Thyroxin induced moult in domestic hen.
Two identical experiments were carried out in domestic hens treated with a lower (0.2 mg/animal) or a higher (0.4 mg/animal) dose of thyroxin (T4), for 21 consecutive days. The low dose diminished egg production, but did not result in moulting while the higher dose stopped egg laying on the 16th day and caused the loss of contour feathers from the 14th day on. The new plumage was completely developed in this group on about the 42th day. The plasma progesterone concentration showed an increase in both thyroxin treated groups, but is was only continuous and significant in the fowls treated with 0.4 mg T4. In this group the peak value of progesterone was synchronous with the most intensive feather loss. In the other group the tendency for increased levels of progesterone was of shorter duration and not significant. Plasma oestrone levels were depressed by the treatment in both groups and increased significantly only in the moulted fowls after administration of T4 was stopped. This increase may be associated with feather growth and regeneration of the oviduct. Plasma 17-beta oestradiol and testosterone concentrations did not change in the T4 treated groups. Plasma corticosterone concentration increased continuously only in the moulting animals. The results suggest that on one hand thyroxin has a role in the endocrine regulation of moulting and, on the other, that a thyroxin-progesterone synergism is of significance in the process.
Szelényi
Z
Z
Laboratory of Geese Biochemistry, University of Agriculture, Gödöllö Hungary.
Péczely
P
P
D000818:Animals; D002645:Chickens / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D004958:Estradiol / Q000097:blood; D004970:Estrone / Q000097:blood; D005241:Feathers / Q000187:drug effects / Q000502:physiology*; D005260:Female; D010058:Oviposition / Q000187:drug effects; D012016:Reference Values; D013739:Testosterone / Q000097:blood; D013974:Thyroxine / Q000494:pharmacology*
D004970:Estrone; D013739:Testosterone; D004958:Estradiol; D013974:Thyroxine; D003345:Corticosterone