Immunization of heifers against gonadotropin-releasing hormone: antibody titers, ovarian function, body growth, and carcass characteristics.
To investigate the effects of active immunization of cyclic beef heifers with different doses of a human serum albumin-Cys-Gly-GnRH (HSA-GnRH) conjugate on antibody titers, ovarian function, body growth, and carcass characteristics, 32 heifers (BW = 477 +/- 7.1 kg; mean +/- SE) were assigned to one of four immunization treatments: .1 mg of HSA or .01, .1, or 1.0 mg of HSA-GnRH, respectively. All heifers received a primary (d 0) and booster (d 28) immunization using DEAE-dextran as adjuvant. The duration of the experiment was 158 d. Overall antibody titers against GnRH were greater (P < .05) for heifers immunized against GnRH (13 +/- 3.3, 22 +/- 3.8, and 19 +/- 2.8% binding at a plasma dilution of 1: 640 for Treatments 2 to 4, respectively) than for controls (1 +/- .1%). The numbers of heifers that became anestrous (plasma progesterone < .5 ng/mL for > 21 d) were 1/8, 8/8, 7/8, and 8/8, respectively. The interval from primary immunization to anestrus (40.7 +/- 6 d) and the duration of anestrus (78 +/- 7 d) were not affected by dose of HSA-GnRH conjugate. The number of ovulations detected was reduced (P < .05) in GnRH-immunized (4.6 +/- .64, 4.0 +/- .70, and 3.6 +/- .60 for Treatments 2 to 4, respectively) compared with control heifers (9.4 +/- .20). During induced anestrus, follicular growth was generally arrested (< 5 mm in diameter) and plasma estradiol decreased.(ABSTRACT TRUNCATED AT 250 WORDS)
Prendiville
D J
DJ
Teagasc, Grange Research Centre, Dunsany, Co. Meath, Dublin, Ireland.
Enright
W J
WJ
Crowe
M A
MA
Finnerty
M
M
Hynes
N
N
Roche
J F
JF
D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000032:analysis* / Q000276:immunology; D001823:Body Composition / Q000502:physiology*; D002417:Cattle / Q000254:growth & development* / Q000276:immunology / Q000502:physiology; D004958:Estradiol / Q000097:blood; D004971:Estrus / Q000502:physiology; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology*; D006080:Ovarian Follicle / Q000502:physiology; D010053:Ovary / Q000502:physiology*; D010060:Ovulation / Q000502:physiology; D011374:Progesterone / Q000097:blood; D012709:Serum Albumin / Q000378:metabolism / Q000494:pharmacology; D014611:Vaccination / Q000662:veterinary*
D000276:Adjuvants, Immunologic; D000906:Antibodies; D012709:Serum Albumin; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol