1921.] 



Notices of Books. 



571 



NOTICES OF BOOKS. 



The Nutritive Value of. Lard.— (J. C. Druimnond, J. (ioldinfr. 

 S. S. Zilva and Kathariiir II. Cowanl : The BIOCHEMICAL JOURNAL. 

 Vol. XIV, No. (), Deceinl)er, 1920. Cambridge University Press.) During llie 

 last few 3-ears considerable attention has been devoted to the study of the 

 distribution of the so-called fat-soluble accessory factor, or vitamin A, in 

 naturally occurring oils and fats. Investigations tend to show that the oils 

 and fats derived from the animal kingdom are, as a rule, decidedly richer 

 sources of this essential dietary constituent than those prepared from vegetable 

 sources. Most authorities, however, regarded lard as an exception, having 

 found it practically devoid of vitamin A. Quite early in the study of growth- 

 promoting vitamins it was observed that butter fat was of much higher 

 nutritive value for growth than lard. This difference has been ascribed to the 

 fact that lard is a fat derived from storage depots, whereas butter fat is a 

 product of the synthetic processes of the mammary gland. The importance 

 of determining definitely why lard is thus deficient is, therefore, obvious. 

 The first series of experiments by the group of workers named above were 

 carried out on a litter of Berkshire pigs at the farm attached to University 

 College, Reading, while the rat feeding tests took place at University College, 

 London, and the results were published in the Biochemical Journal in December 

 last. 



It is now experimentally proved that the mannnalian organism does not 

 possess the power to synthesise the vitamin A, and that it is dependent upon 

 its diet for supplies of this essential factor. Hence it was concluded that 

 investigations should proceed along two lines, (1) a study of the influence of 

 the diet of pigs on storage of the vitamin in the fat depots, and (2) an 

 investigation of the influence of the technical processes of lard manufacture on 

 the vitamin when present in the pig fat. 



The results of the experiments are sunnnarised as follows : — 



(1) The pig is able to store up supplies of vitamin A in the body fat when 

 fed upon a diet containing ample supplies of that factor, as for example when 

 grass fed. 



(2) When the diet of the pig is delicient in vitamin A, as for example when 

 it consists almost entirely of toppings and whey, no appreciable amounts of 

 that dietary factor can be detected in the body fat. 



(3) The processes employed in the manufacture of lard on a large scale in 

 this country cause a very marked destruction of the vitamin present in the pig 

 fat. 



(4) The low nutritive value of lard is therefore believed to be due to 

 two causes. First, the diet usually given to fattening pigs in this country is 

 seldom rich in vitamin A, so that the average sample of pig fat contains little 

 or none of that substance. Secondly, the processes of lard manufacture 

 undoubtedly cause the destruction of much of the vitamin present in the 

 original pig fat, proba[)ly owing to the exposure of the fat to oxygen at liigh 

 temperature. 



Poultry Keeping. -(C. A. Flatt. London: Methuen c^- ("o. Price 

 5s. 6d.) Poultry farming is a highly specialised business, an<l. as sucli, 

 requires considerable practical experience if it is to be made a success. 



