170 NORMAL MILK : ITS ADULTERATIONS, ETC. 



It cannot be too strongly insisted on that the calculated 

 standards apply only to the mixed milk of a number of cows ; 

 the milk of a single cow may be below these figures to a serious 

 extent. As this case is one which but rarely occurs — the sale of 

 milk being almost entirely confined to the production of herds 

 — it is not necessary to make any allowance for the greater 

 variations of quality of the milk of individual cows. 



Appeal to the Cow. — In cases of doubt it is advisable to 

 resort to what is known as " appeal to the cow," or the " stall 

 or byre test." This consists in having the cow — or cows — • 

 milked in the presence of a responsible witness who can certify 

 to the absolute genuineness of the milk, which is analysed and 

 compared with the suspected sample. It is desirable, if possible, 

 that the milk of the morning and evening meals should both be 

 examined. To make the test as fair as possible^ .tha cows should 

 be milked by their usual milkers at the same time of day as the 

 previous sample, and under the same conditions ; the test should 

 be carried out at as early a date as convenient, and care should 

 be taken that the meteorological conditions are nearly alike, as 

 a poorer milk is yielded in warm, damp weather than if it is clear 

 and frosty. The test should not be carried out on a Sunday or 

 Monday, or on a public holiday or its morrow, unless the previous 

 sample was taken on a similar day, as it has been shown that the 

 irregularity in the time of milking — which occurs on such days 

 — afiects the quantity and quality of the milk ; any serious 

 divergence from the average quantity of milk yielded may be 

 looked upon as throwing doubt on the reliability of the test. 

 The witnesses must be specially careful in seeing that the cows 

 are milked out, and that nothing occurs likely to disturb the 

 equanimity of the cows, such as undue commotion or noise. If 

 the milk is cooled, it is the duty of the witnesses to satisfy them- 

 selves that the refrigerator does not leak, as well as to see that 

 all vessels into which milk is received are clean and dry. 



This test, if properly carried out by competent witnesses, is 

 very reliable ; if the suspected sample were genuine, milk will be 

 yielded of approximately the same composition at the appeal to 

 the cow ; everything, however, depends on the competency of 

 the witnesses. 



Influence of Feeding and other Conditions on the 

 Composition of Milk.— If the food given to the cattle is suffi- 

 cient both in quantity and ratio of constituents no appreciable 

 variation in the composition of the milk is found on changing 

 the food. The author has noticed that, if the food given makes 

 the cows scour, the milk is likely to be low in fat, and the per- 

 centage of fat is raised by the addition of a more binding food — 

 e.<j., cotton cake — to their ration. 



