, predominantly serum IgG1 antibodies were induced in calves fed the high vitamin A diet; however, IgG1 titers were compromised at day 140 in calves fed the low vitamin A diet. Other isotype antibodies specific for BCoV were not affected by the low vitamin A diet.


CONCLUSIONS
Dietary vitamin A restriction increases marbling in feedlot cattle; however, its effect on antibody responses to vaccines is unknown. A low vitamin A diet compromised the serum IgG1 responses against inactivated BCoV vaccine, which suggested suppressed T-helper 2-associated antibody (IgG1) responses. Thus, low vitamin A diets may compromise the effectiveness of viral vaccines and render calves more susceptible to infectious disease.
Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691.
Junbae
J
Jee
Armando E
AE
Hoet
Marli P
MP
Azevedo
Anastasia N
AN
Vlasova
Steve C
SC
Loerch
Carrie L
CL
Pickworth
Juliette
J
Hanson
Linda J
LJ
Saif
D000818:Animals; D000914:Antibodies, Viral / Q000187:drug effects*; D002417:Cattle / Q000276:immunology*; D017938:Coronavirus, Bovine / Q000276:immunology*; D017931:DNA Primers / Q000235:genetics; D019587:Dietary Supplements; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D007074:Immunoglobulin G / Q000097:blood; D007273:Injections, Intramuscular / Q000662:veterinary; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018709:Statistics, Nonparametric; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology*; D014801:Vitamin A / Q000097:blood / Q000494:pharmacology*
D000914:Antibodies, Viral; D017931:DNA Primers; D007074:Immunoglobulin G; D015164:Vaccines, Inactivated; D014801:Vitamin A