634 IOWA DEPARTMENT OF AGRICULTURE 



a regular route, so that it will be impossible for the dairyman to know the 

 exact day on which to expect him. 



In weighing the milk a "shotgun" can — a can 8 inches in diameter and 

 20 inches high— is used. It holds 35 pounds and has straight sides, with 

 a handle near the bottom so that it may be easily emptied. The empty 

 can should weigh even pounds so that mistakes in subtraction may be 

 avoided. It has straight sides so that accurate samples may be obtained 

 by the use of an instrument known as a "milk thief," as with an ordinary 

 milk pail with a flaring top an accurate sample might not always be 

 obtained, owing to the greater area of the milk at the surface than at 

 the bottom. If the herd is large it is desirable to have two of these 

 cans with straight sides so that the milker may pour the milk into 

 them and proceed to milk the next cow without waiting for the tester 

 to weight and sample the milk. In this way time is saved in the stable. 



For weighing the milk a special spring balance is used, weighing 

 to 30 pounds and having two indicators, one of which is adjustable 

 and should be set at zero when the weigh can is on the scales. The 

 balance is graduated in tenths of pounds and is frequently tested so 

 that any stretching of the spring may be immediately detected. The 

 milk is poured from pail to pail two or three times and the sample 

 for testing is taken immediately after such pouring is completed. 



The fat determinations are invariably made at the farm. The reason 

 for this is the difficulty in transporting the samples to the creamery 

 without leakage, churning of the milk in hot weather, etc., any of 

 which renders correct determination difficult. Another and equally import- 

 ant reason is that the dairyman becomes more interested in the work 

 if it is done on the farm. He usually assists the expert with the testing 

 and in this way acquires an understanding of the principles and the 

 use of the Babcock test which he would not otherwise get. 



If a cow is in heat or temporarily out of condition on the testing 

 day, no sample of her milk is taken, as there is usually an abnormal 

 fluctuation in the fat content at such times, and the calculations based 

 upon tests taken then may he several pounds too high or too low. The 

 fact of such temporary abnormal condition is recorded in the herd book, 

 and the average of the preceding and the following months' test is used 

 in the calculations. 



Milk from fresh cows for the first three days can not be considered 

 normal, and calculations based upon a test at that time may be very 

 erroneous. It is the rule not to use the test of a cow's milk for cal- 

 culations until she has attained a normal condition. If she has not 

 reached this condition on testing day the following month's test is 

 used as a basis for calculation the yield for the first three days is 

 omitted from the record, and the cow is considered as being dry when 

 nearing the end of the lactation period. 



The day upon which the test is made is called the testing day, and 

 the records obtained on that day are used as a unit for each day in 

 the period extending equal lengths of time on both sides of the testing 

 day. This period is called the testing period, and is so marked off 



