318 POULTRY PRODUCTION 



Physiological Efficiency of the Laying Hen. — In tlie amount 

 of edible fooil solids manufactured as compared with the 

 weiglit of the dry matter in her body the hen leads all farm 

 animals. As shown in Table XXXVI, a three and a half 

 pound Leghorn hen, laying two hundred eggs in a year, 

 produces hve and three-quarter pounds of edihle-f(^od solids, 

 or 3.8 times the amount of dry matter in her body. The 

 cow is the only farm animal which is at all comparable with 

 the hen in this particular. 



A Jersey cow weighing 1000 pounds, giving 7000 pounds 

 of milk containing 14 per cent solids, would rank as high, 

 if not higher, among dairy cattle than the hen mentioned 

 would raidv among high-producing hens. Such a cow would 

 produce 2.9 times her own dry-matter weight in solid food. 



Table XXXVI. — A T'omparison of the Hen and the Dairy Cow 

 IN Physiological Efficiency. 



Dairy cow, Hen. 



pounds. pounds. 



Gross weight 1000 3.5 



Dry-matler weight .340 1.5 



Edible soHds produced in one 3'ear 980 5 75 

 Proportion of dry matter of the body 



to edible solids pioduced lto2.SS llo.3.8.3 



Digestibility of Feeds. — The mere chemical composition of 

 a fecdstufT is of little value in poultry feeding unless it is 

 known how much of each nutrient is digestible and avail- 

 able for the fowls. It is not enough, for instance, to know 

 that oats contain ll.S per cent protein, 59.7 per cent carbo- 

 hydrates and .5 per cent fat. In order to have an intelli- 

 gent basis for feeding, it must also be known what proportions 

 of these nutrients are digestible for poultry. 



Ash is usually absorbed by the intestine without change 

 in composition, and cannot be said to undergo digestion in 

 the ordinary sense of the term. Insolul>!e ash compounds 

 may be rendered soluble by the hydrochloric acid of the 

 glandular stomach. 



Ordinarily no nutrient is comiilctcly digested and assimi- 

 lated by fowls. The inidigcstcd ])ortion passes through the 

 body without change, and has manurial value only. That 



