si^oa 
Autuqpj A , ail I(stII0 ^ 
;o'J3m t Ar. 
Vol. LXXVIII. 
* , v r, 
IMiblislied Weekly by The Rural Publishing C'o.. 
333 \V. 30tU St., New York. Price One Dollar a Year. 
NEW YORK, MAY 31, 1919. 
Entered as Second-Class Matter. June 26. 1873. at the Post 
Office at New York. N. Y.. under the Act of March 3. 1879. 
No. 4536. 
Seasonal Variation in Milk Composition 
What Happens to the Cow in Summer? 
Part I. . - , 
D issatisfied producers:—T he time of 
year is at hand when the farmer who is selling 
liis milk cm a straight butterfat basis or a flat rate 
per 100 ll»s. plus a premium for butterfat begins to 
wonder, and express himself in strong language to 
his neighbors and others, that he cannot see why 
his test should be getting less all the time. The 
opinion he has of the concern buying liis milk, and 
fault. Plenty of data are now available to sub¬ 
stantiate this point thoroughly, and such data should 
be of interest to the milk producer. The tables that 
follow are compiled from Storrs, Conn., Bulletin 94. 
Table I shows the effect of seasonal variation on 
the per cent of fat and solids not fat for eight cows 
calving iu the month of January; 
Table I. 
Per Cent 
Month 
Jaunary 
February 
March .. 
Fat 
3.91 
3.9:; 
Per Cent 
Solids Not Fat 
8.70 
8.77 
8.50 
January to 3.01 iu June and 3.62 in July, and the 
solids not fat from 8.70 to S.23 and 8.10 respectively. 
It should be noted that the solids not fat content is 
affected about twice as much as the fat, and that 
cows giving average testing milk (3.7 to 4 per cent) 
may fall below the common S.5 per cent solids not 
fat standard. It is seen in August. September and 
October that the composition of the milk improves. 
This is due to both coming of cooler weather and 
advancing lactation. Another point to note particu¬ 
larly at this time is that March, April and May 
are the months when the test begins to go down. 
Guernsey Coir Yivolette ?</ 60799. Fin. 2)7. See Pag 9.10 
of the operators of the Babcock test, possibly of the 
test itself, are anything but complimentary. As a 
matter of fact, while an operator of the test may 
make an occasional slight error, in general the Bab¬ 
cock test can be relied upon the year around to give 
an accurate and just basis on which to sell our 
milk. 
DATA FROM STORRS.—Owners of low-testing 
cattle are sometimes taken to account by State dairy 
commissioners during the Summer for selling milk 
that is below the standard for per cent of fat or 
solids not fat. or both. To be sure the test will 
be lower during the Spring and Stumper months, 
titan during the Winter, but it seems to be the cow’s 
April . 
• • • • • 
3.68 
8.50 
May . 
_ 3.71! 
8.62 
June . 
_ 3.61 
8.23 
J uly . 
..... 
_ 3.62 
8.10 
August . 
8.24 
S.53 
October . 
_ 4.02 
8.72 
MARKED CH 
VNGE 
S.—It is quite well understood 
that milk tests 
lower 
during the first 
few months 
of lactation and increases in richness towards the 
end of the period. For that reason the data on these 
Winter calving cows have been selected to bring out 
the point. It might be stated that these data were 
collected by making fat and lactometer determina¬ 
tion^. at regular intervals three times eaeh month. 
It will be uo’ted "that the fat drops from 3.96* in 
ADVANCED LACTATION.—Should a man hav¬ 
ing his herd freshening in Summer or Fall also 
expect this reduction in test the following Spring, 
or will the fact that the cows will be well advanced 
in lactation prevent it? Table II shows some figures 
that answer this question: 
Table 
J an. Feb. 
II. 
Mar. 
April 
May 
June 
tfc Fa t. 
% SNF. 
July 
Aug. 
Sept. 
4.01 
8.73 
Oct. 
3.83 
3.80 
Nov. 
3.92 
8.76 
Dec. 
% Fat. 
4.76 
4.69 
4.53 
4.22 
4.67 
4.76 
% SNF. 
S.57 
8.94 
S.74 
8.66 
9.12 
8.97 
Jan. 
Feb. 
Mar. 
April 
Mav 
June 
%, Fat,. 
4.73. 
4.83 
4.76 
4,63 
3.65 
4.51 
U83 
C SNF. 
- 9.01' 
9.19 
1 S.97 
S.S6 
S.76 
