Evaluation of the preference of mice on food intake - Preliminary study

One of the possible ways to improve the housing conditions of laboratory animals is to give animals opportunities to perform more species-specific behavioural repertoires through providing enrichment of their environment. Environmental enrichment is, by definition, any modification in the environment of the captive animals that seeks to enhance their physical and physiological well being by providing stimuli meeting the animals' species-specific needs. Food intake is of high concern as this should be promoting the expression of physical feeding behaviour and improves the welfare of the captive animals. The aim of the present study was to evaluate the preference of mice to receive their food from a feeding cup located inside the cage or from the classical food hopper located on the stainless steel wire lid of the cage. Twenty four male C57BL/6 mice, at the age of 5-7 weeks, originated from the breeding colony of the animal facility of the Foundation, were randomly divided into two groups. In group A (n=12) the food was supplied through the food hopper. In group Β (n=12) food was supplied through the feeding cup located in the front side of the cage, as well as through the classical food hopper on the wire lid of the cage. A statistically significant preference of the mice to use the feeding cup instead of the food hopper was noticed (p<0.05). A preference of animals to empty the feeding cup from the food pellets, eat them directly from the bedding and use the feeding cup as a shelter was also observed in all the cages of group B. Based on the above preliminary observations it is concluded that the placement of a feeding cup within the cage could improve the welfare of the animals housed in individual ventilated cages and trigger the expression of a more species-specific feeding behaviour.

Parasympathetic involvement in rapid meal-associated conditioned insulin secretion in the rat

Blood glucose and plasma insulin concentrations were measured in blood sampled via a cardiac catheter in freely moving rats. To obtain a rapid conditioned cephalic phase of insulin secretion, rats were habituated to one of two feeding schedules. Clock-activated opening of doors in front of the food hopper imposed a feeding schedule of either six meals per day or two meals per day. When the doors were opened in both conditions, insulin increased rapidly during the first minute of feeding in the middle of the light phase. However, when presented an empty food hopper immediately after door opening, only rats in the two meal per day condition showed raised insulin levels and not rats in the six meal per day condition. This response was abolished following pharmacological blockade of nicotinic receptors with hexamethonium and muscarinic receptors with atropine. The present study shows that rapid conditioned insulin secretion can be evoked within one minute by a meal-associated stimulus. These results further indicate that this conditioned insulin secretion is vagally mediated and that its occurrence is dependent on the nature of the feeding schedule.

Dominance among Captive Red-Winged Blackbirds (Agelaius Phoeniceus) in a Competitive/Cooperative Situation

8 pairs of male red-winged blackbirds were tested in an operant conditioning situation wherein both the response perch and food hopper were freely available to both members of a pair. It was observed that familiarization with a territory and epaulet visibility are not critical to maintenance of dominance in reproductively inactive birds. The potential usefulness of competitive/cooperative tasks for the study of dominance behavior is discussed.

Effects of Testosterone On Investigation of Stimulus Change By the Domestic Chick

Testosterone-treated chicks (T's) were more persistently disturbed than controls (C's), both by the introduction of a novel object into the home cage, and by its removal 24 hours later. This was shown, firstly, by delay in the first appearance of behaviour not directed to the novel object: the preliminaries to feeding (looking at the floor, visiting the food hopper) appeared later in T's, as did drowsiness. Secondly, behaviour was interrupted in T's by a return to investigation: in particular the first bout of feeding was markedly abbreviated and (after introduction of the object) was not followed as usual by stretching. None of these differences between T's and C's were present in undisturbed behaviour. It is probable that the development in T's of unusually protracted periods of sleep after removal of the novel object is another consequence of more prolonged disturbance in T's. Other evidence is cited suggesting that protracted sleep may be caused in this way. Increased persistence of attention, including an ability to return to a previous point of attention after a shift to a distracting stimulus, is known from other studies to be produced by testosterone in male chicks. Such an effect would explain the above findings. It is argued more speculatively that it may also underlie differences between T's and C's in the character of investigation, and not just its prolongation.