Responses of domestic chicks to novel food as a function of sex, strain and previous experience

Individual Variation in Dietary Wariness Is Predicted by Head Color in a Specialist Feeder, the Gouldian Finch

Shifts in resource availability due to environmental change are increasingly confronting animals with unfamiliar food types. Species that can rapidly accept new food types may be better adapted to ecological change. Intuitively, dietary generalists are expected to accept new food types when resources change, while dietary specialists would be more averse to adopting novel food. However, most studies investigating changes in dietary breadth focus on generalist species and do not delve into potential individual predictors of dietary wariness and the social factors modulating these responses. We investigated dietary wariness in the Gouldian finch, a dietary specialist, that is expected to avoid novel food. This species occurs in two main head colors (red, black), which signal personality in other contexts. We measured their initial neophobic responses (approach attempts before first feed and latency to first feed) and willingness to incorporate novel food into their diet (frequency of feeding on novel food after first feed). Birds were tested in same-sex pairs in same and different head color pairings balanced across experiments 1 and 2. Familiar and novel food (familiar food dyed) were presented simultaneously across 5 days for 3 h, each. Gouldian finches fed on the familiar food first demonstrating food neophobia, and these latencies were repeatable. Birds made more approach attempts before feeding on novel than familiar food, particularly red-headed birds in experiment 1 and when partnered with a black-headed bird. Individuals consistently differed in their rate of incorporation of novel food, with clear differences between head colors; red-headed birds increased their feeding visits to novel food across experimentation equaling their familiar food intake by day five, while black-headed birds continually favored familiar food. Results suggest consistent among individual differences in response to novel food with red-headed birds being adventurous consumers and black-headed birds dietary conservatives. The differences in food acceptance aligned with responses to novel environments on the individual level (found in an earlier study) providing individuals with an adaptive combination of novelty responses across contexts in line with potential differences in movement patterns. Taken together, these novelty responses could aid in population persistence when faced with environmental changes.

Lack of neophobic responses to color in a jumping spider that uses color cues when foraging (Habronattus pyrrithrix)

Chemically defended prey often advertise their toxins with bright and conspicuous colors. To understand why such colors are effective at reducing predation, we need to understand the psychology of key predators. In bird predators, there is evidence that individuals avoid novelty-including prey of novel colors (with which they have had no prior experience). Moreover, the effect of novelty is sometimes strongest for colors that are typically associated with aposematic prey (e.g., red, orange, yellow). Given these findings in the bird literature, color neophobia has been argued to be a driving force in the evolution of aposematism. However, no studies have yet asked whether invertebrate predators respond similarly to novel colors. Here, we tested whether naive lab-raised jumping spiders (Habronattus pyrrithrix) exhibit similar patterns of color neophobia to birds. Using color-manipulated living prey, we first color-exposed spiders to prey of two out of three colors (blue, green, or red), with the third color remaining novel. After this color exposure phase, we gave the spiders tests where they could choose between all three colors (two familiar, one novel). We found that H. pyrrithrix attacked novel and familiar-colored prey at equal rates with no evidence that the degree of neophobia varied by color. Moreover, we found no evidence that either prey novelty nor color (nor their interaction) had an effect on how quickly prey was attacked. We discuss these findings in the context of what is known about color neophobia in other animals and how this contributes to our understanding of aposematic signals.

Variation in predator response to short-wavelength warning coloration

Warning coloration deters predators from attacking unpalatable prey, and is often characterized by long-wavelength colors, such as orange and red. However, warning colors in nature are more diverse and include short-wavelength colors, like blue. Blue has evolved as a primary defense in some animals but is not common. One hypothesis for the maintenance of this diversity is interspecific variation in predator responses to signals. We tested this hypothesis with galliform birds: Gambel's quail (Callipepla gambelii) and two domestic chicken breeds (Gallus gallus domesticus; Plymouth Rocks, Cochin Bantams). We measured innate avoidance and learning responses to only blue prey, only orange prey, and orange-and-blue prey, where the blue was iridescent to represent the natural coloration of the pipevine swallowtail butterfly (Battus philenor). We predicted birds would have similar responses to orange, but vary in response to blue. Upon first encounter, Cochin Bantams did not attack blue and Gambel's quail readily attacked, indicating innate avoidance by Cochin Bantams. Plymouth Rocks had no innate aversion to any color, lower attack latencies and attacked most prey items. Cochin Bantams and Gambel's quail both learned orange and orange-and-blue quicker than blue. Our results support the hypothesis that interspecific variation in predator response could maintain warning color diversity.

