Feeding Sessions Research Articles

The influence of visual and chemical stimuli from codGadus morhuaon the distribution of two-spotted gobyGobiusculus flavescens(Fabricius)

Abstract Detection of a potential predation risk and its influence on patch choice was measured by examining the spatial distribution of 10 two-spotted gobies Gobiusculus flavescens (FABRICIUS) between two feeders, at one of which the presence of a predator was introduced either visually, chemically or both visually and chemically. Without predation influence the gobies were distributed according to the Ideal Free Distribution (IFD). However, as the chemical and I or visual stimulus from a predator cod (Gadus morhua L.) was introduced together with the food at one of the feeding sites, the gobies avoided the affected site. The avoidance persisted during feeding sessions for 1 or 2 days after the introduction. Although image had the most pronounced effect at the time of introduction, odor had a stronger effect on the gobies persistence in avoiding the affected site. Introduction of odor from an injured conspecific (alarm substance) at one of the feeding sites, had no significant influence on the gobies' distribution.

Density-dependent predation by skunks using olfactory search images.

The formation of search images can create density-dependent predation. Predators have been shown to form search images when searching for many small prey items in one feeding session. This paper reports experiments that test whether striped skunks can form olfactory search images in other situations: when prey are found over several days, when prey are large, and when prey are found in certain habitats. Striped skunks were raised in captivity, and their reaction distance to food was measured outside in a natural grassy area. In experiment 1 skunks were offered many small food items for several days in a row. From one day to the next, skunks initially detected food from further away, they increased detection distance faster and their maximum detection distance increased - i.e., they formed olfactory search images faster and stronger from one day to the next. In experiment 2 skunks formed search images over several days when finding only one large food item per day. In experiment 3 skunks lost olfactory search images when they entered habitats in which they had previously searched for another type of food. These long-term search images magnify the effects of short-term search images, extend the effects of short- term search image to longer time spans, and affect different species from short-term search images.

A feeding scale for research and clinical practice to assess mother—infant interactions in the first three years of life

The Feeding Scale provides a reliable rating of mother-infant/toddler interactions during a 20-minute feeding in a laboratory setting. The scale consists of 46 mother and infant behaviors, which are rated at the end of the feeding session. Observations of mother—infant interactions during two feedings separated by 2 weeks showed considerable stability. Five subscale scores are derived (1) Dyadic Reciprocity, (2) Dyadic Conflict, (3) Talk and Distraction, (4) Struggle for Control, and (5) Maternal Non-Contingency, Predictive validity of the Feeding Scale has been demonstrated and it discriminates between infants with and without feeding disorders as well as three diagnostic categories of feeding-disordered infants. The Feeding Scale can be used with infants and toddlers ranging in age from 1 month to 3 years. © 1997 Michigan Association for Infant Mental Health

Discrimination of circadian phase in intact and suprachiasmatic nuclei-ablated rats

This study examined whether the circadian system of rats can serve as a consulted clock for discriminating time of day. Food restricted rats housed in activity wheels were trained to lever press for food in a two-lever T-maze in which the left arm was correct in a morning feeding session, and the right arm in an afternoon session (7 h interval). All six rats learned the task (discrimination ratios > chance on 85–95% of sessions) and exhibited anticipatory wheel running prior to most sessions. Performance was not disrupted by inverting the LD cycle or by omitting 1–3 sessions, indicating that learning was not dependent on light-dark cues, alternation strategies, or physiological states associated with intermeal interval. Five of six additional rats with ablations of the suprachiasmatic nucleus light-entrainable pacemaker acquired the discrimination, indicating that time-of-day cues can be provided by another circadian pacemaker (likely food-entrainable). The results provide the first clear evidence that the circadian system in a mammal can function as a consulted clock that provides discriminative time cues for cognitive processes subserving behavioral plasticity.

Fallow deer tactic to compete over food with red deer

Small ungulates may compete with larger species through higher mobility, greater aggressiveness, and/or by larger group sizes. We observed a herd of approximately 100 red deer (Cervus elaphus) and 130 fallow deer (Dama dama) at the Žehušice Deer Park during supplemental feeding to determine whether fallow deer can displace red deer at feeding sites and to describe strategies used for displacement. Data were analyzed during the antlered period (AP) when males of both species had hard antlers and the cast period (CP) when all red deer stags had cast antlers, but fallow bucks were still in a hard antler. We conducted 41 observation sessions, 29 during the AP and 12 during the CP. In both periods red deer were more numerous than fallow deer at the feeding sites. Fallow bucks initially waited until red deer arrived at the feeding site, after which they attacked any red deer. Fallow bucks were more aggressive than red deer stags or hinds. When stags retaliated, the bucks turned their attacks toward hinds. During feeding sessions, attacks against hinds intensified, while bucks avoided encounters with stags. As a result, in most cases (90%), red deer vacated the feeding site before the supplementary food was depleted. In contrast, fallow does not compete with the larger red deer and selected other sources of food in the park. © 1996 Wiley-Liss, Inc.

