Experiential and genetic influences on learnt food aversions in Japanese quail selected for high or low levels of fearfulness.

Interactions between underlying fearfulness and social factors during the development of learnt food aversions was studied in two lines of Japanese quail selected for a long (LTI) or short (STI) duration of the tonic immobility response. Chicks of the LTI line have high inherent levels of fearfulness and chicks of the STI line have low levels of inherent fearfulness. Food aversions were conditioned by pairing blue coloration with the presence of Jackbean (which has mild post-ingestional toxic effects) in the animals feed. In each of 3 training trials, chicks were exposed, either individually or in same line groups of four, to coloured or uncoloured diets containing toxic Jackbean or non-toxic Fieldbean. After training the preferences of chicks for coloured or uncoloured non-toxic diets were assessed in a choice test. Analysis of time spent feeding and amount of feed consumed in the choice tests suggested three levels of interaction between the fear state of the chicks and their reactions to unfamiliar and/or toxic feed. First, when fear levels are high (individually tested LTI line chicks), food which resembles a previously experienced toxic diet is rejected. Second, when fear levels are intermediate (individually tested STI line chicks), animals prefer food which resembles a previously experienced non-toxic diet but do not totally reject food which resembles a previously experienced toxic diet. Third, when fear levels are low (group testing), previously experience of toxic or non-toxic diets has limited effects on food choice. Animals show a preference for diets with a form similar to that which they were fed during early life but this preference is to some degree modulated by more recent feeding experiences.