210 . THE CREAMERY PATRON'S HANDBOOK. 



theory, for at the beginning and at the end of lactation the albumin which 

 is normally less than one-seventh of the casein, is actually in excess of it, 

 and albumin is a normal constituent of both blood and milk. Smith says 

 casein is developed at the expense of the albuminous cell contents, since it 

 is absent from the blood. The alkali albuminate is derived from the break- 

 ing down of the protoplasm and nuclein, which is always found as a part 

 of the casein and is derived from the nucleus which disappears in the process 

 of secretion. The proportion of casein in the milk is increased by greater 

 perfection in the activity of the cells. In the formation of colostrum, 

 the albuminoid matter is greatly in excess of that after secretion is well 

 established, and with the decrease of albumin, there is a proportionate 

 increase in casein. A ferment has been extracted from the mammary gland 

 which will convert albumin into casein. 



The water, no doubt, passes directly from the capillaries into the milk 

 follicles, and carrying with it the mineral constituents in solution. 



The functions of the mammary gland are performed involuntarily. 

 There seems to be some connection between the mammary gland and the 

 central nervous system, but how much control can be exercised by will, 

 has not been determined. Locally the stimulus seems to be the empty 

 milk duct, for when the ducts become full, the secretion is partially 

 checked, but is considerably stimulated during the process of emptying. 



INFLUENCES AFFECTING MILK PRODUCTION. 



BREED. Heredity has a most marked effect upon milk production. 

 The different breeds are the result of the selection of animals of certain 

 types, and some have been selected to produce very rich milk, others large 

 quantities of milk and in others no attention has been paid to this quality. 

 The difference in the quality of milk due to breed, includes not only the 

 amount of fat, the color and melting point of the fat, but also the size of 

 the milk globules. In some breeds the globules are large, in some they are 

 small, and in some they may be mixed, large and small. While the breed 

 has a most marked influence, there is also considerable variation of the in- 

 dividuals in each breed. 



No figures are available, that give a good index to the amount of milk 

 and the period of lactation in the different breeds of cattle in this country. 

 The only animals of which we have record are individuals mainly owned by 

 Experiment Stations, or in breeding establishments, which are of more than 

 average in quality. 



HEREDITY. As a breed represents only the characters of individuals 

 fixed by selection for successive generations, it is but natural that we should 

 find like influences in families, but in a less marked degree. Heredity has 

 its effect in stamping individuality, both in the quantity and quality, and no 

 stronger proof is needed than the records of the noted families of the breeds. 



AGE. Age will influence the quantity of milk. From two until five 

 years there is a gradual increase in the quantity, after which time it remains 



