FEEDING STANDARDS— CALCULATING RATIONS 95 



Discussion of the net energy systems. — Determining the net energy 

 values of feeds is an important advance in our knowledge of their val- 

 ues for productive purposes. Unfortunately, owing to the immense 

 amount of labor required for each determination, data of this kind can 

 be secured but slowly. In his years of study Kellner determined the 

 starch values for only about a dozen feeds and in 14 years Armsby has 

 been able to study only 10 feeds, several determinations of course hav- 

 ing been made upon each. While the results for these few feeds are 

 helpful in estimating the probable net energy values of other feeds 

 not yet tested, such computed results are more or less rough estimates 

 of the true net energy values. 



Moreover, both Kellner and Armsby have practically worked only 

 with the steer, and the extent to which the values thus secured apply to 

 other classes of animals is a question. It has been shown that they 

 are too low for the dairy cow and too high for steers near the close of 

 the fattening period. AVith cattle upwards of 17 per ct. of the heat 

 value of the digested food is lost thru the fermentations which take 

 place in the digestive tract, especially the paunch. On the other hand, 

 there is but a small loss of this kind with horses or pigs. Hence, net 

 energy values found in trials with steers are more or less inaccurate 

 for horses and pigs. As Kellner himself states, in spite of the vast 

 amount of study given to the subject, there are still many gaps in our 

 knowledge of the actual net energy values of the different feeding 

 stuffs. While the present values are not exact measures of the value of 

 feeds for all classes of animals, they are, however, most helpful in 

 teaching great principles in the feeding of live stock. 



IV. The Scandinavian Feed-Unit System 



A system of feed equivalents, based mainly on extensive experiments 

 with milch cows at the Copenhagen Station, has been adopted in Den- 

 mark and other Scandinavian countries, especially by cow-testing asso- 

 ciations, for measuring the relative efficiency of milk production by 

 different herds and individual cows. The system is also occasionally 

 used with pigs, but rarely for other stock. It has been exceedingly 

 useful in co-operative efforts to improve dairy cattle and their feed- 

 ing — lines in which the Scandinavian farmers are leaders. 



The feed unit. — In the feed-unit system the value of the different 

 feeds is compared with the value of 1 lb. of standard grain feed, such as 

 corn and barley, which are taken as the unit of value. The amounts of 

 the various feeds required to equal 1 feed unit are given in Appendix 

 Table VI. 



The table shows that corn, wheat, rye, barley, hominy feed, the dry 