Short- and long-term dynamics of the physiological and behavioral response to heat stress and thymol supplementation in Japanese quail

Organisms have evolved endogenous timing systems that enable them to predict temporal changes and to coordinate complex internal processes. However, temporal dynamics of biological responses are most often ignored in fields such as dietary supplementation of farm animals exposed to artificial environmental challenges. Herein, we hypothesized that the potential for thymol (2-isopropyl-5-methylphenol) to alleviate physiological and behavioral consequences of heat stress is time-dependent on both long-term (i.e. weeks) and short-term (i.e. within day) time scales. First, during 3-weeks adult female Japanese quail (Coturnix japonica) were exposed daily to 9h of increased environmental temperature (34.2 ± 0.1 °C). Controls remained at standard temperatures (23.6 ± 0.1 °C). Simultaneously, half received thymol dietary supplementation and the other half a control basal diet. On day 4, both thymol and heat stress decreased body weight and feed intake respect to controls (basal, standard temperature). After three weeks, feed intake recovered for thymol groups. Therefore, we performed a second experiment focused on the critical first week of treatment, sampling variables three times a day. The beneficial effects of thymol supplementation were mainly observed during the morning, including prevention of high respiratory rates and reduction in the weight of droppings induced by heat stress, and increased walking under both temperatures. In summary, thymol's potential for alleviating heat stress consequences is time-dependent, and can be conceived as an emergent property resulting from the complex interplay between the dynamics of the biological response to thymol and heat stress. Findings highlight the importance of considering time-related factors when developing supplementation protocols to mitigate environmental challenges.

Statistical learning in domestic chicks is modulated by strain and sex

Statistical learning is a key mechanism for detecting regularities from a variety of sensory inputs. Precocial newborn domestic chicks provide an excellent model for (1) exploring unsupervised forms of statistical learning in a comparative perspective, and (2) elucidating the ecological function of statistical learning using imprinting procedures. Here we investigated the role of the sex of the chicks in modulating the direction of preference (for familiarity or novelty) in a visual statistical learning task already employed with chicks and human infants. Using both automated tracking and direct human coding, we confirmed chicks' capacity to recognize the presence of a statistically defined structure underlying a continuous stream of shapes. Using a different chicken strain than previous studies, we were also able to highlight sex differences in chicks' propensity to approach the familiar or novel sequence. This could also explain a previous failure to reveal statistical learning in chicks which sex was however not determined. Our study confirms chicks' ability to track visual statistics. The pivotal role of sex in determining familiarity or novelty preferences in this species and the interaction with the animals' strain highlight the importance to contextualize comparative research within the ecology of each species.

Reactions to novel objects in monkeys: what does it mean to be neophobic?

Animals' reactions to novel objects vary not only with zoological taxa and their ecology but also in the types of presented stimuli, the context, and individual characteristics. Behavioral reactions can vary from extremely neophobic (avoiding novel objects) to extremely neophilic (intense exploration of novel objects); most often, a mixture of these behavioral patterns appears. In primates, reactions toward novel objects vary according to species, age, sex, population, and the types of objects. Most experiments in this field have used a free exploration design with food or non-food objects. Here, we tested the reactions of captive male rhesus macaques using various stimuli, motivation levels, rewards, and time limits. We found that the monkeys explored and manipulated novel objects in various contexts, with little evidence of a neophobic response; however, environment, types of stimuli, and other parameters of the test can significantly affect monkeys' reactions.

Maternal care affects chicks' development differently according to sex in quail

Maternal behavior is known to influence the behavioral development of young. Recently, it was demonstrated that maternal behavior also differed according to sex of chicks and brood sex composition. So, here, we explored if these factors influenced behavioral development of quail chicks when they were brooded, and what characteristics of chicks and foster females could best explain this development. We studied three sets of chick pairs brooded by foster females: unisex male, unisex female, and mixed broods. We found that both emotivity profile and sociality depended on the sex: females were more reactive and less social than males. Females' emotivity profile was correlated with brood composition and foster female activity during maternal care. In males, only sociality was correlated with foster females' scores of aggressive rejection. Our results evidence that male and female chicks respond differentially to maternal behavior. This is discussed in terms of ecological and physiological constraints on development according to sex.

