616 
Joumal oj Agricultural Besearch voi. xxix, no. u 
As a matter of convenience, the 
qualitative changes in the mixture of 
amino acids in the whole blood rather 
than in the blood plasma have been 
studied. The conclusions, that have 
been reached, however, are undoubt¬ 
edly applicable to the blood plasma as 
well. 
the ration was changed; but in Experi¬ 
ment VIII, where the energy of the 
ration and the plasma amino N were 
higher, the total amino N did not rise. 
In fact, there was no significant change 
in plasma amino N throughout the 
latter experiment until after the corn- 
milk protein ration of period 3 had 
Table X .—Experiment VIII , cow Change in quality of protein in ration ;; 
no change in quantity 
Milk (daily) 
Amino N ° 
o 
£ 
.2 
cS 
Pi 
1 
1 
1 
1 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
3 
3 
3 
3 
3 
3 
3 
3 
3 
3 
3 
Date 
1921 
Nov. 5, 6_. 
Nov. 8_ 
Nov. 10-11 
Nov. 12_ 
Nov. 13_ 
Nov. 14_ 
Nov. 15_ 
Nov. 17_ 
Nov. 18_ 
Nov. 19_ 
Nov. 20— 
Nov. 21_ 
Nov. 22_ 
Nov. 23__.. 
Nov. 24_ 
Nov. 25.... 
Nov. 26_ 
Nov. 27.... 
Nov. 28_ 
Nov. 29_ 
Nov. 30... 
Dec. 1_ 
Dec. 3_ 
Dec. 4_ 
Dec. 5_ 
Yield 
Fat 
Kg. 
7.01 
7. 21 
6.94 
6. 89 
6.89 
6.35 
6. 26 
5. 72 
5.40 
5. 26 
5.76 I 
5.44 
5.44 ! 
5. 22 
5.49 
5.90 
6. 21 
6.49 
6.49 
6.26 
6.26 
6. 44 
6. 53 
5.94 
5.44 
Per cent 
5. 51 
5. 57 
5. 77 
5. 73 
5. 75 
5. 62 
4. 98 
6.59 
6. 55 
6.19 
7.44 
6 . 21 
6.04 
6. 42 
6. 22 
5.96 
5.43 
5.07 
5. 69 
5.02 
5.02 
5. 07 
5.35 
5. 35 
5. 54 
Gm. 
386 
402 
400 
395 
396 
357 
312 
376 
354 
326 
429 
338 
328 
335 
341 
351 
338 
329 
369 
314 
314 
326 
350 
318 
302 
| Blood 
Nitrogen I (mg. per 
| 100 c. c.) 
i 
Plasma 
(mg. per 
100 c. c.) 
Trypto¬ 
phane 
(mg. per 
100 c. c.) 
Per cent 
0. 626 
.632 
.625 
.651 
.647 
.679 
.672 
.738 
.719 
Gm. 
43.8 
45.6 
41.0 
44.9 
44.6 
43.2 
42.1 
42.2 
38.8 
4.37 
4. 20 
2. 46 
2.24 
0. 34. 
.692 
.672 
.688 
.658 
.623 
37.7 
36.5 
35.9 
36.1 
36.7 
4. 22 
2.37 
.'45- 
. 637 41. 3 
. 631 40. 9 
.638 
.626 
.653 
41.1 
37.2 
35.6 
4.14 
4. 57 
2.28 
3.08 
. 66 ' 
.69' 
* Average difference in duplicate amino-N determinations in blood 2.9 per cent, and in plasma 1.6 per¬ 
cent. 
Although it was found, as was to 
have been expected, that a high plasma 
amino N is, in general, associated with 
a dietary protein mixture of low effi¬ 
ciency, there are a number of circum¬ 
stances in which this might not be true. 
Thus in Experiments VII and VIII 
(Tables IX and X) in changing from 
the first to the second period the quality 
of the dietary protein was reduced with 
no change in quantity; the milk yield 
was reduced; the concentrations of 
certain amino acids in the blood plasma 
wer„e reduced, whereas the concentra¬ 
tions of others were increased; and, 
whether the total plasma amino N 
would increase or not, one can readily 
see, would, largely depend upon the 
responsiveness of the mechanism des¬ 
troying these latter amino acids to the 
increases in their concentrations. In 
Experiment VII, where the energy of 
the ration and the plasma amino N 
were low, the total amino N rose when 
been fed for a considerable time. The 
abrupt rise from 2.28 to 3.08 mg. per 
100 c. c. at this time probably marks 
a change in the storage capacity of the 
tissues. 
CHANGES IN THE YIELD AND COM¬ 
POSITION OF MILK 
Figure 3 shows that in Experiments 
I to V, when the protein or energy, or 
both, in the rations were reduced, the 
milk yields dropped decidedly; figure 
4 shows that this effect on the milk 
yields was reversed when these dietary 
changes were reversed; and Figure 5 
shows that the milk yields varied with 
the quality of the dietary protein in 
Experiments VII and VIII, in which 
the quality of the dietary protein was 
changed without change in its quantity 
or in the energy of the ration. 
Figures 6 to 13 show the changes in 
the composition of the milk in all ex- 
