Pituitary feeding and egg production in the domestic fowl

Abstract

Clark 1 found, in 1915, that the egg production of chickens (White Leghorns) was markedly increased by feeding dried pituitary (anterior lobe) in amounts representing 20 mg. of the fresh gland to each hen per day. The effect became evident four days after the feeding began and lasted for several days after the last dosage. The experiments were carried out in May, when the laying curve was on the decline, nevertheless the egg production reached 100 per cent. for the experimental pen (35 hens on two consecutive days laid 35 eggs) or double what it had been before the feeding was begun. He lays emphasis on the fact that the glandular material he used was taken from young, growing animals—calves and lambs.

I have repeated the experiments of Clark when the egg production was low and declining—in June and July, 1917, when low and increasing—December and January, 1917-18, when high (about the maximum)—April, 1918—and again in March and April, 1919, and have been unable to observe any increase from pituitary feeding. The adult gland (ox) was used and also that of the growing animal (calf), and the method of preparation adopted by Clark was followed as closely as possible. To begin with, the amount given by him was administered, viz, the equivalent of about 20 mg. of fresh pituitary substance (anterior lobe), to each hen individually, in a gelatine capsule, and when no result was obtained tihe dose was doubled and later trebled. In no case was any distinct effect produced, the egg-laying curves running practically parallel with those of the control pens. Single Comb White Leghorns were employed.