164 Animal Husbandry 
come up to the bottom of the neck. Whirl two minutes. Add 
hot water sufficient to bring the top of the fat nearly to the top of 
the graduation on the neck of the bottle. Whirl one minute. 
The fat should form a clear column free from black or white patches 
in the neck of the bottle. 
271. Reading the percentage of fat.— Keep the fat warm. 
Hold the bottle by the upper end of the neck, letting it hang in a 
perpendicular position on a level with the eye. Read the mark 
at the top and bottom of the column of fat. The difference be- 
tween these is the percentage of fat in the milk. For example, 
if the top reading is 8.2 and the bottom 5.0, then the milk tests 
3.2 per cent. 
Much care should be exercised in dleaning the test-bottles as 
they should be perfectly free from dirt when used. 
272. Testing associations. — In those sections of the country 
in which dairying is extensively practiced, the forming of testing 
associations will prove very advantageous. Cow-testing associa- 
tions are organizations of farmers having for their object the deter- 
mination of the production of the individual cow in the herd. 
273. General plan of organization. — A number of dairymen, 
twenty to twenty-five, having a total of 300 to 600 cows, effect 
an organization, elect officers, adopt a constitution and by-laws, 
and give the officers power to employ a man to do the testing. 
This tester visits each of the herds once a month, weighs the milk 
of each cow for a period of twenty-four hours, takes the samples 
of the same and tests for percentage of fat. In some cases the 
tester weighs the feed of each cow and figures the cost of the ration. 
The tester makes a complete record for each cow in the herd, 
of the amount of milk, the percentage of fat and total fat, and 
the food consumed, leaves a copy of this record with the dairyman, 
and proceeds to the next herd, to return again in about one month. 
In addition he gives all the helpful suggestions possible, such as 
the successful practices of the other members of the association. 
The entire cost to the dairyman is approximately one dollar 
