Physiology and Reproduction

Testosterone profiles and semen characteristics were determined using yearling and adult captive wild-strain Mallard (Anas platyrhynchos) drakes. Wild-strain Mallard hens were artificially inseminated by modifying a technique developed for domesticated poultry. In both adult and yearling drakes, there was a change in the concentration of circulating plasma testosterone during the reproductive season. Testosterone concentrations increased from basal levels in March, peaked in April, and decreased to basal levels in May. The decrease in testosterone concentration to basal level was 2 wk earlier in yearlings than in adults (P < 0.05). The decrease in testosterone concentration was associated with the onset of postnuptial molt. Semen volume (0.04 to 0.08 mL) and semen concentration (∼1.32 × 109 spermatozoa per milliliter) were not different between adult and yearling drakes (P > 0.05). Overall mean fertility for yearling and adult drakes obtained with artificial insemination was 70.4%. These results suggest that artificial insemination may be used successfully in the propagation of captive wild-strain Mallard ducks. (