Thyroid Condition of Chickens and Development of Parasitic Nematodes

Abstract

Considerable recent literature has been devoted to effects of a thyroactive iodocasein (Protamone) and thiouracil on the growth, fattening, and feathering of broilers, vide Parker (1943), Irwin, Reineke, and Turner (1943), Turner, Irwin, and Reineke (1944), Kempster and Turner (1945), and Andrews and Schnetzler (1946). One immediate effect of these substances in the diet is exerted upon the activity of the thyroid and when the substances are fed at proper levels it is possible to produce mild hypothyrosis or mild hyperthyrosis in chickens. The above literature suggested that a further effect of these substances in the diets of chickens might be tested, namely, their effect on resistance to parasitism. It has been reported, Larsh (1947), that the daily addition of 3 mg of thyroid to the diets of mice resulted in a much higher percentage development of Hymenolepis than occurred in control animals. The present writer (1948a, in press) will report significantly superior growth of parasitized chicks with a mild hyperthyrosis when compared with growth of parasitized normal controls, and, when compared with growth of parasitized chicks with a mild hypothyrosis. Wheeler et al (1948) reported that 0.1 percent thiouracil in the diet of 2-week old chicks was not prejudidicial to the survival of birds artificially infected with cecal coccidiosis, while their data on 0.02 percent Protamone in the diet suggested that birds on such a diet were somewhat resistant to the same infection.