Social interactions and the distribution of food among one-sea-winter Atlantic salmon ( Salmo salar) in a sea-cage

In order to test whether the amount of food obtained by individual one-sea-winter Atlantic salmon was related to social status, the feeding interactions of 19 individually marked Atlantic salmon in a sea cage were monitored by underwater video (fish competed for single food pellets presented at regular intervals). Food was distributed unevenly among fish; no significant relationship was found between food intake and either weight or gender. More successful fish fed earlier in a feeding session than their companions, and smaller fish avoided competitors when approaching pellets. There was a positive relationship between food intake and frequency of being beaten to pellets, but no relationship between food intake and proportion of feeding attempts in which a fish was beaten. This suggests that fish of a similar status were scrambling for food. Previous studies have shown a negative relationship between the coefficient of variation in daily food intake and total food intake, but did not control for fish size. Here we found the same relationship after controlling for fish size, showing that more successful fish had less variation in their day to day consumption than did less successful conspecifics. These data suggest that, in order to prevent food monopolisation by few individuals, the food should be presented so that it is unpredictable in time and space.

“PUSHY” BEHAVIOR IN A WILD DOLPHIN FEEDING PROGRAM AT TANGALOOMA, AUSTRALIA

AbstractA program where wild bottlenose dolphins (Tursiops truncatus) are fed by tourists in shallow water adjacent to a wharf has been established at Tangalooma, Queensland, Australia. Up to nine dolphins attend the nightly feedings, and between 60 and 80 resort guests are permitted to hand feed these dolphins each night. Since this program began in 1992, the dolphins have increased in confidence and have started, at times, to make forceful contact with guests who enter the water to feed them. This paper categorizes such behavior as “pushy” and reports on a study which quantifies the “pushiness” of the dolphins which feed at Tangalooma. The study examines ecological variables which may determine how pushy the dolphins are at different feeding sessions. The number of dolphins attending a particular feeding significantly increases the pushiness. In addition, the presence of adult males at a feeding is likely to increase pushing. Tidal state also influences how pushy the dolphins are. At low tide, when the dolphins’mobility is restricted by the water depth, they are less likely to be pushy. Given the problems experienced in a number of other situations where wild animals are fed by humans, it is important to monitor carefully the escalation of pushy behavior in this dolphin feeding program, as it may be a precursor to more aggressive actions on the part of the dolphins.

Anticipation of conflict by chimpanzees

Captive chimpanzees appear to anticipate the occurrence of conflict during feeding by grooming and being in proximity at increased rates during the hour prior to feeding. The effect is more marked when food is clumped than when it is dispersed, suggesting that the proximate cause is the anticipation of increased levels of competition. Chimpanzees did not choose high ranking individuals more often as prefeed grooming partners; rather, they preferred to associate with their normal grooming partners (as reflected in post-feed grooming preferences) and close kin. A strong correlation between prefeed association patterns and spatial proximity during clumped feeding sessions suggests that their main concern is to be allowed to feed near individuals who are able to monopolize food sources.

