~ tty oe 
New York AGRICULTURAL EXPERIMENT STATION. 77 
nearly all at the same time. By the first week in October only a 
few of the fat-fed hens had begun to molt while several in the other 
iot were in new plumage. 
In reporting the experiment it was suggested that a highly nitrog- 
enous ration be fed at the approach of molting time. 
THE SOURCE OF MATERIAL FOR THE EGG SHELL. 
It had generally been thought unnecessary to consider the mineral 
constituents of foods when feeding most animals, but it became an 
important matter when feeding numbers of laying hens in confine- 
ment, for considerably more than one-third of the total dry matter 
of an egg is mineral, chiefly lime. 
For some time there had been active discussion among poultry- 
men over the question whether oyster shell could be of any use to 
the hen as a source of material for the egg shell. It was becoming 
more generally known that ordinary foods, principally grain, sup- 
ply an insufficient amount of lime. Some experienced men whose 
opinions deservedly carried much weight, strongly maintained that 
the carbonate was too insoluble to be an available source of lime, 
and sought to supply the known deficiency by feeding large amounts 
of clover and similar foods comparatively rich in this constituent, 
although a ration carrying enough lime in such bulky foods would 
be otherwise inefficient. 
Several limited feeding trials made in connection with the study 
of this subject gave suggestive but inconclusive results. In 1891 
another experiment!® was made after some preliminary work such 
as partial analyses of the soluble contents of a number of crops, 
gizzards and intestines and of large oviducts, inactive, and taken 
at time of active shell formation from hens that had been fed 
oyster shell and from others that had not. These examinations 
gave no conclusive information; but considerable free acid was 
always found in portions of the digestive tract, enough to dissolve 
carbonate of lime. After a pen of hens had been confined for ten 
days’in a clean pen where nothing edible could be obtained except 
the intended food more detailed account was kept, for a period of 
ten days following, of the amount and composition of both food 
and product. Again after the close confinement for twenty-three 
days detailed account was continued for a period of twelve days 
following. Similar work with ducks was discontinued as they did 
not lay well enough to supply conclusive results. 
* Bul. 38; also in Rpt. 10:182-189 (18091). 
