672 EXPERIMENT STATION RECORD. [Vol.86 



came from the particular concentrate under investigation. Tlie total protein 

 intake constituted about 10 per cent of tlie dry matter of tlie ration and the 

 nutritive- ratio was about 1 : 8. 



With a daily production of from 40 to 45 lbs. of milk containing from 10 to 

 12 per cent of total solids, a negative nitrogen balance persisted throughout 

 the experiments, this negative balance being very much larger with the gluten 

 feed ration than with any of the other concentrates. Only during the period 

 of skim milk powder feeding was one of the animals storing nitrogen. " In 

 spite of this long negative balance milk secretion continued at the expense of 

 catabolizing tissue. The total yield and total solids of the milk declined 

 slightly after two months of continuous negative nitrogen balance. 



" There was a marked difference in the utilization of the concentrates : 

 Gluten feed showed a percentage efficiency of 45, oil meal 61, distillers' grains 

 60, casein 59, and skim milk powder 60. These data represent the efficiency 

 in the mixture used. 



" Possible errors in calculation may arise from the supplementing effect of 

 the catabolizing tissue, thereby raising the figures above their true value, but 

 nevertheless they do have comparative worth. . . . These studies furnish 

 additional evidence that the nutritive ratio or plane of protein intake for milk 

 production may vary according to the nature of the concentrates and basal 

 ration used." 



The influence of the ration on the composition of the urine of dairy cows, 

 T. E. Keitt {So7ith Carolina Sta. Rpt. 1916, pp. 57-^8).— In these investiga- 

 tions, three lots of 1 aged cow and 1 heifer each were fed from June 19, 1913, 

 to March 18, 1915. Lot 1 received a balanced ration of linseed meal, corn meal, 

 and wheat bran; lot 2 cottonseed meal and linseed meal (1:4); and lot 3 

 cottonseed meal. The rations of all the lots were supplemented with pasturage 

 and corn silage when the pasturage was scant. 



The urine of each of the animals was secured for various 24-hour periods 

 throughout the experiment and the amounts voided per diem, together with 

 the urea content, are tabulated. Analytical data are also tabulated for the 

 urine of each cow for each of these 24-hour periods, regarding the specific 

 gravity, acidity, chlorids, phosphates, albumin, acetone, sugar, indican, total 

 solids, ash, free ammonia, nitrogen, lime, and color. 



In the case of the cow in lot 1 there seemed to be a direct relation between 

 the color of the urine and its specific gravity — the higher the specific gravity 

 the deeper the color. A short time before calving the specific gravity of the 

 urine ran very low and at this time all of the constituents were quite low, 

 probably due to large dilution. There seemed to be no definite relation between 

 the total ash content and the content of lime and of phosphorus. The total 

 solids varied in a general way with the specific gi-avity. 



The phosphorus content of the urine of the heifer in this lot was lower than 

 that of the cow, but the contents of nitrogen, urea, free ammonia, and lime 

 were higher. The contents of nitrogen, urea, and free ammonia ran lower in 

 these two animals than in those fed the highly nitrogenous feed, indicating that 

 a highly nitrogenous feed throws more work on the urinary system of the 

 animal and that the excess of nitrogen above the balanced ration is metabolized. 



With lot 2 the relation between color and specific gravity did not hold. 

 There was not much lowering of the specific gravity of the urine previous to 

 calving in this lot. After two months of the experiment had elapsed there was 

 a noticeable increase in the urea content of the urine of this lot, this being true 

 Irrespective of the fluctuations in volume of the urine voided. This was true 

 of all animals receiving high protein rations, but it did not hold good for the 

 animals on the balanced ration. 



