230 PRODUCTIVE FEEDING OF FARM ANIMALS 
conducted at the different stations differed more or less, as did also 
the breeds represented in the respective trials. The results, there- 
fore, cannot be taken as absolute evidence of the capacity of the dif- 
ferent breeds for dairy production; but they doubtless show in a 
general way the relative value of the breeds in the dairy. We note 
that the breeds rank as shown below in regard to: (a) Yield of 
milk, (6) yield of butter fat, (¢) per cent of fat, (d) feed cost for 
100 pounds milk, (e) feed cost per one pound butter fat. 
a 6 c d e 
1. Holstein . Holstein Jersey Brown Swiss Brown Swiss 
2. Shorthorn Guernsey Guernsey Holstein Guernsey 
3. Brown Swiss Jersey Devon Shorthorn Jersey 
4. Ayrshire Shorthorn Shorthorn Guernsey Shorthorn 
5. Guernsey Brown Swiss Brown Swiss Am. Holderness | Holstein 
6. Am. Holderness | Ayrshire Am. Holderness | Jersey Am. Holderness 
7 Jersey m. Holderness | Ayrshire Ayrshire Devon 
8. Devon Devon Holstein Devon Ayrshire 
Individuality.—There are wide variations between individuals 
within the same breed as to the capacity for milk production and 
the quality of the milk produced. These variations are of much 
greater magnitude than the average differences between the breed. 
The great difference between individuals of the same breed as re- 
gards the amount of production is familiar to all; an average cow 
produces, say, 20 pounds of milk a day, containing three-fourths 
pound butter fat; a very good dairy cow, on the other hand, will 
yield over twice this amount, and exceptional producers will give 
more than quadruple the figures stated. But the average quality 
of milk of cows of the same breeds also differs greatly. The 
variations are probably larger within the Jersey and Guernsey 
breeds than in any other breed; there are thus cows or families 
within these breeds that produce milk of an average fat content 
above 6 per cent during the entire lactation period, while individuals 
.of other families will generally not go over 4 per cent. In the 
same way, we find some Holstein cows producing milk with over 
4 per cent fat, and others whose milk will contain less than 2.8 per 
cent, on the average, for a considerable period of time. 
Age of Cows.—This is not, on the whole, an important factor. 
As a general rule, heifers and young cows will give milk of a some- 
what higher fat content than older cows, but the differences in the 
average quality of the milk for a long period of time, say one year, 
are only within a few tenths of one per cent in the fat content, and 
there are some individuals whose milk changes with advancing age 
in the opposite direction from that stated. 
