The individual nest box as a super-stimulus for domestic hens

Following reports of inconsistent nest choice by hens in groups, choice of nest boxes by solitary hens was investigated. Thirty-two hens of a White Leghorn strain were each isolated with six nest boxes while they laid six eggs. From 16 hens, eggs were collected daily. Only one of these birds laid all her eggs in one nest box, and others used up to four boxes. The other 16 were allowed to accumulate eggs, and these were significantly more consistent in nest choice. Five used only one box. However, the other 11 of this group showed incomplete consistency.An explanation for inconsistent nest choice was suggested by a second experiment. The importance of enclosure in nest-site selection was tested in hens of White Leghorn and Rhode Island Red strains. Individuals about to lay their first egg were isolated with a choice of two types of nest box, selected from five types of different enclosure. Exposed nests, of similar dimensions to natural nests, were rarely used by either strain. By contrast, more enclosed nests were strongly selected. These results indicate that enclosure is an important stimulus in nest-site selection, and that artificial nest boxes, which are more enclosed than natural sites, act as super-normal stimuli (or “super-stimuli”). Choices between super-stimuli are likely to be equivocal, which accounts for inconsistency in the use of nest boxes and other features of the nesting behaviour of domestic hens.     

Thermoregulation in the domestic fowl exposed to a natural climate

Thermoregulatory responses in the resting and the fasting states were studied from July to February in 20 White Leghorn laying hens in a hot-dry climate (41°C mean maximal summer temperature) and in 20 hens transferred in June from the hot-dry climate to a warm climate (30°C mean maximal summer temperature). The relationships of metabolic rates, skin and rectal temperature to ambient temperatures were similar in both climatic groups.In both groups metabolic rates were 18% lower in summer than in winter. The thermal comfort temperature zone and rectal temperatures were significantly higher than those found in controlled climates. The relationship of metabolic rate to mean body temperature is suggested for defining the thermal comfort temperature zone.

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Zusammenfassung Die Thermoregulation von 20 weissen Leghorn Legehennen im Ruhe-und Nüchternzustand wurde in einem heiss-trocken Klima (41°C mittlere max. Sommertemperatur) untersucht und bei 20 Hennen, die im Juni aus einem heiss-trockenen in ein warmes Klima (30°C mittlere max. Sommertemperatur) überführt wurden. Die Beziehung zwischen Stoffwechselrate, Haut- und Rektaltemperaturen und Umgebungstemperaturen waren in beiden Klimagruppen gleich. In beiden Gruppen war die Stoffwechselrate im Sommer 18% niedriger als im Winter. Die Temperaturen der Komfortzone und die Rektaltemperaturen waren signifikant höher als in kontrollierten Klimaten. Es wird empfohlen, die Beziehungen zwischen Stoffwechselrate und mittlerer Körpertemperatur zur Definition der Komforttemperaturzone zu verwenden.

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Resume On a examiné les phénomènes de thermorégulation à l'état de repos et à jeûn de 20 poules pondeuses blanches Leghorn placées d'une part de juillet à février dans un climat très chaud et sec (41°C de max. moyen d'été) et d'autre part transférées en juin du climat très chaud et sec dans un climat chaud (30°C de max. moyen d'été). La relation entre le taux de métabolisme d'une part, la température de la peau et la température rectale d'autre part fut analogue dans les deux groupes. Dans les deux groupes, le taux de métabolisme fut de 18% inférieur en été à ce qu'il fut en hiver. La température de la zone de confort et la température rectale y furent plus levées, et cela de façon significative, que pour les bêtes maintenues en climat de contrôle. On propose d'utiliser la relation entre le taux de métabolisme et la température moyenne du corps pour définir la zone thermique de confort.

     

The effects of regular handling on fear responses in the domestic chick

Reduction of fear in the domestic chick by regular handling was assessed and an attempt was made to determine whether such an effect was due specifically to reduced fear of human beings or to a general reduction in fearfulness. Regular handling decreased the tonic immobility response, a fear-potentiated phenomenon, and increased approach to a human being, but had no effect on approach towards an inanimate object. These findings were common to three strains (two layer, one broiler), and suggest that handling does not depress general fearfulness, but specifically reduces fear of human beings, presumably through habituation.     

The effect of light on the choice of nests by domestic hens

The involvement of light in nest-site selection by domestic fowls was tested in two strains of laying hens at two stages of maturity. Individuals that were about to lay an egg were isolated in a pen and given a choice of two sorts of nest-box, one illuminated internally and the other without illumination. Nearly all birds tested laid in one of the boxes provided, but their choice of dark or light conditions varied strongly with both strain and maturity. Only one of the four categories of hen, those of a White Leghorn strain laying their first egg, exhibited the expected preference for dark nests. Birds of a strain derived from Rhode Island Reds were more likely to lay in light nests, and with both strains hens which had previously been laying in open pens showed greater preference for light nests than did naïve individuals. These results suggest that light intensity is not a fundamental factor influencing nest-site selection, but it may nevertheless haveto be considered in the management of laying hens.     

