114 EXPERIMENT STATION. [Jan. 



one on a diet approximately sufficient to furnish protein for 

 maintenance plus that contained in the milk, and the other on 

 a diet containing some ^ pound more protein daily than the 

 maintenance and milk requirements. 



Duration of the Experiment. — The experiment was planned 

 to continue substantially through a milking period, or until the 

 animals were so far advanced in lactation as to cease to respond 

 to the influence of food. 



Weighing the Cows. — Each animal was weighed for three 

 consecutive days at the beginning of the period, and for three 

 days each two weeks thereafter. 



Sampling Feeds. — The hay fed was sampled at the begin- 

 ning of the period for each pair of cows, and each two weeks 

 thereafter. The samples were placed in glass-stoppered bottles, 

 taken to the laboratory and dry-matter determinations made 

 at once. The method of sampling has been described in preced- 

 ing experiments. 



Each kind of grain was sampled daily during the process of 

 weighing out, and the composite samples preserved in glass- 

 stoppered bottles. Dry-matter determinations were made once 

 each month, and the monthly samples composited. 



Character of Feeds. — It was intended to procure one lot 

 of ha}' of the same quality sufficient to last during the entire 

 experiment. Owing to several unfortunate circumstances this 

 was not possible. Three different lots were secured, and com- 

 posite samples of each analyzed. The digestibility was not 

 determined, but approximate coefficients applied, depending 

 upon the analysis and general appearance of the hay. The 

 several grains were procured in large amounts and average 

 digestion coefficient applied. 



Sampling Mill'. — The milk of each cow was sampled for 

 five consecutive days at the beginning of the period, and each 

 two weeks thereafter. It was tested for total solids, for fat 

 by the Babcock method in duplicate, and for nitrogen by the 

 Kjeldahl method. 



