202 POULTRY FEEDS 



in the case of laying hens. It seems to be of less value for growing 

 chicks, as it contains little if any phosphate. Samples of crushed 

 oyster shells usually run over 95 per cent carbonate of lime. 

 Crushed shells are especially valuable when they can be fed fresh, 

 that is, gathered regularly from the beach, or after the oysters 

 or clams have been removed, and immediately crushed or ground. 



Sources of Phosphate. Composition (pounds in 100). 



Phosphoric acid, 

 Protein. P 2 O 5 . 



Granulated bone (dry) 25 24 



Green cut bone 19 to 34 23 to 25 



Phosphate rock 28 to 32 



Poultry grit is not valuable as a source of ash, as it usually 

 contains little if any lime, and very little phosphate, the main 

 component being silica. The function of grit is that of grinding. 



Other Sources of Mineral Matter. There are a great many 

 advertised sources of mineral matter for poultry feeding. Few of 

 the commercial forms, however, seem to supply the particular 

 kind of mineral in the best form. Raw phosphate rock gives fair 

 results, but the available mineral matter is small in comparison 

 with its bulk. There are certain advertised commercial feeds 

 which are guaranteed to contain a large quantity of ash. Some 

 of these, owing to their physical properties, are of little value, 

 and are not economical when compared with the results obtained 

 by the use of cheaper and better-known materials, such as bone 

 products. 



Ash in Grains. Wheat bran is a very efficient source of ash 

 and is fed quite extensively with this purpose in view. Consider- 

 ing only its value as a protein carrier, the cost of wheat bran is 

 relatively high, but considering its palatability and high ash con- 

 tent it can be highly recommended. It is desirable in the feeding 

 of baby chicks. There are other grains, such as barley and oats, 

 which contain enough ash to be worth considering. 



Double Function of Minerals. Experiments show that the ash 

 content in a ration bears a definite relation to the complete use 

 of other nutrients in it. Not only is the actual availability of the 

 mineral matter itself of value, but mineral compounds have a 

 very noticeable effect in increasing the digestibility of other 

 nutrients in the ration, especially protein. Minerals thus perform 

 a double function. 



