Influence of vitamin E and carcass feeding supplementation on fecal glucocorticoid and androgen metabolites in male black-footed ferrets (Mustela nigripes).
PLoS One 2020;
15:e0241085. [PMID:
33095820 PMCID:
PMC7584211 DOI:
10.1371/journal.pone.0241085]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 10/08/2020] [Indexed: 02/06/2023] Open
Abstract
In recent years, the ex situ population of the endangered black-footed ferret (Mustela nigripes; ferret) has experienced a decline in normal sperm morphology (from 50% to 20%), which may be linked to inbreeding depression and/or a dietary change. We examined the effects of adding carcass and vitamin E to the diet on stress and reproductive biomarkers in male ferrets (n = 42 males including 16 juveniles and 26 adults) housed at the U.S. Fish and Wildlife National Black-footed Ferret Conservation Center (Carr, CO, USA). Fecal samples (3x/week) were collected from November and December (pre-breeding season, no diet change), February through May (breeding season, diet change) and June (post-breeding season, diet change) and analyzed for fecal glucocorticoid metabolites (FGM) via a corticosterone enzyme immunoassay (EIA). A subset of samples from adult males (n = 15) were analyzed for fecal androgen metabolites (FAM) via a testosterone EIA. We first used a linear mixed effects model to identify the important fixed effects among meat treatment, vitamin E treatment, age class (juvenile or adult), and all possible interactions on each hormone. We then examined the important factor’s effects across seasons using the non-parametric Friedman test. We found that age did not influence (p = 0.33) FGMs; however there was a significant effect of meat treatment on FGM (p = 0.04) and an effect of vitamin E on FAMs (p<0.10). When fed carcass, FGMs declined (p<0.001) from pre- to the during the breeding season time period, but was similar (p>0.05) between during and post-breeding season periods. Males that were not fed carcass had higher (p<0.05) FGMs during the breeding season compared to pre- and post-breeding season and FGMs were lower (p<0.05) in the post-breeding season compared to pre-breeding season. Males fed with carcass had lower (p<0.001) FGM than males that were not fed carcass during both the pre-breeding and the breeding season but not during the post-breeding season (p>0.05). Males supplemented with vitamin E had higher (p<0.001) FAM than non-supplemented males during the breeding season only. For both groups, FAM was highest (p<0.05) during the breeding season. In conclusion, adding carcass to the diet can reduce glucocorticoid production and adding vitamin E can increase testosterone during the breeding season, which may influence reproductive success.
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