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Immunocontraception of male and female giraffes using the GnRH vaccine Improvac®
Author(s) -
Schwarzenberger Franz,
Krawinkel Pia,
Jeserschek SophiaMaria,
Schauerte Nicole,
Geiger Christina,
Balfanz Folko,
KnaufWitzens Tobias,
Sicks Florian,
Martinez Nevado Eva,
Anfray Gwendoline,
Hein Anna,
KaandorpHuber Christine,
Marcordes Sandra,
Venshøj Betina
Publication year - 2022
Publication title -
zoo biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.5
H-Index - 54
eISSN - 1098-2361
pISSN - 0733-3188
DOI - 10.1002/zoo.21651
Subject(s) - biology , endocrine system , physiology , feces , reproduction , corpus luteum , immunization , hormone , medicine , endocrinology , immunology , immune system , ecology
The aim of this study was to develop protocols for contraception in both sexes of giraffes ( Giraffa camelopardalis ) by using the GnRH vaccine Improvac®. We evaluated the success of immunization by analyzing fecal reproductive hormone metabolites in female ( n = 20) and male ( n = 9) giraffes. Endocrine analysis provided the basis for the successful immunization protocol, as well as for assessing long‐term effects. Reliable reduction of fecal steroid metabolites to baseline levels in female giraffes was achieved with three, and in males with four or five injections at 4‐week intervals. Effective booster injections were administered at 2‐month intervals in the first year of treatment and at three to 4‐month intervals in the following years. In addition to endocrine analysis, we determined vaccination efficacy in bulls by assessing testicular atrophy. Long‐term (>2 years) use in females was often accompanied by prolonged periods of persistent corpus luteum activity, although normal cycles were not observed. Problems might occur with reversibility, because in a few males and females, even after more than 2 years since treatment had been stopped, fecal hormone metabolites have not returned to pretreatment levels. The results are somewhat ambiguous, as reproduction can be suppressed by use of Improvac®, but the question of reversibility remains unsolved.