In conclusion I will cite the result of a series of experiments in applying the principles of physiological chemistry to poultry, and I may say that it took me twelve years to find the breed which would most readily lend itself to my purpose. I experimented with 250 varieties of hens before I found the one most amenable to my method of feeding and breeding.
While living at Needham, Massachusetts, I made a thorough test of my principles with the selected variety of hens. They were not only fed a ration properly balanced for protein, carbohydrates and fat, but I gave them a liberal supply of properly prepared mineral salts. I used three different mixtures of feed, made up in 100 pound lots, in which the proportion of albumen ranged from 13.50 to 18.00 pounds; of fat from 4.00 to 5.00 pounds; of carbohydrates from 41 to 44 pounds; and actual nutritive salts from 4.50 to 5.00 pounds. The respective ratios being: 1:4, 1:3.5 and 1:3
It is not necessary to enter into discussion of the details of the feeding method and the variation in the daily handling of the hens. The result of this experiment, however, was completely satisfactory, as the eggs produced by those hens not only contained a startling increase in the quantity of mineral salts, but their fertility was far greater than that of hens handled in the usual manner. The increase of fertility in itself is, it seems to me, the best proof of the soundness of my theoretical premises.
Some of the results of this experiment were published in the Reliable Poultry Journal in 1905, and Dr. Woods offered confirmatory evidence of the soundness of my conclusions two years later, after he had himself experimented along the same line.
I will cite just one fact revealed by that experiment, namely, that whereas 100 grams of dried egg yolk ordinarily contains only from 10 to 20 milligram of iron the eggs of those hens yielded from 30 to 80 milligrams. And all of the minerals were increased from 10 to 25 per cent or more.
The method of applying the principles of physiological chemistry to the enriching of the mineral content of our foodstuffs evolved by me is, with due recognition of the difference between the vegetable and animal kingdoms, equally applicable in the raising of all our foodstuffs with an augmented mineral content. I will adduce just one result of my work in the handling of small fruit: on the average, 100 grams of dried strawberries will yield 8.6 to 9.3 milligrams of iron, but strawberries raised by me yield from 30 to 40 milligrams per 100 grams.