ANIMAL HUSBANDRY. IO7 



when digested and absorbed. From the results of some pre- 

 hminary experiments which have been done on the goat it looks 

 as if this method can be used in deahng with those problems of 

 nutrition which can only be solved by means of calorimetric 

 determination. 



Vitamins. 



Another large and important field of nutritional research of 

 which only the fringe can so far be said to have been explored is 

 that relating to the minute " accessory food substances " or 

 vitamins, which are known to play such an enormously important 

 part in the health of man and beast. One of the most important 

 discoveries of recent years has been that th^re are these unknown 

 and previously unsuspected constituents of food which are neces- 

 sary for the health of all animals and for the growth of young 

 animals. If these unknown substances are absent, conditions 

 of malnutrition arise in the full-grown animal, and the young 

 animal either ceases to grow or grows at a much lower rate than 

 it would do if the substances were present. Many feeding stuffs, 

 and especially the artificial foods, such as cakes, meals, &c., are 

 deficient in these substances, and when these are fed alone the 

 animal grows slowly and with lack of vigour. Work on this 

 subject is being carried out both at Aberdeen and at Cambridge,* 

 and while at this stage in a new line of investigaton it would be 

 unwise to dogmatise, it may be said that the results show that 

 many cases of slow growth, digestive troubles and other obscure 

 conditions of malnutrition may be due to a monotonous diet 

 deficient in vitamins, and further that the number, size and vigour 

 of the young at birth is to some extent influenced by the vitamin 

 content of the food of the mother. It is obvious that this may 

 prove to be a most profitable line of research and that results of 

 great economic value may be obtained. 



Some recent pig-feeding experiments at Cambridge are inter- 

 esting in their bearing on this point. It is well-known that rye- 

 fed pork is regarded with particular favour on the Continent, 

 but the practice is not adopted in this country, and the experi- 

 ments were instituted to determine, if possible, why rye-feeding 

 is not usually successful here. Put very briefly, the Cambridge 

 work showed that with young pigs rye was entirely unsatisfactory 

 when fed alone, but when supplemented by only a small handful 

 of grass per day it proved as wholesome as any other food. It 

 appears, therefore, that rye is deficient in a certain vitamin which 



* Vitamin experiments have also been carried out at the National 

 Institute for Research in Dairying at Reading, and are referred to in the 

 chapter on Dairying {see page 133). 



