THE VARIATION IN TASTE THRESHOLDS OF 



RUMINANTS ASSOCIATED WITH 



SODIUM DEPLETION 



F. R. Bell 



Department of Physiology, Royal Veterinary College, 

 London, N.W.I., England 



At a recent symposium on the physiological and behavioural aspects of 

 taste, Tepperman (1961) discussed the inter-relationships of taste, meta- 

 bolism and nutrition. He paid due tribute to the pioneer studies in this 

 field of Richter who used the rat as the subject for experimentation 

 (Richter, 1943). Examples of self- regulatory processes are numerous in 

 certain deficiency states of ruminants, for example, Theiler, Green and 

 Du Toit (1924) showed that phosphorus deficient cattle have a preference 

 for bones (osteophagia). 1 should like to discuss a little further the 

 relationship between taste and biochemical status in ruminant herbivores, 

 with particular reference to sodium depletion. 



Herbivorous animals generally, and ruminants in particular, often exist 

 on a quite precarious mineral balance. This is because the vegetative 

 diets contain comparatively little sodium and a great deal of potassium. 

 The Na/K ratio of vegetable material often widens through the seasons 

 and more especially if potassium salts are included in chemical manures 

 (Dobson, Kay and McDonald, 1960). The ingestion of food relatively 

 deficient in sodium is reflected in the sodium plasma level which may be the 

 factor which produces the " drive " which causes wild ruminants to search 

 vast areas for salt licks (Russell and Duncan, 1956). I believe that in 

 Northern Sweden, the reindeer brought down to coastal regions appear 

 to relish long draughts of seawater. 



Firstly I should like to mention the results of experiments conducted to 

 ascertain the preference for sodium bicarbonate on a number of housed 

 goats. The care and management of the animals used in these experiments 

 and the technique of the two-choice preference test adopted are identical 

 with the description published earlier (Bell, 1959). Briefly, fluid was pro- 

 vided from two identical containers (3.7 1. bottles), each fluid container 

 having more than sufficient fluid to satisfy the animal for 24 hr. For the 

 test, one bottle was filled with a 1 per cent sodium bicarbonate solution in 

 tap water and the other with tap water. The amount of the two liquids 



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