Dopaminergic correlates of motivated behavior: importance of drive

In vivo brain microdialysis was used to monitor changes in dopamine (DA) release in the nucleus accumbens (NAc) during anticipatory and consummatory components of feeding behavior. During 10 daily training sessions, rats were first confined to one compartment of a testing chamber for 10 minutes. During this period (anticipatory phase) they were prevented from gaining access to a highly palatable liquid meal by a wire mesh screen. The screen was then removed and the animals were permitted to consume the meal for 20 min (consummatory phase). On removal of the screen, the latency to begin drinking decreased and the amount consumed increased as a function of days of training, both measures reaching asymptotic levels by day 7. Trained animals were implanted with dialysis probes in the NAc on day 10, and on day 12 DA release was monitored during the feeding session. Compared to controls, trained animals failed to show significantly greater increases in accumbal DA release during the anticipatory phase, all groups showing small (approximately 10%) increases on being placed in the test chamber. In contrast, compared to controls, DA release increased significantly in the NAc during consumption of the palatable meal. The magnitude of this increase was significantly enhanced (30% vs 71% peak increase) in animals that were 20 hr food deprived at the time of testing. The latter animals also showed a statistically significant increase (24%) in DA release during the anticipatory phase. A subsequent experiment in which consumption of the palatable liquid was limited to 5 ml in deprived and nondeprived animals indicated that only part of the deprivation-induced potentiation of accumbal DA release could be attributed to the larger volume consumed by the deprived animals. That is, the same volume and rate of consumption of a small amount of the liquid diet produced a significantly greater increase in accumbal DA release in deprived than in nondeprived animals (42% vs 23% peak increase). Feeding-induced increases in accumbal DA release were not due to postingestional factors as direct injections of the liquid diet into the stomach by gavage failed to produce this effect. The results of these experiments indicate (1) that consummatory rather than anticipatory aspects of feeding are robustly associated with increases in DA release in the NAc, and (2) that motivational state can influence the magnitude of the neurochemical events that are associated with goal-directed behaviors.

The objective rating of oral-motor functions during feeding

The Schedule for Oral Motor Assessment (SOMA) was developed to record oral-motor skills objectively in infants between ages 8 and 24 months postnatal. Its aim is to identify areas of dysfunction that could contribute to feeding difficulties. The procedure takes approximately 20 min to administer, and is intended to be rated largely from a videorecording of a structured feeding session. A series of foodstuffs of varying textures, including liquids, is presented to the child in a standardized manner. Oral-motor skills are evaluated in terms of discrete oral-motor movements. The schedule distinguishes these from skills at more aggregated levels of functioning such as jaw, lip, and tongue control. A total of 127 children have been studied with the instrument, including normal healthy infants and samples with nonorganic failure to thrive, and cerebral palsy. Interrater and test-retest reliabilities were determined on a subset of 10 infants who each took part in three trials rated by 2 therapists. Excellent levels of interrater reliability (kappa > 0.75) were obtained for the presence/absence of 69% of discrete oral-motor behaviors. Test-retest reliability was similarly excellent for 85% of ratable behaviors. For the first time an assessment of oral-motor functioning has been shown to have adequate reliability for children aged 8-24 months. The validation of the SOMA on a large sample of normally developing infants and its application to clinical groups is presented in an accompanying paper [1].

Does the histaminergic system mediate bombesin/GRP-induced suppression of food intake?

Bombesin (BN) and its mammalian homologue, gastrin-releasing peptide (GRP), are potent satiety agents and have been implicated in the physiological regulation of food intake. The mechanism(s) of action of this effect remains unclear. There is a functional and anatomic overlap between histamine and BN in relationship to feeding, which led us to hypothesize that BN may mediate its satiety effects through activation of the histaminergic system. To assess this contention, we examined the effects of R-alpha-methylhistamine (alpha-MH) and Imetit, selective H3-receptor agonists that inhibit the release and synthesis of histamine, on BN- or cholecystokinin (CCK)-induced satiety. In this report we present the first evidence for the role of histamine H3 receptors in the mediation of BN-elicited satiety. During the first hour of the 4-h daily feeding session, BN reduced food intake by > 50% relative to the control condition; this suppression was blocked by prior treatment with the H3-receptor agonist, alpha-MH. This blockade of BN-induced satiety was dose related and selective to BN as alpha-MH failed to attenuate sulfated CCK-8-induced satiety. When alpha-MH was administered alone, it failed to significantly affect food intake. The specificity of this effect was further supported by the demonstration that another H3 agonist, Imetit, was also able to block the feeding-suppressant effects of BN. Furthermore, thioperamide, an H3-receptor antagonist, blocked these effects of Imetit.(ABSTRACT TRUNCATED AT 250 WORDS)

Facilitation of defense reactions during the consumption of food in snails: the participation of glucose and gastrin/cholecystokinin-like peptide.