Neural processing of auditory looming in the human brain

Acoustic intensity change, along with interaural, spectral, and reverberation information, is an important cue for the perception of auditory motion. Approaching sound sources produce increases in intensity, and receding sound sources produce corresponding decreases. Human listeners typically overestimate increasing compared to equivalent decreasing sound intensity and underestimate the time to contact of approaching sound sources. These characteristics could provide a selective advantage by increasing the margin of safety for response to looming objects. Here, we used dynamic intensity and functional magnetic resonance imaging to examine the neural underpinnings of the perceptual priority for rising intensity. We found that, consistent with activation by horizontal and vertical auditory apparent motion paradigms, rising and falling intensity activated the right temporal plane more than constant intensity. Rising compared to falling intensity activated a distributed neural network subserving space recognition, auditory motion perception, and attention and comprising the superior temporal sulci and the middle temporal gyri, the right temporoparietal junction, the right motor and premotor cortices, the left cerebellar cortex, and a circumscribed region in the midbrain. This anisotropic processing of acoustic intensity change may reflect the salience of rising intensity produced by looming sources in natural environments.     

Changes in the frequency of the hippocampal theta-rhythm in the dog exposed to a conditioned food stimulus

Frequency changes of hippocampal theta-rhythm in the process of elaboration of coinciding or delayed instrumental alimentary reflex was studied in two dogs. Determination of dominating frequency of rhythmical activity was carried out by means of mathematical methods of analysis on a computer. It was found out, that during the action of conditioned alimentary stimulus the frequency of dominating oscillations became enhanced. Animals with a more frequent initial theta-rhythm formed the delayed alimentary reflex more rapidly.     

Social preferences of domestic hens for domestic vs. red junglefowl males and females

The striking dimorphism of male and female junglefowl may have evolved in large part due to female choice of mates. However, domestic fowl hens consistently chose domestic, not junglefowl, males as well as females in preference tests. Either genetic predisposition to favor junglefowl morphological features over those of the domestic types utilized in these tests was overridden by experience or such genetic predisposition does not exist in the breed we tested.     

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.     

Habituation of unconditioned fear can be attenuated by the presence of a safe stimulus: assessment using the neophobic response of the rat

Protection from extinction of conditioned fear has been demonstrated when a conditioned inhibitor of fear is presented during extinction treatment. The present study assessed if similar results could be obtained during the analogous habituation of unconditioned fear. The neophobic response typically elicited by the presentation of a novel flavor was used as a model of unconditioned fear. Consumption by rats was used to ascertain the impact of nonreinforced exposure to a novel flavor either alone, in compound with another novel flavor, or in compound with a safe flavor (i.e., a flavor previously trained as a conditioned inhibitor for illness). The presentation of the novel flavor alone in the absence of illness reduced neophobia. However, exposure to the novel flavor in compound with the safe flavor reduced habituation of neophobia. This effect was not observed when the novel flavor was exposed in compound with another novel flavor. These results suggest that removing safe stimuli from the therapeutical environment might improve the effectiveness of exposure therapy in the treatment of unconditioned fear.     

Ultradian and circadian CO2 emission variations in nocturnal and diurnal animals exposed to a light stimulus

1. Carbon dioxide emission (VCO2) has been continuously recorded in three laboratory animal species (Sprague-Dawley rats, Japanese quail, Hartley guinea-pigs) which differ by their nocturnal and diurnal activities. A 100 lux stimulus has been delivered at various time intervals. 2. A regular alternation of 12, 3 or 1.5 hr light (L) and darkness (D) gives VCO2 circadian and ultradian rhythms of 24, 6 or 3 hr periods, respectively, in quail and rats. 3. Such circadian and ultradian LD rhythms are not induced in all guinea-pigs. 4. The amplitudes of the VCO2 responses are greatest at D----L when the animals have a maximum diurnal activity and at L----D when their maximum activity is nocturnal. 5. Interactions between circadian and ultradian rhythms are seen in all LD experiments, as well as in continuous light (LL) or continuous dark (DD). 6. No more well-marked or even inverted VCO2 responses to the light stimuli may occur after several days of exposure to these LD alternations.     

Hippocampal place cells acquire location-specific responses to the conditioned stimulus during auditory fear conditioning

We recorded neurons from the hippocampus of freely behaving rats during an auditory fear conditioning task. Rats received either paired or unpaired presentations of an auditory conditioned stimulus (CS) and an electric shock unconditioned stimulus (US). Hippocampal neurons (place and theta cells) acquired responses to the auditory CS in the paired but not in the unpaired group. After CS-US pairing, rhythmic firing of theta cells became synchronized to the onset of the CS. Conditioned responses of place cells were gated by their location-specific firing, so that after CS-US pairing, place cells responded to the CS only when the rat was within the cell's place field. These findings may help to elucidate how the hippocampus contributes to context-specific memory formation during associative learning.