Selenium toxicity in breeding ring-necked pheasants (Phasianus colchicus)

Area of Science:

• Avian Health
• Toxicology
• Animal Nutrition

Background:

• Selenium is an essential trace element, but high dietary levels can cause toxicity in poultry.
• Ring-necked pheasants are susceptible to environmental contaminants in their feed.

Purpose of the Study:

• To investigate the effects of high dietary selenium on breeding ring-necked pheasants.
• To identify clinical signs and pathological findings associated with selenium toxicosis in pheasants.
• To evaluate the impact of selenium toxicity on reproductive parameters and embryonic development.

Main Methods:

• A flock of ring-necked pheasants was fed a diet containing 9.3 ppm of selenium.
• Clinical signs, mortality, egg production, and hatchability were monitored.
• Necropsy and histopathology were performed on deceased birds.
• Selenium content of eggs was analyzed.

Main Results:

• Within 4 days, egg production decreased, aggression increased, and 12% of hens died.
• Histopathology revealed degenerative cardiomyopathy and hepatic necrosis.
• Egg production returned to normal within 10 days of removing the toxic feed.
• Eggs laid 8-14 days post-exposure showed 35% hatchability with 50% embryonic deformities.
• Eggs laid 21-28 days post-exposure had nearly normal hatchability (80%) and lower selenium levels (0.30 ppm).

Conclusions:

• High dietary selenium causes rapid toxicosis in pheasants with characteristic clinical and pathological signs.
• Selenium toxicity significantly impacts reproductive success, causing embryonic death and developmental abnormalities.
• Specific embryologic defects are indicative of selenium toxicity, and reproductive parameters recover after toxic feed removal.