CALCULATION OF RATIONS 



75 



By reference to Table III in the Appendix it will be found that 

 the feeds given in the preceding example" contain the following 

 amounts of digestible protein and energy values : 



Ration Expressed in Protein and Energy Values 



The agreement between the standard and the digestible true 

 protein of the calculated ration is as close as can be desired in this 

 case.- No importance can be attached to the slight excess of 0.15 

 pound in the digestible protein, while there is an excess of energy 

 value of about 3 therms. A ration like the one given evidently 

 furnishes ample nutrients and will be found efficient in feeding 

 dairy cows with a medium milk flow, say 20 pounds a day. 



Comparison of Standards. — The Wolff-Lehmann and the 

 Armsby standards are recommended for use in calculating rations by 

 different authorities, and both will be found valuable for this purpose. 

 Either set of standards has the advantage over the other in certain 

 points, and students should become familiar with both, so as to be 

 able to apply in each case the particular method of calculation that 

 may best serve the purpose in view. We have seen that the Armsby 

 standards are, in the main, derived from the investigational work 

 done during the last few decades by German and American 

 scientists, largely Kellner and Armsby, both working mainly with 

 mature fattening steers. Only a small amount of research work 

 relative to the application of the system of energy values to the 

 feeding of other farm animals has been done; in case of some 

 animals, like pigs, and poultry, such work is entirely lacking, so 

 that the standards based on energy values, proposed for all animals 

 except fattening cattle, do not rest on a very secure basis. 



The Wolff-Lehmann standards, on the other hand, do not take 

 cognizance of the varying value of digestible matter in different 

 feeding stuffs due to the losses of energy in the processes of digestion 