The molecular-cellular mechanisms of the interrelationships between the alimentary and defense behavior of snails were investigated. The clarity of manifestation of defense reactions at various stages of the satisfaction of alimentary need was studied. It was found that the defense reactions were attenuated in starved molluscs, whereas after a 20-minute feeding session the facilitation of generalized defense reactions takes place, the clarity of manifestation of which depends on the duration of food deprivation. It was demonstrated that an increase in the level of glucose in the hemolymph of the starved molluscs to the level present in the hemolymph during a meal (1.6-2.0 mM), as well as the administration of 20-30 ng of analogs of gastrointestinal peptides (pentagastrin or cholecystokinin octapeptide, CCK-8) elicits the facilitation of generalized defense reactions similar to that found during the feeding of the snails. The directionality of the changes in the activity of the L-RPl1 neurons during the application of carrot juice to the lip of semi-intact preparations of starved snails depended on the presence of glucose in the solution bathing the central nervous system. Similar glucose-dependant changes were found after the application of CCK-8 to the CNS of starved snails, but not of FMRFamide, whereas the isolated application of glucose did not exhibit such an effect. It was found that the L-RPl1 neurons were the most sensitive to the change in the concentration of glucose and CCK-8 in the perfusate. The adaptive significance of the dependance of the clarity of manifestation of defense reactions on the level of alimentary need of the snails and the participation of glucose and gastrin or cholecystokinin-like peptide in these processes are discussed.

Suckling-induced attenuation of plasma cortisol concentrations in postpartum lactating women.

The effect of suckling on serum cortisol concentrations was assessed in postpartum lactating women studied during serial breast feeding sessions 1-24 weeks postpartum. The mean +/- SD serum cortisol concentration at 15 min after the start of nursing, 9.8 +/- 3.89 micrograms/dl, was significantly lower, P = 0.001, than prior to the start of nursing, 13.2 +/- 5.92 micrograms/dl. The decline in the serum cortisol concentrations in the breast feeding women was not due entirely to the normal metabolism of the hormone or the normal circadian variation in cortisol secretion. These studies complement and expand upon a recent report [3] of a significant decrease in plasma adrenocorticotrophic hormone in breast feeding women studied one week postpartum. The neuroendocrine mechanisms responsible for this effect in women have yet to be defined.

Persistence of Sham feeding after real-fed gastric loads in rats

Esophagostomized rats were permitted to “real-feed” a glucose solution (Experiment 1) or milk (Experiment 2), by receiving intragastric (IG) infusions concurrent with sham feeding. This was done for the first part of the feeding session; then the IG infusions were discontinued so that subsequent ingestion was sham. When such infusions stopped after 80% of real-meal volume had been delivered, they had no measurable effect on subsequent oral ingestion: sham feeding persisted as if nothing had been delivered IG. Therefore, the onset of postingestive satiety, at least in experienced sham-feeding rats, is all-or-none or close to it: if the IG loads are even slightly short of what is required to abolish sham feeding, then they do not affect sham feeding at all. This is so even if the postingestive events occur within their normal behavioral context.

Revegetated Sand Mining Areas, Swamp Wallabies and Remote Sensing: North Stradbroke Island, Queensland

Mining of mineral sands has taken place on North Stradbroke Island for over 40 years. Revegetation of mined areas creates a mosaic of seral classes. For a mine site in the northwest of the island, Landsat Thematic Mapper data were used successfully to map the distribution of seven seral classes resulting from mining rehabilitation. Faecal pellet counts were used to assess usage of these areas and surrounding natural forest by swamp wallabies, Wallabia bicolor. Results indicated that revegetated sites from 2 to 4 years in age were heavily used by wallabies. Older revegetated sites, dominated by senile Acacia cunninghamii, and offering little or no forage, were avoided. Swamp wallabies used revegetated sites for night‐time feeding sessions and rested, during the day, in surrounding eucalypt forest.

Maternal education and child feeding practices in rural Bangladesh

This study in rural lowland Bangladesh used spot and event observations from 185 children aged 4–27 months in order to examine whether child feeding practices differed with mother's education and with household education. Each child and his/her caretakers were observed for a mean of 20 hr over 6 months from February to July 1986. Only 25% of mothers and 51% of fathers had had any formal education. Exploratory partial correlations and stepwise multiple regression analyses revealed significant behavioral differences with both maternal and household measures of education while controlling for wealth. Caretakers in families with education were found to feed the children more frequently, with fresher food, and in cleaner, more protected places. They did not allow their children to eat food intended for someone else as often, and were more observant when their children's food dropped during the feeding. These caretakers also used more cups and bottles for feedings, breastfed their children less frequently, and their mothers terminated the breastfeedings more often. These behaviors suggested a shift from less attentive feeding practices and less frequent feedings to more frequent feedings in which the caretaker took more control of the child's feeding sessions. They also suggest a commitment to more labor-intensive child care. These associations between education and child feeding practices are mechanisms through which maternal education may improve child health and growth. They suggest the need for promoting more formal and nonformal education.

