FUNDAMENTALS OF FEEDING 225 



course, more noticeable with growing than with full-grown 

 animals. ' ' 



As the egg-producing capacity of fowls is improved there 

 is increased demand for the mineral elements, and the suc- 

 cessful poultryman will see that there is no deficiency in 

 this respect in the ration. The mineral matter in the body of 

 the fowl is largely phosphate of lime, while the egg shell is 

 almost entirely carbonate of lime. 



Ground bone is the most available form in which to fur- 

 nish the mineral matter for body growth. Eapidly growing 

 young chickens require much mineral matter in the form 

 of lime phosphates which are found in bone. It is different 

 in the case of the laying hen. The shell of the egg is almost 

 all carbonate of lime and this is found in its most available 

 form in oyster shells. 



But little is known of the effects of the specific mineral 

 elements, phosphorus, iron and sulphur, on production or 

 growth. It will be a distinct advance in the practice of 

 feeding when more definite knowledge has been gained of 

 the part played in the economy of feeding by these dif- 

 ferent mineral compounds of ash. 



Protein is the most valuable part of the food, because, 

 though it is found in all poultry foods, it is not found in 

 the cheaper foods in sufficient amount for the needs of the 

 fowl, especially the laying fowl. Foods containing a high 

 percentage of protein are usually the most expensive. Pro- 

 tein makes the lean meat and the muscle and a large per- 

 centage of the contents of the egg. The white of the egg, 

 lean meat, gluten of the flour, and milk casein are practi- 

 cally all protein. 



The value of the food must be determined largely by the 

 amount of protein which it contains, and high prices should 

 not be paid for food of any kind unless it has a guaranteed 

 analysis of high protein content. Generally speaking, foods 



