BODY TISSUES 325 



nutrition arc factors which afTcct the quantity of fat protluced and the 

 fatty acid distribution in the triglycerides. 



The ash of milk contains all the elements required for growth of 

 the young mammal but not always in optimal quantities. Iron and 

 copper supplementation is sometimes required in the growing young 

 to prevent anemia. Milk contains most of the vitamins in greater or 

 smaller amounts. Generally it is deficient in C and D, although there 

 are great species variations. The diet of the lactating mammal is also 

 a factor in vitamin content. 



The early secretion of the mammary gland, called colostrum, is quite 

 different from the milk produced later. Colostrum is relatively high 

 in protein and low in carbohydrates, fats, and ash. The globulin con- 

 tent of colostrum is relatively high, as is the antibody titer. The blood 

 of the newborn mammal has a very low antibody titer, which means 

 that it is susceptible to pathogenic organisms. The antibodies of 

 colostrum milk are quickly absorbed, but the process of absorption is 

 poorly understood. In the older mammal, transfer of such large par- 

 ticles does not occur so extensively. Colostrum may be a waste product 

 which follows regeneration of the secretory tissues of the mammary 

 glands. As soon as lactation ceases, the globulin fraction of the fluids 

 of the glands increases and casein decreases. The globulin content of 

 such tissue remains high until the next lactation period. The anti- 

 bodies of colostrum milk may be produced to protect mammary tissue 

 during the interim between lactation periods. 



REFERENCES 



A Textbook of General Physiology, fifth edition. P. H. Mitchell. McGraw-Hill 

 Book Co., New York, 1956. 



The Physiological Basis of Medical Practice, fifth edition. C. H. Best and N. B. 

 Taylor, ^\'illiams and VVilkins Co., Baltimore, 1955. 



Textbook of Physiology and Biochemistry, third edition. G. H. Bell, J. N. David- 

 son, and H. Scarborough. E. and S. Livingstone Ltd., London, 1957. 



Biochemistry and the Central Neivous System. H. Mcllwain. J. and A. Churchill 

 Ltd., London, 1955. 



