102 FEEDS AND FEEDING, ABRIDGED 



the ration does not contain the dry matter called for, it shows that feeds 

 more concentrated in character than necessary have been used. In this 

 case some roughage or feeds higher in fiber may be substituted till the 

 dry-matter content is brought up to the standard. AVith this simple 

 check errors of any importance in the net-energy value of the ration 

 can be avoided. 



Necessity for modifying the Wolff-Lehmann standards. — It has 

 already been shown in this chapter that in several instances the original 

 Wolff-Lehmann standards do not set forth the actual requirements of 

 farm animals as revealed by the many experiments which have been 

 carried on since these standards were drawn up. We know, for 

 example, that the allowance of digestible crude protein prescribed is 

 higher than is needed by fattening animals, dairy cows, and work 

 horses. Yet, these standards are to-day more commonly employed in 

 this country, except perhaps with the dairy cow, than any other system 

 for formulating rations. Indeed, the authors have recently found 

 feeders, annually fattening hundreds and even thousands of animals, 

 who were balancing rations according to the original Wolff-Lehmann 

 standards by the addition of unnecessary amounts of high-priced 

 protein-rich concentrates. 



Modified Wolff-Lehmann standards. — With these facts in mind the 

 authors have attempted to combine in one standard what appear in 

 their judgment to be the best guides we have at present in the formu- 

 lation of rations for various classes of animals. To make the computa- 

 tions as easy as possible, the standards, which are given in detail in 

 Appendix Table V, are expressed simply in terms of total dry matter, 

 digestible crude protein, and total digestible nutrients. Realizing that 

 feeding standards are but approximations, in most cases minimum and 

 maximum figures are given for dry matter, digestible crude protein, 

 and total digestible nutrients. Since progressive feeders thruout the 

 country now appreciate the significance of the nutritive ratio of a 

 ration, the approximate upper and lower advisable limits of nutritive 

 ratios for the different classes have been stated. To correspond with 

 these standards, Appendix Table III contains a column showing the 

 total digestible nutrients furnished in 100 lbs. of each feed. Likewise, 

 so that one may see at a glance which feeds are high and which are low 

 in protein, compared with carbohydrates and fat, the nutritive ratio 

 for each feed has been computed and is given in the table. With these 

 aids it is hoped that the standards presented may be of real assistance 

 to students and feeders who desire to compute rations substantially in 

 accordance with the Wolff-Lehmann method, while recognizing the 

 results of the later investigations in animal feeding. 



