Increased synthesis of prolactin and growth hormone during incubation in the pituitary of broody Nagoya hens

Synthesis and release rates of prolactin and growth hormone (GH) in the anterior pituitary of laying and incubating broody chickens (Nagoya breed) were determined by a disc electrophoretic technique after in vitro incubation of anterior pituitaries with a labeled amino acid. Prolactin synthesis and release were two-fold higher in incubating than in laying hens, resulting in twofold increase in the concentration of prolactin in the gland. GH synthesis was three-fold higher in incubating than in laying hens but GH release was not affected by the incubation. GH concentration in the pituitary gland also increased in incubating hens. It is suggested that these changes in hormone synthesis, release, and concentrations are related to nesting behaviour and nutritional condition of incubating hens.     

Degree of social contact affects the emission of food calls in the common marmoset (Callithrix jacchus)

The aim of this study was to investigate whether the emission of food calls in common marmosets (Callithrix jacchus) is influenced by different social contexts. Food calls are emitted by this species only in the presence of preferred food. If these calls have any communicative function, it may be that individuals produce food calls in order to call family mates toward the food source. If this is the case, the number of calls produced should vary in accordance with the number of family mates present at the moment of the discovery of the food, i.e., the fewer family mates nearby, the more food calls are emitted. This hypothesis was tested with five pairs of common marmosets, by recording the number of food calls emitted in four experimental conditions: 1). isolation: completely isolated from the family mates; 2). visual isolation: separated by a wooden panel from the family mates; 3). visual contact: separated by a wire-mesh from the family mates; and 4). physical interaction: together with the family mates. The results show that the proportion of intervals during which food calls were produced by the pairs was significantly different in the four experimental conditions. It decreased from the isolation and visual isolation condition, through the visual contact condition, reaching the lowest value in the physical interaction condition. The variation observed in the proportion of intervals during which food calls were emitted, in relation to different social contexts, is an indication in favor of the communicative function of this vocalization.     

Changes in endocrinological parameters and production performances in Turkey hens (Meleagris gallopavo) submitted to different broody management programs

Occurrence of broodiness, egg production, feed consumption index and changes in the LH and prolactin levels were compared for turkey hens raised under 3 broody management programs. All hens (n = 60 per group) were regularly ejected from the nest (basic treatment). Moreover, one group of hens was also rotated weekly (partial treatment), while in the third group (full treatment) hens showing broody symptoms were also identified daily and isolated for 24 hours. The percentage of hens which were identified as broody at least once was similar under the 3 programs (30%), although the use of the full and partial programs were more effective in inducing the disruption and/or preventing further expression of broody behavior. Plasma LH concentrations decreased progressively throughout the reproductive cycle under the 3 treatments. Maximum plasma concentrations of prolactin were measured between the 5(th) and the 10(th) weeks of production; higher concentrations of prolactin were maintained for a longer period under the full treatment, while a lower amplitude rise in plasma prolactin concentrations was observed in the hens submitted to the partial treatment. The egg production and feed consumption indices were lower and higher, respectively, under the full treatment than the basic treatment and partial treatments. We conclude that management programs need to be carefully evaluated under commercial conditions not only with respect to broodiness expression but also to egg production.     

Endocrinological and behavioural effects of p-chlorophenylalanine (PCPA) oral administration to broody turkey hens (Meleagris gallopavo)

Changes in plasma levels of prolactin and LH, feed intake, water consumption, behavioural pattern and ovarian activity were recorded after oral administration of PCPA to broody turkey hens. A decrease in prolactin concentration was measured, from day 3, in 3 out of the 5 birds treated with 100 mg PCPA/kg body weight (BW) for 3 consecutive days. In these hens, broodiness was disrupted on day 6 and feeding activity subsequently increased to levels of photorefractory hens. Neither LH concentrations nor ovarian activity were affected after treatment with PCPA. Moreover, PCPA treatment was ineffective at a 50 mg/kg BW dose. These results confirm that a serotoninergic mechanism is probably involved in prolactin release and moreover suggest that prolactin is implicated in maintaining broody behaviour. However, the reductions in the plasma concentration of prolactin induced by PCPA were not sufficient to restore the hypothalamic-hypophyseal-ovarian axis to a physiological status characteristic of the laying hen. Therefore, PCPA does not appear to be a useful method of treating broodiness in commercial turkey hens.     

