Dec. 17,1917 
Influence of Age of Cow on Milk and Milk Fat 
655 
Table IV .—Influence of plane of nutrition during growth on percentage of fat in milk 
of first two lactation periods 
Group 
Num¬ 
ber of 
cows. 
Breed. 
Plane of nutrition 
Fat in milk. 
Cows showing highest test 
in— 
No. 
during growth. 
First 
Period. 
Second 
Period. 
First 
Period. 
Second 
Period. 
Station¬ 
ary. 
1 . 
2 . 
8 
IO 
Jersey. 
Heavy fed. 
Light fed. 
Per cent. 
5-32 
5 * 13 
3-35 
Per cent. 
5 - °7 
e. 21 
Per cent. 
62. 5 
20. O 
Per cent. 
25.O 
60. O 
Per cent. 
12. 5 
20. O 
3 . 
7 
Holstein. 
Heavy fed. 
3 -10 
IOO. O 
0. 0 
O. O 
4 . 
7 
.do. 
Light fed. 
3 - 05 
3. 00 
42. 8 
14.4 
42. 8 
The influence of the plane of nutrition during growth, shown in Table 
IV, is more striking. The data indicate that this factor may be of 
importance in connection with the average fat test for the first lactation 
period. The light-fed Jerseys showed both a lower average test in the 
first lactation period and also a less frequent tendency for this period 
to show the highest test, while the heavy fed Jerseys showed exactly 
opposite results. These data seem to justify the tentative explanation 
already advanced as to why the Jersey group as a whole showed different 
results from the Holstein and Aryshire groups. The data in Table IV 
show, in addition, that the strong breed tendency for the Holsteins to 
show a higher average test in the first lactation period than in any 
subsequent period was materially diminished by light feeding during 
the growth of the animals. It may also be pointed out that the light 
feeding of the animals of both breeds was by no means extreme, although 
it was widely different from the heavy feeding carried out with the 
other animals in the experiment. 
COMPOSITION AND PROPERTIES OF MILK OF AGED COWS 
The fact that certain animals in the Jersey herd of the Missouri 
Station had the breed characteristic of persistent milking developed to 
a marked degree has made it possible to examine the composition and 
properties of the milk of two cows which had attained an advanced 
age. Complete analyses of the milk fat of cow 124 were made on two 
occasions in her sixteenth year and during her twelfth lactation period, 
and again on two occasions in her nineteenth year, when she was in 
her thirteenth lactation period. Similar analyses were made of the 
milk of cow 16 when she was 14 years of age, and during her ninth 
lactation period. Two analyses have also been made of the milk of 
cow 403, of the Dairy Shorthorn breed, when she was 11 years of age, 
and during her fourth lactation period. These data are presented in 
Table V. 
