Behaviour Components in the Feeding of Wild and Laboratory Rats

Abstract

Feeding behaviour has been studied in rats (Rattus norvegicus Berkenhout) kept in small cages in which a choice of foods was offered. Most of the rats were wild, but some albinos were used for comparison. The main intention of the experiments was to elucidate the component activities which make up feeding behaviour; but some observations on food preferences were made. When offered minced liver, wheat grains, flour and sugar, rats usually ate some of each food; sugar was eaten least, and sometimes little of e i t h e r flour or wheat was taken. When offered the alternative of wheat mixed either with cod liver oil or aniseed oil, as against wheat mixed with arachis oil, consumption was almost confined to the arachis oil mixture. This was true even when, as nestlings, the rats had been given only the distasteful mixture to eat. Both wild and albino rats show very marked exploratory and sampling behaviour during feeding. Evidence is presented that this is a pattern in its own right, and not merely appetitive. Its function is to make possible the rapid learning of topography, and especially the whereabouts of food, water and shelter. Sampling is also important in enabling rats to associate particular physiological actions, whether nutrient or toxic, with different foods. Exploration and sampling occur even when the situation and the foods are familiar, and regardless of age or sex. Continued sampling makes possible regular reinforcement of learned preferences. It also enables rats to change rapidly from a familiar but distasteful food to an unfamiliar but palatable one. Sampling is not stopped by 'satiation', but is released by it. In wild rats, but not albinos, there is highly developed flight and avoidance behaviour. This tends to reduce the dangers of exploratory behaviour. Both wild and tame rats tend to feed in cover when this is practicable. This has indirect social effects, since one rat may rob another in the nest. Social influences on feeding are only incidental. Often they are a product of associative learning. There is no parental guidance of young, nor imitation by young of adults. Displacement grooming was seen when hungry rats were deterred from feeding by the unfamiliarity of the situation; and in other frustrating circumstances. It is concluded that much of the feeding behaviour of wild rats can be interpreted as a resultant of the opposed effects of exploration and sampling on the one hand, and flight and avoidance on the other.

Signal-directed behavior in the rat: Interactions between the nature of the CS and the nature of the UCS

“…One explanation for this anomaly may lie in the ecological relevance of the cues possessed by a retractable lever CS when heat or food is used as the DCS. The small, manipulable nature of the lever CS has a relevance to feeding, since rats regularly approach and investigate small edible and inedible objects when feeding (Barnett, 1956). However, there is no reason to suppose that a rat that is seeking warmth should approach and investigate a small metal object such as a retractable lever.…”

“…For instance, rats normally approach and investigate small, manipulable objects when feeding; the retractable levers used as appetitive CSs in many autoshaping studies are also small, manipulable objects, which, prima facie, possess features appropriate for releasing this investigative foraging activity (cf. Barnett, 1956;Davey, 1989;Davey & Cleland, 1984). Rats also approach and contact a conspecific CS for food, and this appears to be related to the fact that rats are social feeders that tend to approach other rats when feeding (Timberlake, 1983;Timberlake & Grant, 1975).…”

Hypothalamic Agrp Neurons Drive Stereotypic Behaviors beyond Feeding

“…Food deprivation also exacerbated grooming behavior ( Figure 1E). In such conditions, grooming has been considered a displacement behavior (Barnett, 1956), a substitute of consummatory eating. Re-feeding acutely attenuated grooming ( Figure 1E), reinforcing that displacement behaviors, such as grooming, manifest when animals lack the consummatory response.…”

Diet sampling by wild Norway rats offered several unfamiliar foods

“…The important implication of the present data, when considered together withthose ofBamett (1956( ) andRozin (1969, is thatthere is no basisfor asserting that rats have evolved a strategy of eating one unfamiliar food at a time. Without evidence of such an adaptation, it is not parsimonious to assert its existence (Williams, 1966).…”