Toque macaque food calls: Semantic communication concerning food distribution in the environment

Upon the rare occasions that wild toque macaques (Macaca sinica) discover a large quantity of food in their natural forest environment they give distinctive calls. The durations of feeding bouts and the rates of feeding are significantly greater at sites where food calls are given than at sites of the same food types where no foods call are given. The calls designate a new location of a large quantity of any one of several food types. Dispersed group members hearing the call immediately run to the site of the call and feed there. I conclude that food calls are semantic signals (or symbols) that evoke the same response (rapid direct approach) as seeing the external referent of the calls (a source of abundant food) itself would. Food calls convey information about the presence of an edible food source, its quantity and location in the environment. As a general type, food calls appear to be related to, but are distinct from, contact calls which function to mintain group cohesion.     

Maternal food calling in domestic hens: influence of feeding context

The aim of this study was to understand the relationship between production of food calls by maternal hens and food context. In a series of experiments with broody hens, we manipulated quality of items, quantity of food, food experience and dispersion of food items. We measured the frequency of food calling during standardized tests. Our results show that all the variables tested had significant effects on food calling. These results present some similarities and some discrepancies with previous reports on food calling by cockerels.     

Evidence that nitric oxide modulates food intake in mice

Nitric oxide (NO) may be an intercellular modulator within the central nervous system. L-arginine, which results in NO synthesis, increased food intake in mice while the inhibitor of NO synthesis, L-NG-nitro arginine (L-NO Arg) inhibited food intake in food deprived mice. L-arginine, but not D-arginine, partially reversed the inhibitory effect of L-NO Arg on food intake. These findings suggest the possibility that NO may be a physiological modulator of food intake and that the possibility of exploring the utility of L-NO arg in the treatment of obesity should be explored.     

Social learning influences the preferences of domestic hens for novel food

It has been argued that social learning helps animals either avoid noxious substances or identify food items, but evidence suggests that avian social learning is fundamentally different from that of mammals. In two experiments, we investigated whether the preferences of domestic hens, Gallus g. domesticus, for novel food were influenced by observing the feeding behaviour of conspecifics. In experiment 1, we attempted to confirm that birds can develop socially learnt aversions to unpalatable foods. Despite demonstrators showing a highly visible ‘disgust reaction’ after eating unpalatable coloured food, observers did not develop aversions to similarly coloured food. In experiment 2, we aimed to determine whether preferences for palatable food were socially learnt, and whether the extent of a demonstrator's preference for novel food affected the magnitude of the observer's socially learned preference. Demonstrators ate coloured food of standard or high palatability, or did not peck food at all. When the demonstrators pecked more frequently or fed more quickly from the food, the observers consumed a greater proportion of food of the same colour; however, this was only when the food was red, not green. We argue this indicates an unlearned aversion to red food, overcome by social learning of the food being highly palatable. The results provide no evidence that adult hens learn aversions through observing disgust reactions, but show that hens are sensitive to the extent of demonstrator preferences for palatable food. The data do not support the hypothesis that avian social learning is fundamentally different from that of mammals. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Acute decrease in vitellogenin synthesis by deprivation of food and water in laying hens

Vitellogenin synthesis during a decrease in egg production caused by depriving food and water was investigated in Single Comb White Leghorn hens. They were transferred from long days of 14L: 10D to short days of 10L: 14D 5 days before food and water deprivation. Then food was deprived for 5 days and water for 2 days. The body weight was markedly decreased by the treatment and reached its minimum after 5 days. The egg production rate which was 85% before the treatment was nil after 4 days. On day 3 the circulating vitellogenin concentrations, measured by a newly established RIA system, was markedly decreased by deprivation of food and water to 22% of the pretreatment level. The concentrations remained less than 10% during cessation of egg laying. Serum luteinizing hormone (LH) and progesterone concentrations decreased gradually, but estradiol 17 beta (E2) decreased abruptly. This acute decrease closely coincided with the decrease in egg production and the weight of the oviduct and ovary. These concentrations were gradually increased after day 16 and returned to the normal level after 46 days. Circulating thyroxine (T4) and triiodothyronine (T3) concentrations gradually increased from the beginning of the change in the day length and peaked on day 7 or 9, whereas reverse (r)T3 rapidly increased. The concentrations again decreased at the beginning of molting which occurred later due to the deprivation of food and water. Thus, these results demonstrated for the first time that the decrease in egg production induced by deprivation of food and water closely related to the decrease in vitellogenin synthesis as well as gonadal and pituitary functions. Further, recovery of egg production was coupled with the increase in the ovary and oviduct weight, and circulating LH, E2, progesterone, and vitellogenin.     

