ANNUAL REPORT, 1931 231 



maximum roughage and low grain (1 pound of grain to 4>^ pounds milk) fed to 

 one group of cows, and minimum roughage and high grain (1 pound of grain to 

 2J^ pounds milk) fed to another group, upon the economy of milk production, 

 and the condition of the cows as regards appearance, live weight, and breeding. 

 The roughage has consisted of first -cut hay, rowen, silage and green forage fed 

 in different amounts; and the grain, of a mixture of wheat bran, ground oats, 

 corn meal, gluten feed, and cottonseed meal, mixed in different proportions for 

 the two groups. A statement of the results from October, 1928, through Feb- 

 ruary 1, 1931, follows: 



High Low 



Roughage Roughage 

 Proportion grain to total feed, dry matter (per cent) : 



October, 1928 to October, 1929 21.5 36.5 



October, 1929 to February, 1931 19.1 35,3 



Dry matter required to produce 100 pounds milk (pounds): 



October, 1928 to October, 1929 107 97 



October. 1929 to February, 1931 118 107 



Net energy required to produce 100 pounds milk (therms): 



October, 1928 to October, 1929 010 600 



October, 1929 to February, 1931 6.39 636 



Feed cost of 100 pounds milk: 



October, 1928 to October, 1929 $1.74 $1.75 



October, 1929 to February, 1931 1.70 1.67 



It is clear that the high-roughage cows required more dry matter to produce 

 a definite amount of milk than the low-roughage cows. The calculated therm& 

 of net energy, however, did not vary much for either group. When it came to a 

 matter of feed cost, the results were about the same in each case on the basis of 

 market price for all feeds. While for a definite amount of feed the low-roughage 

 ration produced more milk than the high-roughage ration, the feed cost per unit 

 of milk was about the same. 



It might be added that the cows in both herds kept in good condition and did 

 not show breeding troubles, although it must be admitted that the low-roughage 

 cows presented the better appearance. 



Mineral Requirements for the Growth of Dairy Heifers. (J. B. Lindsey 

 and J. G. Archibald). Results of one phase of this project have been published 

 in the Journal of Agricultural Research 42:883-896, June 15, 1931, in an article 

 entitled, "The calcium requirements of dairy heifers." 



Work on the phosphorus requirements is being actively pursued, although it 

 has been seriously interfered with by the loss of two heifers which reacted to the 

 tuberculin test in February. Forty metabolism balance trials with eight heifers 

 have been completed. Four of these heifers have received a basal ration low, in 

 phosphorus, while for the other four the basal ration has been supplemented 

 with sufficient organic phosphorus to double the amount of that element fed. 

 The work has not reached a stage which warrants reporting any results. During 

 the year the capacity of the equipment for conducting balance experiments has 

 been doubled by the addition of two more metabolism stalls. 



Studies in the Chemistry of Pastvire Grasses. (J. G. Archibald and E. 

 Bennett). A final report summarizing three j^ears' work on the original project 

 reported on in 1929 and 1930 (of which the present project is an outgrowi;h) 

 has recently been prepared for publication. 



