240 PRODUCTIVE FEEDING OF .FARM ANIMALS 
according to Wolff-Lehmann and Armsby are given at the begin- 
ning of this chapter. The former standards have been modified 
by Haecker,® who has calculated the amounts of digestible protein, 
carbohydrates, and fat required for the production of a pound of 
milk testing 3 to 6.5 per cent as follows: 
Requirements for Milk of Different Richness 
Digestible 
Protein Carbobyarstes 
For maintenance per 1000 pounds.............. .700 7.225 
Per pound of milk testing 3 per cent........... .047 238 
4 per cent........... .054 287 
’ 6 per cent.......... .060 1304 
6 per cent........... .067 383 
6.5 per cent........... .072 -405 
* Given separately in Haecker’s standards. 
In addition to giving digestible protein, carbohydrates, and fat 
to the third decimal place, Haecker calculates the requirements 
per pound of milk for differences in fat contents of only 0.1 
of 1 per cent between 3.0 and 6.5 per cent. In view of the 
great differences in the returns made by different cows from the 
feed eaten, and the great variations to which feeding stuffs are 
subject, both as regards composition and digestibility, it would 
seem rather unnecessary to make such fine distinctions. Eckles ** 
has modified the Armsby standards according to the fat’ content 
of the milk produced, allowing 0.05 to 0.07 pound digestible pro- 
tein and 0.26 to 0.45 therm per pound of milk testing 3 to 6 per 
cent (p. 39). 
The American Practical Feeding Ration—The author pub- 
lished in the nineties the following so-called “ American Practical 
Feeding Ration ” for dairy cows, as a result of studies of the methods 
of feeding and the experiences of more than one hundred promi- 
nent American dairy farmers with regard to the amounts and 
character of the feed which will be likely to give the best and most 
economical results under our conditions when fed to good dairy 
cows in full flow of milk and of an average weight.of 1000 pounds: 17 
% Minnesota Bulletin 130. 
16 Missouri Research Bulletin 7. 
17 Wisconsin Bulletin 38. 
