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Title: Specific appetites in the domestic fowl
Author: Hughes, B. O.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1970
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The development and expression of specific appetites for calcium, sodium and thiamine in the fowl were studied. It was found that calcium -deprived chickens exhibited a preference for diets supplemented with calcium carbonate or calcium lactate. There was no immediate preference, but a group preference characteristically built up over a period of days, suggesting that learning plays a role in the development of this appetite. It is specifically for calcium, in that strontium, the element most closely related to calcium, is not selected. Experiments investigating the importance of visual and gustatory cues showed that selection could still occur when only visual, or only taste cues were available, though selection tended to be less efficient under these circumstances. No appetite could be demonstrated in the complete absence of these cues. A mildly unpleasant flavour such as calcium lactate may act as a helpful cue, but a more aversive taste, such asquinine, blocks the preference for calcium. The importance of hedonic responses is emphasised by the failure of deficient birds to select solutions of calcium salts, though they show a preference for a suspension of calcium carbonate, which is rather more palatable. Calcium deprivation leads to an increase in appetitive pecking behaviour when chickens are presented with a range of different stimuli in an open arena, although deprived and normal birds show similar preferential responses. The effects of deprivation could not be simulated in normal birds by the administration of parathyroid hormone, and it was'concluded that this hormone does not exert a direct effect on the behaviour. An experiment to measure the effects of deprivation on birds in an activity cage yielded ambiguous results. The importance of need reduction in the development of calcium preference was assessed. Exclusive access to a supplemented diet for as long as four days was necessary before a preference was noted. However, injection of a very small quantity of a calcium salt had a profound effect in delaying the development of the preference. Expression of the appetite could not be inhibited by administering drugs - either a depressant, like alcohol, or a true tranquillising agent. Taken as a whole, these results suggest that ingestion of calcium may exert its reinforcing action by means of a general effect on 'well- being', rather than upon some particular site of action, such as the skeletal system, or by means of some specific mechanism, such as anxiety reduction. The fowl differs from the rat in that novelty plays no part in the development of a specific appetite. A less detailed study was carried out on the effects of sodium and of thiamine deficiency. Both normal and sodium- deprived chickens avoid saline solutions. Deprived birds were indifferent to food supplemented with sodium chloride, and there was no avidity for sodium when a functional deficiency was induced by a non -dietary method. The only behavioural effect observed in these sodium - deprived chickens was an increase in appetitive pecking activity, similar to that seen in the calcium -deprived birds. It was concluded that the fowl, unlike the domestic rat and other mammals, does not exhibit a specific appetite for sodium. On the other hand, a specific appetite for a thiamine -supplemented diet was readily demonstrable after a deficient state had been induced by feeding a metabolic antagonist. The significance of these results was discussed in an evolutionary context, and they were related to the nutritional requirements of the fowl in a natural habitat.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available