Dec. 15,1924 
Composition o f Diet } Blood , and Milk 
617 
cept Experiment IV, where no determi¬ 
nations were made in period 1. The 
results may be summarized as follows: 
1. Experiments II and V show that 
the concentration of lactose in the milk 
of an individual cow is exceedingly con¬ 
stant and is unaffected by wide varia¬ 
tions either in the quantity and quality 
of the dietary protein or in the quantity 
of carbohydrate in the ration. It varied 
in these two experiments from 5.23 per 
cent to 5.42 per cent, or 3.6 per cent 
difference. 
without altering the energy content of 
the ration, reduces the concentrations 
of milk N and fat. 
4. In Experiments VII and VIII, 
where only the quality of the dietary 
protein was changed, the concentra¬ 
tions of milk N and fat were higher 
when the dietary protein was qualita¬ 
tively less well adapted to the secretion 
of the milk proteins. 
5. In all these experiments where* 
only the protein of the ration was al¬ 
tered there is in general a parallelism* 
Fig. 3—Experiments I-V. Change of milk yield when amount of protein or energy, or both, were 
reduced in the ration after period on adequate ration. The yield before the ration was changed is 
taken as 100 per cent 
2. A reduction in the energy content 
of the ration, either alone (Experiment 
II) or together with the protein (Ex¬ 
periment I), has no constant tendency 
to reduce the concentration of milk fat, 
but does effect a reduction in the con¬ 
centration of milk N. In Experiment I 
the concentration of milk fat was higher 
on the ration low in its protein and 
energy content than on the original 
ration. 
3. A reduction in the quantity (Ex¬ 
periment III) or quantity and quality 
(Experiment V) of the dietary protein, 
between the changes in the concentra¬ 
tion of milk N and fat that is certainly 
quite evident. 
RELATION BETWEEN THE COMPO¬ 
SITION OF BLOOD AND THE 
SECRETION OF MILK 
The results of these experiments 
show, as was to have been expected, 
that the relations between the diet, 
the composition of the blood, and the 
secretion of milk are exceedingly 
complicated. We are still very far 
