Vaccination against ergot alkaloids and the effect of endophyte-infected fescue seed-based diets on rabbits.
Three sequential experiments were conducted with rabbits to 1) determine the effect of endophyte-infected (E+) tall fescue seed on rabbit performance and examine the effect of anti-ergot alkaloid immunization on rabbit performance and protectiveness against fescue toxicosis, 2) compare immunogens designed to elicit systemic anti-ergot alkaloid antibodies, and 3) select a superior adjuvant. In Exp. 1, rabbits (n = 6/treatment) fed E+ fescue seed diets (20%, 340 ppb total ergot alkaloids) had reduced (P < .05) intake and weight gain compared with endophyte-free (E-) controls, whereas apparent diet digestibility was not different between E+ and E-. Rabbits immunized against ergot alkaloids (E+ vac) with lysergol conjugated to human serum albumin (Ly-HSA) had greater (P < .05) intake than E+ rabbits during the wk 1 of a 3-wk dietary challenge. In Exp. 2, rabbits (n = 4/treatment) were immunized with Ly-HSA, with H100-B (ergot alkaloid hapten, H100-different protein carrier, B conjugate), or combinations of both with alum as adjuvant. Greatest (P < .001) anti-ergot alkaloid antibody (Ab) titer developed in the group immunized with H100-B. In Exp. 3, rabbits (n = 4/treatment) were immunized with the immunogen H100-B in conjunction with six adjuvants. Freund's incomplete adjuvant (FIA) in combination with DEAE-dextran and FIA alone gave highest anti-ergot titers. In summary, rabbit weight gain and intake were reduced by feeding E+ fescue seed diets, immunization against ergot alkaloids provided temporary improvement in intake, and H100-B conjugate with FIA or FIA + DEAE-dextran as adjuvants elicited a superior anti-ergot immune response. We believe that rabbits may serve as a model animal for fescue toxicosis research.
Filipov
N M
NM
College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Thompson
F N
FN
Hill
N S
NS
Dawe
D L
DL
Stuedemann
J A
JA
Price
J C
JC
Smith
C K
CK
D000164:Acremonium; D000818:Animals; D000917:Antibody Formation; D003637:DEAE-Dextran; D004063:Digestion; D004435:Eating; D004876:Ergot Alkaloids / Q000276:immunology*; D004881:Ergotism / Q000517:prevention & control / Q000662:veterinary*; D005620:Freund's Adjuvant; D008297:Male; D006109:Poaceae / Q000382:microbiology*; D011817:Rabbits / Q000276:immunology; D011897:Random Allocation; D012639:Seeds / Q000382:microbiology*; D014611:Vaccination / Q000662:veterinary*; D015430:Weight Gain
D004876:Ergot Alkaloids; D005620:Freund's Adjuvant; D003637:DEAE-Dextran