1 1 6 POULTR r- CRAFT. 



155. Use of Feeding Standards. The practical value of a scientific 

 knowledge of feeding is that it enables a feeder to make up his ration " in the 

 rough" with absolute certainty that he has made no radical error none that 

 will not in the natural course of things soon be adjusted. A ration based on 

 (not necessarily adhering rigidly to) a correct standard is, in the hands of 

 a skillful feeder, practically self-adjusting. The calculations of values in 

 approved rations show that for ordinary purposes variations from the standard, 

 if made at all, need be but very slight ; for the differences between supply and 

 demand are not usually greater than will be controlled by the involuntary 

 adjustments of the natural checks and balances, viz. : the limited capacity of 

 the digestive organs ; the sense of taste, the instincts of hunger, the natural 

 cravings of a healthy appetite for the food articles best suited to meet present 

 requirements of the system ; the convertibility of the principal food elements ; 

 the tendency of the fowl's system to make the most of the food taken, expend- 

 ing some in egg production, using some for growth, storing some as fat, 

 squandering some as exuberant energy these are all constantly working to 

 bring about a proper balance of means and results, and the feeder's part must 

 be very badly done, indeed, if they fail. 



156. Extent of Actual Variations, from the Standards, in Complete 

 Rations. The system's demands for material for growth, or maintenance, 

 and strength, are, on the whole, very nearly constant for mature fowls, and 

 uniformly increasing for chicks. Fluctuations in food requirements are due 

 principally to variations in the amount of heat required to keep the body warm. 

 The standards of ratio and energy ascertained are for average conditions, such 

 as obtain generally in moderate weather, and in warm houses in cold weather. 

 Under such conditions the values of the grain ration are the values of the 

 whole ration, the small quantities of vegetables and meat eaten affecting it but 

 little. In summer the food actually consumed by a properly fed fowl would 

 have a narrower nutritive ratio than i : 6, and potential energy lower than 100. 

 The reduction would follow reduction in the quantity of the grain ration, and 

 large increase in the quantity of vegetables eaten, and would be governed 

 solely by the appetites of the fowls. In winter the heat of the body is 

 maintained partly by feeding more heating foods, but mostly by warm housing 

 and by giving the food and drink warm. The actual variation of a ration from 



narrow nutritive ratios are bulky foods, diluted either with water or with fiber. Low 

 potential energies are for hot-house conditions. Narrow nutritive ratios are extravagant. 

 Protein is the rarest and most costly food element. If one feeder uses a ration with a 

 nutritive ratio of i : 4, and another a ration with a nutritive ratio of i : 6, the general con- 

 ditions and the results in both cases being alike, the inevitable conclusion is that the wider 

 ratio furnished, at least, as much protein as the system needed, and that one-third of the 

 protein of the narrower ration was used for fuel. It would be no easy matter to find a 

 ration compounded with a view to cheapness and the best all round results, and proved 

 by long practical tests, which would, when computed, show a nutritive ratio anything 

 like as narrow as 1:4, or a potential energy lower than 90, except, possibly, in 

 extremely hot weather. 