Playbacks of food-associated calls attract chimpanzees towards known food patches in a captive setting

Food-associated calls have received much research attention due to their potential to refer to discovered food in a word-like manner. Studies have found that in many species, food-associated calls attract receivers to the food patch, suggesting these calls play roles in food sharing, cooperation and competition. Additionally, in various species, these calls play a role that has received much less attention: mediating social interactions among foragers that are already nearby or within the food patch, independently of whether they attract outside foragers. In order to increase understanding of the function of the chimpanzee (Pan troglodytes) food-associated rough grunt, we conducted captive playback studies testing whether rough grunt playbacks attract, repel or have no effect on the proximity of foragers already familiarized with the presence of food. We tested how acoustic playbacks of rough grunts (or control calls) from one of two known, identical feeding sites affected receivers’ approach and feeding behaviors. More often than expected, participants first approached the feeding site from which rough grunts, but not control calls, were broadcast. However, neither condition increased the likelihood that participants fed first from a given site. Our results support the hypothesis that rough grunts elicit an approach response in receivers, while providing no evidence that they repel. In addition, our study provides evidence that receivers may approach rough grunts even if they do not intend to feed. We discuss the information rough grunts may convey to receivers beyond information about discovered food and the potential benefits signalers may gain from this calling behavior.

     

Demand curves for food in hens: Similarity under fixed-ratio and progressive-ratio schedules

Demand curves were generated for five domestic hens under progressive-ratio 5 schedules of food delivery and under fixed-ratio schedules of food delivery that began at fixed-ratio 5 and were incremented by 5 each session. All sessions ended after 10 consecutive minutes without a response. Although response rates at a given ratio were higher under the progressive-ratio schedule, all hens completed higher ratios under the fixed-ratio schedule. Similar, but not identical, demand curves were generated under progressive-ratio and fixed-ratio schedules. Under both schedules, consumption (reinforcers earned) decreased as cost (ratio size) increased. Data generally were well described by an equation in which elasticity of demand is constant, although an equation in which elasticity could vary accounted for slightly more of the variance.     

Small animal positron emission tomography in food sciences

Summary. Positron emission tomography (PET) is a 3-dimensional imaging technique that has undergone tremendous developments during the last decade. Non-invasive tracing of molecular pathways in vivo is the key capability of PET. It has become an important tool in the diagnosis of human diseases as well as in biomedical and pharmaceutical research. In contrast to other imaging modalities, radiotracer concentrations can be determined quantitatively. By application of appropriate tracer kinetic models, the rate constants of numerous different biological processes can be determined. Rapid progress in PET radiochemistry has significantly increased the number of biologically important molecules labelled with PET nuclides to target a broader range of physiologic, metabolic, and molecular pathways. Progress in PET physics and technology strongly contributed to better scanners and image processing. In this context, dedicated high resolution scanners for dynamic PET studies in small laboratory animals are now available. These developments represent the driving force for the expansion of PET methodology into new areas of life sciences including food sciences. Small animal PET has a high potential to depict physiologic processes like absorption, distribution, metabolism, elimination and interactions of biologically significant substances, including nutrients, ‘nutriceuticals’, functional food ingredients, and foodborne toxicants. Based on present data, potential applications of small animal PET in food sciences are discussed.     

Out-of-hours calls in a Leicestershire practice.

In one year, 920 "out-of-hours" calls were received by a partnership of three general practitioners working from a health centre in semi-rural Leicestershire. The partners on duty saw 588 patients. Out of 898 patients on whom information was available only 75 (8-5%) were referred to hospital, mainly as casualties. The results are compared with a study of deputising services, and it is concluded that a partnership covering its own out-of-hours calls can provide a more personal service and appears to make fewer demands on NHS resources.