Effect of progestins on serum hormones, semen production, and agonistic behavior in the gerenuk (Litocranius walleri walleri)

Linda M. Penfold, Linda Munson, Ed Plotka, Scott B. Citino

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The use of progestins to suppress endogenous testosterone production to reduce agonistic behavior and prevent semen production was studied in gerenuk. Five male gerenuk (20 months to 3 years of age), housed as a bachelor group, were treated with 3 monthly injections of medroxyprogesterone acetate (MPA; 2.5-20 mg/kg), followed by a melengestrol acetate implant (MGA; 0.3 g/kg) for 2 months. Blood samples collected monthly were assayed for serum testosterone and cortisol using enzyme-linked immunoassays. Quantitative behavioral data were collected for 30 min 3/week starting 1 month before treatment. Body weight, testes volume, and semen traits were measured before treatment, after MPA treatment, and after MGA treatment. Results showed lower (P < 0.05) mean serum testosterone concentrations after MPA (4.34 pg/ml) and MGA (5.02 pg/ml) treatment compared to pre-treatment values (65.9 pg/ml) in four of five gerenuk. The remaining sub-adult gerenuk had low testosterone initially (4.9 pg/ml) that did not decrease further with treatment (1.4 and 7.8 pg/ml for MPA and MGA, respectively). Mean serum cortisol concentrations decreased markedly after treatment with MPA (6.0 ± 3.7 ng/ml) and MGA (0.8 ± 0.3 ng/ml). Cortisol concentrations were regained rapidly post-treatment (42.8 ± 4.8 ng/ml) and were not significantly different from the pre-treatment value (60.6 ± 12.6 ng/ml; P > 0.05). The mean incidence of combined aggressive/dominant behaviors (horning, sparring, supplanting, threat) was not different before and after treatment. Body weight, total numbers of spermatozoa produced per ejaculate, percent motility, and percent normal spermatozoa declined maximally 8 months after treatment. Mean testes volume decreased (P < 0.05) after MGA treatment (10.53 cm3 vs. 11.96 cm3 pre-treatment). Elevated hepatic enzymes and bile acids were seen in three of five animals after progestin treatment and anorexia was noted in two males after MGA implant removal, however two of three males had elevated liver enzymes before progestin treatment began. Results show that reducing serum testosterone concentration does not seem to modify agonistic behavior in bachelor gerenuk groups.

Original languageEnglish (US)
Pages (from-to)245-257
Number of pages13
JournalZoo Biology
Volume26
Issue number4
DOIs
StatePublished - Jul 2007

Fingerprint

Agonistic Behavior
agonistic behavior
progestational hormones
Progestins
blood serum
Semen
testosterone
semen
hormones
Hormones
testes
enzymes
Serum
spermatozoa
melengestrol
medroxyprogesterone
liver
body weight
bile acids
immunoassays

Keywords

  • Antelope
  • Cortisol
  • MGA
  • MPA
  • Spermatozoa
  • Testosterone

ASJC Scopus subject areas

  • Animal Science and Zoology
  • veterinary(all)

Cite this

Effect of progestins on serum hormones, semen production, and agonistic behavior in the gerenuk (Litocranius walleri walleri). / Penfold, Linda M.; Munson, Linda; Plotka, Ed; Citino, Scott B.

In: Zoo Biology, Vol. 26, No. 4, 07.2007, p. 245-257.

Research output: Contribution to journalArticle

Penfold, Linda M. ; Munson, Linda ; Plotka, Ed ; Citino, Scott B. / Effect of progestins on serum hormones, semen production, and agonistic behavior in the gerenuk (Litocranius walleri walleri). In: Zoo Biology. 2007 ; Vol. 26, No. 4. pp. 245-257.
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