40 



MAINTENANCE RATIONS OF FARM ANIMALS. 



perature in these experiments, however, Wolff 1 when formulating 

 his well-known feeding standards increased this amount to 9.1 pounds 

 digestible organic matter, equivalent to about 15.9 therms of meta- 

 bolizable energy. Numerous subsequent experiments, 2 however, 

 showed quite clearly that this estimate was considerably too high 

 but without affording a sufficient basis for its correction, and it is 

 only since 1898 that really satisfactory data have been secured. 



One general method of experimentation has already been illus- 

 trated in the computation on pages 34-35 of the maintenance require- 

 ment of a steer. In brief, it consists of comparing the losses of body 

 energy by the animal when fed two different amounts of the same 

 feed or combination of feeds, each being less than the maintenance 

 ration, and computing from the difference the amount of energy 

 required for simple maintenance. 



Investigations by Arrusby and Fries 3 include eight trials with three different 

 animals substantially upon this plan. In the later experiments of the series 

 a correction was made for differences in live weight in the different periods 

 of each experiment and for differences in the amount of time spent standing 

 and lying, the results being computed to 12 hours standing. The results here 

 given for the earlier experiments have been corrected in the same manner 

 and therefore differ somewhat from those originally reported. The follow- 

 ing tabulation of the results shows also, for comparison, the percentage avail- 

 ability of the metabolizable energy of the feed and likewise the maintenance 

 ration expressed in terms of metabolizable energy. The results in every case 

 have been computed to a uniform live weight in proportion to the two-thirds 

 power of the weight. It is to be noted that the experiments are upon coarse 

 fodder (clover and timothy hay) exclusively, and that the animals were not fat. 



Maintenance requirements and rations of steers — Armsby and Fries. 



Years. 



Animal. 



Available energy 

 for maintenance. 



Percent- 

 age 

 availa- 

 bility of 

 metabo- 

 lizable 

 energy. 



Metabolizable en- 

 ergy for main- 

 tenance. 



Feed. 



Per 500 

 kilograms 

 live 

 weight. 



Per 1,000 

 pounds 



live 

 weight. 



Per 500 

 kilograms 

 live 

 weight. 



Per 1,000 

 pounds 



live 

 weight. 



1903 



1904 



1905 



1906 



1906 



1907 



1907 



Average of all 



Average, omitting 

 1904. 



Average, 1905-1907 



i 



A 

 B 

 A 

 B 

 A 

 B 



Therms. 

 6. 483 

 7.812 

 6. 649 

 7.532 

 6. 077 

 6. 806 

 5.186 

 6. 931 



Therms. 

 6. 076 

 7.321 

 6.231 

 7.058 

 5.695 

 6.378 

 4. 860 

 6. 496 



Per cent. 

 50.88 

 80. 24 

 60.51 

 55.21 

 [57.05] 

 [56. 50] 

 57.05 

 56. 50 



Therms. 

 12.742 



9.736 

 10.988 

 13. 642 

 10. 652 

 12. 046 



9.090 

 12. 267 



Therms. 

 11.942 



9.124 

 10. 297 

 12. 784 



9.982 

 11.288 



8. 519 

 11. 497 



Clover hay. 

 Do. 



Timothy hay. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 



6. 685 

 6.523 



6. 531 



6. 2G4 

 6.113 



6.121 



59.24 

 56.24 



57.14 



11.395 

 11. 632 



11. 447 



10. 679 

 10. 901 



10.728 



1 Landwirtschaftliche Fiittorun^slchre, 2d ed., 1877, pp. 132 and 196. 



2 The Maintenance Ration of Cattle, Pennsylvania Experiment Station Bulletin 42, 

 pp. 12-21. 



8 Bureau of Animal Industry, Bulletins 74, 101, and 128. The results reported in 

 Bulletin No. 51 can not be computed directly in this way because the ration included a; 

 small fixed amount of linseed meal. 



