The Effect of Amprolium and of Payzone on the Functional State of the Thyroid in Growing Chickens

Abstract

Amprolium fed to growing chickens in a concentration of 125 p.p.m. in a commercial diet was accompanied by a small but significant decrease in thyroid activity compared with the results for untreated chickens, judged by serum PBI values. The epithelium : colloid relation was lowered. This was presumed to be a consequence of the antagonistic effect of amprolium on thiamine. Payzone feeding, 10 p.p.m. in commercial feed, caused a more pronounced retardation of thyroid activity, judged by the same criteria. A possible connection between the depressed thyroid function and the well-established improvement in weight gain and feed conversion in connection with payzone feeding is discussed.

Sammanfattning

Amprolium, 125 p.p.m. i kommersiellt foder, orsakade hos växande kycklingar en lindrig men signifikant (P< 0.001) sänkning i serum PB J. Histologiskt förelåg en sänkt epitel:kolloid-relation i sköldkörteln. Amproliums thiaminantagonistiska effekt förmodas vara orsaken till en minskning i sköldkörtelns aktivitet.

Payzone, 10 p.p.m. i samma basfoder, gav en kraftigare sänkning av serum-PBJ och epitel:kolloid-relation. Ett eventuellt samband mellan en sänkt sköldkörtelaktivitet och den väldokumenterade förbättringen i viktökning och foderutnyttjande i samband med payzoneutfodring diskuteras.