66 FEEDS AND FEEDING, ABRIDGED 



have to stop rebuilding, tho having many perfect bricks left, because 

 none have the green end required for the pattern. 



Some proteins, such as the principal ones of wheat, furnish as much 

 as 40 per ct. of a single amino acid, which forms only 14 per ct. of the 

 animal proteins. "When such protein alone is given to growing ani- 

 mals, obviously a considerable part will be wasted and growth will be 

 checked. Proteins which entirely lack some of the necessary amino 

 acids will produce no growth whatever when fed alone. However, if 

 the necessary amino acids are added to the ration, the animal will be 

 able to continue growth. 



The various incomplete or unbalanced proteins do not all lack the 

 same amino acids. Hence, when two incomplete proteins are com- 

 bined one may supplement the deficiencies of the other and better 

 growth be made than on either alone. For example, experiments 

 with pigs - have shown that when corn alone was fed but 23 per ct. of 

 the protein was built into body protein, and when only linseed meal 

 was fed, but 17 per ct. When a mixture of three-fourths corn and 

 one-fourth linseed meal was given, the results were considerably better 

 than on either feed alone, 37 per ct. of the protein being used in 

 growth. This indicates that corn and linseed meal are not deficient 

 in the same amino acids, and that when combined one feed helps to 

 correct the deficiencies of the other. It is doubtless partly due to this 

 fact that better results are often secured in practice when a variety of 

 feeds is used than when but one or two are fed. The greater variety 

 lessens the danger of a deficiency in the proteins furnished. 



The various chapters of Part III show the combinations of feeds 

 which have been most successfully used for growing animals of the 

 various classes. 



Mineral matter required for growth. — It has already been shown 

 that the young animal, growing rapidly in skeleton and body tissues, 

 needs a liberal supply of mineral matter, especially calcium (lime) 

 and phosphorus. Enough must be furnished not only to provide for 

 the growth of the muscles, bones, etc., but to replace the small daily 

 loss from the body. 



The injurious effects of a lack of mineral matter are shown in a 

 trial at the Wisconsin Station ^ in which one lot of growing pigs was 

 fed wheat bran from which most of the phosphorus had been removed 

 by washing, together with wheat gluten and rice, both of which feeds 

 are extremely poor in mineral matter. Other lots were fed the same 

 ration plus ground rock phosphate or bone ash, which supplied ample 

 calcium and phosphorus. For a considerable period all the pigs 



2McCollum, Jour. Biol. Chem., 19, 1914, p. .323; information to the authors. 

 3 Hart, McCollum and Fuller, Wis. Res. Bui. 1. 



