Influence of short-term dexamethasone-induced stress on behavioral, physiological and reproductive performance of growing rabbit bucks.

Abstract

The purpose of this study was to investigate how growing rabbit bucks responded to stress induced by dexamethasone (DEX). Sixteen New Zealand White male rabbits (4-5 months old, 2.75 ± 0.07 kg) were randomly assigned to four groups. After a one-week preliminary period under the same management, three groups received intramuscular DEX injections for seven consecutive days at doses of 1, 2, and 3 mg/kg body weight (D01, D02, and D03, respectively), while the control group (D00) received saline. Reproductive, behavioral, and physiological stress indicators were assessed throughout the preliminary, treatment, and two- weeks recovery periods. DEX administration induced dose-dependent adverse effects. Significant reductions in body weight gain, testosterone levels, sexual behavior, and semen quality were observed. High doses of DEX produced a great increase in anxiety-related responses in the open field test, and also in the novel object recognition test, they produced a great decrease in chin marking frequencies during the third 5 min habituation, discrimination ratio (RI), and primary object recognition response (PORR); and altered discrimination ratio for both RI and PORR. Physiological stress markers, including triiodothyronine levels, rectal temperature, and pulse rate, increased significantly, particularly in higher dose groups. The neutrophil-to-lymphocyte ratio also rose in a dose-dependent manner, with only partial recovery post-treatment. In conclusion, high-dose DEX administration in growing rabbit bucks negatively affects semen quality, behavior, growth, and hormonal balance, even over short durations. Therefore, glucocorticoids must be used carefully when breeding animals, particularly during sensitive developmental stages.