Filial imprinting in blackbird nestlings, Turdus merula, after only one feeding session

Filial imprinting in blackbird nestlings, Turdus merula, after only one feeding session

Seed dispersal and vegetation dynamics at a cock-of-the-rock's lek in the tropical forest of French Guiana

The Guianan cock-of-the-rock (Rupicola rupicola (Linnaeus) 1766) is a large (140-230 g) lek-breeding bird of the Neotropical family Cotingidae. Adult males and females are mainly, if not exclusively, frugivorous (Erard et al. 1989, Schuchmann 1984, Snow 1971). Adult males are densely clustered on classical leks, where they defend ground display courts or adjacent perches (Trail 1985). Numerous seeds are defecated or regurgitated on the lek, after short feeding sessions at nearby fruiting trees. In order to measure the influence of seed dispersal by Rupicola rupicola on tropical forest regeneration and succession, this preliminary study compares the floristic composition of dispersed seeds, seedlings and larger plants found on the lek with (a) fruit preferences found in a previous study, (b) the floristic composition of the high primary forest surrounding the lek, and (c) the low vegetation of another granitic outcrop. The research was conducted in French Guiana at the Nouragues biological station (40 03' N, 52? 42' W; an undisturbed primary forest site described in Erard et al. 1989, Julliot & Sabatier in press), from 10 October to 15 December 1990 (dry season). As in Gilliard's study (1962), the lek was situated on the ridge of a steep granite hill; the vegetation consisted of small trees 8-15 m and medium trees 15-18 m high, with a dense understorey of young saplings. Numerous perches were worn, showing long-term use by adult males. Twenty-one species of seeds were collected under males' perches on the 230 m2 lek, and two categories were used to describe the vegetation: seedlings and larger plants. Among larger plants, 545 saplings of 45 species, and 82 trees of 17 species

Effects of preadaptation to restricted feeding and cimetidine treatment on gastric mucosal injury and wheel running during exposure to activity-stress

The relationship between gastric injury and wheel running was examined during an activity-stress (A-S) experiment. In Experiment 1, rats were preadapted to a 1-h restricted feeding schedule for either 0, 15, 25 or 35 days prior to entering activity wheels. All rats preadapted to the 1-h feeding schedule had significantly less gastric damage than rats without any preadaptation experience. Survival of A-S was related to the length of preadaptation experience. Regardless of preadaptation experience, rats increased daily running with the greatest increase occurring during the 6-h period preceding the feeding hour. In Experiment 2, rats were injected twice daily with cimetidine (100 mg, ip) or vehicle during the 6-h preceding the feeding session. Rats treated with cimetidine had less mucosal injury but had no increased survival when compared to rats injected with the vehicle. Cimetidine treated rats had essentially the same running pattern as controls. These results demonstrated that the process of mucosal injury did not stimulate excessive wheel running. The data also suggest that mucosal injury is not related to survival in A-S rats.

Wolf spider feeding strategies: optimality of prey consumption in Pardosa hortensis.

Feeding behaviour of the wolf spider Pardosa hortensis Thorell (Araneae, Lycosidae) was studied in the laboratory. Characteristics of feeding were measured while prey availability was increased and the results were compared with the predictions of three models: the marginal value theorem (MVT), gut limitation theory (GLT) and the digestion rate limitation model (DRL). As a result of more frequent encounters with prey, the wolf spiders were able to modify their feeding behaviour so that their net energy intake rate increased substantially. Handling time decreased by 30%, and consumption rate increased by 40%. Partial consumption of prey did not occur until the spiders became nearly satiated. This indicated that spiders did not reach the optimum predicted by MVT. The most plausible mechanism for the increased efficiency was prey-stimulated digestive enzyme production as suggested in DRL. The predictions of GLT were not applicable for most of the feeding session, though gut satiation had an influence on the final stages of feeding. P. hortensis seemed to apply a "responsive but cautious" strategy: (i) spiders improved feeding efficiency on entering the higher quality habitat, but (ii) feeding times appeared to be sub-optimal and (iii) spiders were also willing to continue feeding when, as they approached satiation, the previously high efficiency could not be maintained. Such feeding behaviour optimizes long-term energy intake when food is scarce and unpredictable, which corresponds well with the known degree of natural food limitation of these animals.