FEEDING STANDARDS CALCULATING RATIONS 113 



digestible nutrients contained in feeds. 3 These set forth the amounts of 

 digestible crude protein, carbohydrates, and fat required daily by the 

 different classes of farm animals. The Wolff standards were brought to 

 the attention of American farmers 10 years later and were further 

 introduced by Armsby's "Manual of Cattle Feeding," which appeared 

 in 1880. The value and importance of these standards were soon recog- 

 nized, and with their adoption came the first wide-spread effort toward 

 the rational feeding of farm animals. In 1896 the Wolff standards 

 were modified by Lehmann, as scientific trials had then thrown fur- 

 ther light on stock feeding. 



The numerous feeding experiments which have been carried on since 

 the Wolff-Lehmann standards were presented have given us much more 

 complete knowledge of the nutrients required by the various classes of 

 farm animals than was possessed by these pioneers in the field of animal 

 nutrition. Naturally, recent experiments show that these early stand- 

 ards are in many respects inaccurate. Taking these facts into con- 

 sideration, later scientists have drawn up other standards which are 

 presented later in this chapter. The Wolff-Lehmann standards are, how- 

 ever, briefly explained first on account of their historical and founda- 

 tional importance. 



156. The Wolfi-Lehmann feeding standards. The Wolff-Lehmann 

 standards are given in full in Appendix Table IV. From this the fol- 

 lowing examples are taken for purposes of study: 



Digestible nutrients required daily by farm animals per 1,000 Ibs. 



live weight 



The table shows that according to the Wolff-Lehmann standards a 

 1,000-lb. ox at rest, neither gaining nor losing in weight, requires for 

 1 day's maintenance 18 Ibs. of dry matter, containing the following 

 digestible nutrients: 0.7 Ib. crude protein, 8.0 Ibs. carbohydrates, and 

 0.1 Ib. fat, with a nutritive ratio of 1 :11,8. When the animal is growing, 

 fattening, giving milk, or doing external work, a larger quantity of 

 nutrients must be supplied than for maintenance, as the table shows. 



157. Wolff-Lehmann standards now out of date. Recent experiments 

 have conclusively shown that dairy cows, work horses, and fattening 

 cattle, sheep, and pigs all need considerably less crude protein than is 



s Mentzel and von Lengerke, Agricultural Calendar. 



