Effects of feeding high dosages of vitamin E to laying hens on thyroid hormone concentrations of hatching chicks

✍ Scribed by Engelmann, Daniela ;Flachowsky, Gerhard ;Halle, Ingrid ;Sallmann, Hans Peter

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 143 KB
• Volume: 290
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1034

✦ Synopsis

Abstract

Long‐term experimental feeding of 20,000 ppm α‐tocopheryl acetate to laying hens caused a significant (P < 0.05) decrease in hatching rates as compared to the control group, which was fed a diet containing 19 ppm α‐tocopherol. When the thyroid hormones in the developing chicks were checked on incubation days 16, 19, 21, and 22, the following results were ascertained: During the latter part of incubation, increases in plasma concentrations of thyroxine and triiodothyronine were observed. No significant differences in hormone concentrations (P > 0.05) between the control and the treatment group were observed during incubation days 16, 19, and 22. However, on the day of hatching (day 21 of incubation) significantly lower (P < 0.05) triiodothyronine concentrations in chick embryos of pipped eggs were found in the treatment group. Moreover, thyroxine concentrations in non‐pipped eggs and in hatched chicks were found to be significantly higher as compared to the control group. Given these results, one concludes that extremely high dosages of vitamin E may affect thyroid hormone concentrations of hatching chicks, and therefore, the chicks might be inhibited in pipping the egg shell. Hypothetically, the hepatic enzyme 5′‐monodeiodinase is involved in the mechanism of inhibition. J. Exp. Zool. 290:41–48, 2001. © 2001 Wiley‐Liss, Inc.