Reproductive and endocrine effects of active immunization against a XXXX conjugate in the heifer.

@entity251 @entity42 @entity73099 @entity1176 @entity291
Yearling heifers were actively immunized against 8 mg @entity73099 -ovalbumin in Non-Ulcerative Freund's Adjuvant, with or without the addition of Corynebacterium parvum (Groups A and B, respectively; N = 4 for each group). After the priming injection, Groups A and B were boosted twice at 4-monthly intervals. Control heifers (N = 9) were not injected. All treated animals except one gave a measurable antibody response, and all responding animals became anoestrous and displayed @entity42 after the first booster injection. There were no apparent differences between treatments, and so results for Groups A and B were pooled. At 25 weeks after the second booster 3 of the 7 responding, anoestrous heifers resumed cyclicity; one with two consecutive double ovulations, and one with one double ovulation. The 3rd heifer showed 4 corpora lutea, then became anoestrus again. The 4 remaining acyclic heifers, and the control heifers, were intensively blood sampled; the anoestrous heifers showed significantly higher mean LH and significantly lower mean FSH concentrations and higher LH pulse frequency than did the control animals. These heifers remained anoestrous for 11 months after the second booster, at which point they were injected with @entity1176 and PGF-2 alpha; only 1 heifer resumed ovarian cyclicity. These results indicate that it is possible to increase ovarian activity in @entity291 by active immunization against @entity251 , but that there is a high incidence of anoestrus.
