Meal patterns of cats encountering variable food procurement cost

The physiological control of eating: signals, neurons, and networks

During the past 30 yr, investigating the physiology of eating behaviors has generated a truly vast literature. This is fueled in part by a dramatic increase in obesity and its comorbidities that has coincided with an ever increasing sophistication of genetically based manipulations. These techniques have produced results with a remarkable degree of cell specificity, particularly at the cell signaling level, and have played a lead role in advancing the field. However, putting these findings into a brain-wide context that connects physiological signals and neurons to behavior and somatic physiology requires a thorough consideration of neuronal connections: a field that has also seen an extraordinary technological revolution. Our goal is to present a comprehensive and balanced assessment of how physiological signals associated with energy homeostasis interact at many brain levels to control eating behaviors. A major theme is that these signals engage sets of interacting neural networks throughout the brain that are defined by specific neural connections. We begin by discussing some fundamental concepts, including ones that still engender vigorous debate, that provide the necessary frameworks for understanding how the brain controls meal initiation and termination. These include key word definitions, ATP availability as the pivotal regulated variable in energy homeostasis, neuropeptide signaling, homeostatic and hedonic eating, and meal structure. Within this context, we discuss network models of how key regions in the endbrain (or telencephalon), hypothalamus, hindbrain, medulla, vagus nerve, and spinal cord work together with the gastrointestinal tract to enable the complex motor events that permit animals to eat in diverse situations.

Domestic cats (Felis catus) prefer freely available food over food that requires effort

Contrafreeloading is the willingness of animals to work for food when equivalent food is freely available. This behavior is observed in laboratory, domesticated, and captive animals. However, previous research found that six laboratory cats failed to contrafreeload. We hypothesized that cats would contrafreeload in the home environment when given a choice between a food puzzle and a tray of similar size and shape. We also hypothesized that more active cats would be more likely to contrafreeload. We assessed the behavior of 17 neutered, indoor domestic cats (Felis catus) when presented with both a food puzzle and a tray across ten 30-min trials. Each cat wore an activity tracker, and all sessions were video recorded. Cats ate more food from the free feed tray than the puzzle (t (16) = 6.77, p < 0.001). Cats made more first choices to approach and eat from the tray. There was no relationship between activity and contrafreeloading, and there was no effect of sex, age, or previous food puzzle experience on contrafreeloading. Our results suggest that cats do not show strong tendencies to contrafreeload in the home environment, although some cats (N = 4) ate most food offered in the puzzle or showed weak contrafreeloading tendencies (N = 5). Eight cats did not contrafreeload. Cats who consumed more food from the puzzle, consumed more food in general, suggesting a relationship between hunger and effort. Further research is required to understand why domestic cats, unlike other tested species, do not show a strong preference to work for food.

Assessing Food Preferences in Dogs and Cats: A Review of the Current Methods

Food is a major aspect of pet care; therefore, ensuring that pet foods are not only healthful but attractive to companion animals and their owners is essential. The petfood market remains active and requires ongoing evaluation of the adaptation and efficiency of the new products. Palatability-foods' characteristics enticing animals and leading them to consumption-is therefore a key element to look at. Based on the type of information needed, different pet populations (expert or naïve) can be tested to access their preference and acceptance for different food products. Classical techniques are the one-bowl and two-bowl tests, but complementary (i.e., operant conditioning) and novel (i.e., exploratory behavior) approaches are available to gather more information on the evaluation of petfood palatability.

Stomach temperature telemetry reveals temporal patterns of foraging success in a free-ranging marine mammal

1. We studied feeding frequency in free-ranging grey seals using stomach temperature telemetry to test if previously reported sex differences in the diving, movement and diet were reflected in the temporal pattern of foraging success. 2. Data were retrieved from 21 of 32 grey seals from 1999 to 2001, totalling 343 days and 555 feeding events, with individual record length varying from 2 to 40 days (mean: 16.33 +/- 2.67 days/seal). 3. Seals fed on 57.8 +/- 6.46% of days sampled and had an average of 1.7 +/- 0.26 meals per day, but individual variability was apparent in the temporal distribution of feeding as evidenced by high coefficients of variation (coefficient of variation = 69.0%). 4. Bout analysis of non-feeding intervals of six grey seals suggests that feeding intervals of individuals were varied and probably reflect differences in prey availability. Grey seals tended to have many single feeding events with long periods separating each event, as would be expected for a large carnivore with a batch-reactor digestive system. 5. We found significant sex differences in the temporal distribution of feeding. The number of feeding events per day was greater in males (2.2 +/- 0.4 vs. 1.0 +/- 0.2), as was time associated with feeding per day (56.6 +/- 5.8 min vs. 43.9 +/- 9.4 min). 6. The number of feeding events varied with time of day with the least number occurring during dawn. Feeding event size differed significantly by time of day, with greater meal sizes during the dawn and the smallest meals during the night. 7. The length of time between meals increased with the size of the previous meal, and was significantly less in males (541.4 +/- 63.5 min) than in females (1092.6 +/- 169.9 min). 8. These results provide new insight into the basis of sex differences in diving and diet in this large size-dimorphic marine predator.

Who is in charge? Animal vs experimenter control

In the 1920s Curt Richter (1927) stated that the central problem for psychology was to discover the determinants of the initiation and termination of bouts of behavior. Ignoring this challenge, experimentation in animal psychology has been dominated by the session paradigm in which animals work in brief sessions for a resource of which they have been deprived. In this open economy, no behavioral strategy of the animal can meet its demand, and the beginnings and ends of bouts are controlled by the experimenter; thus, Richter's problem cannot be addressed. In contrast, in a free-feeding, closed economy, the animal controls the initiation and termination of feeding and can regulate its intake, and bout patterns can be observed. If the paradigm is modified to simulate a habitat where resources are distributed discontinuously and the animal must work to discover and procure access to a commodity before it can be used, behavioral strategies allowing the animal to regulate its intake while tending to maximize the ratio of benefits to costs are revealed. We offer an answer to Richter's question based on a cost/benefit analysis of feeding behavior in this foraging paradigm. We show that the time and energy costs of resource acquisition and resource consumption are powerful determinants of the pattern of resource use, and that they have different and independent effects. The former costs are reduced by reducing the frequency of initiating bouts, and the latter costs, by altering the rate and amount of consumption. Further, the time window of these relations is much longer than expected from analyses in the session paradigm. We conclude that the recurrent nature of behavior is due to the discontinuous distribution of resources rather than to cycles of physiological depletion and repletion, and that the determinants of bout initiation and termination lie in the economics of the allocation of time and effort to different resources and activities.