USES OF FEED BY ANIMALS 39 
For fairly mature fattening animals (e.g., two- to three-year- 
old steers) 3.5 therms per pound of gain in live weight are believed 
to be sufficient, and a similar amount of digestible protein is 
recommended as in feeding for normal growth. 
Requirements for Milk Production—For the production of a 
pound of average milk containing about 13 per cent solids and 4 
per cent fat, 0.05 pound of digestible protein and 0.3 therm of energy 
value are considered ample, milk rich in fat and in total solids re- 
quiring more nutriment than milk containing more water or a lower 
percentage of fat. Recent work by Haecker and by Eckles has fur- 
nished additional data on this point. The results obtained by 
these investigators are important contributions to the subject of 
feed requirements of dairy cows. The tentative statement of the 
requirements for the production of milk containing different per- 
centages of butter fat given by Hckles is as follows :° 
Feed Requirements for Different Grades of Milk 
[ Per pound of milk 
Per cent fat 
in milk Digestible Energy values, 
protein, pounds therms 
3.0 .050 26 . 
4.0 1055 30 
5.0 062° .36 
6.0 .070 45 
The method of calculating rations according to the Wolff-Leh- 
mann and Armsby standards will be explained fully when the uses 
of nutrients by different animals and the various feeding stuffs 
available for farm animals have been discussed. 
QUESTIONS 
1. What do you understand by the maintenance requirements of animals? 
2. Give maintenance ration for a 1000-pound cow according to (a) the 
Wolff-Lehmann standard, (b) the Armsby standard. ; 
3. Give the feed requirements for fattening swine according to the Wolff- 
Lehmann standard. 
. What is meant by nutritive ratio? Give an example. 
. Show how the feed requirements for a dairy cow are calculated according 
to the Armsby standard. 
oP 
*Missouri Research Bulletin 7. 
