338 FEEDS AND FEEDING 



and poultry, has already been shown in Chapters V and VI. It has 

 there been pointed out that she returns about 6 times as much edible 

 solids in her milk for each 100 Ibs. of digestible nutrients in the food 

 consumed as the steer or sheep yields in its carcass. (131-2) Further- 

 more, a cow yielding only 8,000 Ibs. of milk of average composition pro- 

 duces annually in her milk 56 per ct. more protein, 30 per ct. more non- 

 nitrogenous nutrients (fat and sugar) and 19 per ct. more mineral 

 matter than in the entire body of a 2-year-old fat steer weighing 1,200 

 Ibs. (147) 



The economy of food production is even more striking in the case of 

 high-producing cows. Eckles 1 reports that a Holstein cow at the Mis- 

 souri Station, which yielded 18,405 Ibs. of milk in a year, produced dur- 

 ing this time 552 Ibs. of protein, 618 Ibs. of butter fat, 920 Ibs. of milk 

 sugar, and 128 Ibs. of mineral matter, a total of 2,218 Ibs. of edible dry 

 matter of the highest value for human food. The entire body of a 1,250- 

 Ib. steer, fed at the same station and analyzed by Trowbridge, contained 

 only 172 Ibs. protein, 333 Ibs. fat, and 43 Ibs. mineral matter, a total of 

 but 548 Ibs. This included not only the edible dry lean meat and fat, 

 but also all other parts of the body hoofs, hair, hide, horns, bones, 

 tendons, and all internal organs. During the year the cow thus pro- 

 duced enough protein to build the bodies of 3 such steers, fat sufficient 

 for nearly 2, and mineral matter enough for 3, besides 920 Ibs. of milk 

 sugar, which is as nutritious as the same weight of cane sugar. 



Concerning these data Eckles writes: " These figures show the re- 

 markable efficiency of the cow as a producer of human food. It is be- 

 cause of this economical use of food that the dairy cow and not the steer 

 is kept on high-priced land. When land is cheap and feed abundant, 

 the meat-producing animals predominate, but when the land becomes 

 higher in value and feed expensive, the farmer turns to the dairy cow. ' ' 

 (200) 



In extensive trials covering 9 years Haecker of the Minnesota Station 2 

 studied the use of feed by cows averaging 910 Ibs. in weight and yield- 

 ing about 24 Ibs. of milk daily containing approximately 1 Ib. of butter 

 fat. On the average these cows required about 46.5 per ct. of the digesti- 

 ble nutrients in their feed for the maintenance of their bodies, and re- 

 turned 29.1 per ct. in the milk they produced. The remainder, 24.4 per 

 ct., was used up in the work of producing the milk. 



Basing similar computations on the gross energy of the feed consumed 

 (not the energy in the digested nutrients) and the energy in the milk 

 produced, it will be found that cows producing about 1 Ib. of butter 

 fat a day will return in their milk about 17 per ct. of the gross energy 

 in their feed. From whatever standpoint we study the matter, it is 

 shown that the dairy cow is unsurpassed in the efficiency with which 

 she converts roughage and concentrates into human food. 



1 Hoard's Dairyman, 41, 1910, p. 122. 

 3 Minn. Bui. 140. 