Artificially Increased Yolk Hormone Levels and Neophobia in Domestic Chicks

In birds there is compelling evidence that the development and expression of behavior is affected by maternal factors, particularly via variation in yolk hormone concentrations of maternal origin. In the present study we tested whether variation in yolk hormone levels lead to variation in the expression of neophobia in young domestic chicks. Understanding how the prenatal environment could predispose chicks to express fear-related behaviors is essential in order to propose preventive actions and improve animal welfare. We simulated the consequences of a maternal stress by experimentally enhancing yolk progesterone, testosterone and estradiol concentrations in hen eggs prior to incubation. The chicks from these hormone-treated eggs (H) and from sham embryos (C) that received the vehicle-only were exposed to novel food, novel object and novel environment tests. H chicks approached a novel object significantly faster and were significantly more active in a novel environment than controls, suggesting less fearfulness. Conversely, no effect of the treatment was found in food neophobia tests. Our study highlights a developmental influence of yolk hormones on a specific aspect of neophobia. The results suggest that increased yolk hormone levels modulate specifically the probability of exploring novel environments or novel objects in the environment.

Reconhecimento de cores de objetos e de alimentos de cromaticidades opostas por pintos de corte

Objetivou-se com esta pesquisa avaliar, por meio de testes de preferência, a capacidade de percepção de pintos de corte no reconhecimento de objetos e alimentos de diferentes cores. A pesquisa foi realizada no Brasil e consistiu no condicionamento de 60 pintos de um dia sexados, sendo 30 pintos machos e 30 pintos fêmeas, durante três dias, com esferas azuis e alimento vermelho, cores escolhidas por terem cromaticidades opostas. Após a fase de condicionamento, foi realizado um teste de preferência, no qual os animais eram colocados individualmente no centro de uma arena de teste com quatro opções, sendo elas: alimento vermelho; alimento azul; esferas vermelhas; esferas azuis. Cada ave foi avaliada durante 10 minutos. Foram registrados: o período de latência para a primeira bicada; o número de bicadas; a quantidade de bicadas sequenciais em cada tipo de objeto ou alimento; o tempo total da ave em cada compartimento ocupado e o primeiro compartimento ocupado. De acordo com os resultados, pintos fêmeas são menos inibidas quando em contato com uma nova situação em relação aos machos. Entretanto, os machos foram capazes de estabelecer um padrão de ambiente na fase de condicionamento e optaram pelo compartimento que estava mais próximo daquela situação associando, da maneira correta, a cor azul à esfera e a cor vermelha ao alimento. No geral, entre os tipos de cores de objetos e entre os tipos de cores de alimentos, as aves demoraram menos tempo para a decisão da escolha do alimento e da esfera azul, evidenciando-se maior atração, em um primeiro momento, por objetos ou alimentos dessa cor. Entre as duas cores de esferas, menor período de latência, maior número de interações, bem como maior tempo de permanência no local estiveram relacionados à esfera azul, verificando-se total preferência por esse objeto. Ao avaliar os tipos de cores de alimentos, foi possível observar que as maiores médias relacionadas ao número de bicadas e de bicadas sequenciais ocorreram com o alimento vermelho. Conclui-se, portanto, que as aves reconheceram o alimento vermelho e o objeto azul, sendo a cor azul a de maior atratividade para pintos de corte em relação à vermelha.

Moderate heat challenge increased yolk steroid hormones and shaped offspring growth and behavior in chickens

Background

Environmental challenges might affect the maternal organism and indirectly affect the later ontogeny of the progeny. We investigated the cross-generation impact of a moderate heat challenge in chickens. We hypothesized that a warm temperature–within the thermotolerance range- would affect the hormonal environment provided to embryos by mothers, and in turn, affect the morphology and behavioral phenotype of offspring.

Methodology/Principal Findings

Laying hens were raised under a standard thermal condition at 21°C (controls) or 30°C (experimental) for 5 consecutive weeks. A significant increase was observed in the internal temperature of hens exposed to the warm treatment; however plasma corticosterone levels remained unaffected. The laying rate was not affected, but experimental hens laid lighter eggs than the controls during the treatment. As expected, the maternal thermal environment affected yolk hormone contents. Eggs laid by the experimental hens showed significantly higher concentrations of yolk progesterone, testosterone, and estradiol. All chicks were raised under standard thermal conditions. The quality of hatchlings, growth, feeding behavior and emotional reactivity of chicks were analyzed. Offspring of experimental hens (C30 chicks) were lighter but obtained better morphological quality scores at hatching than the controls (C21 chicks). C30 chicks expressed lesser distress calls when exposed to a novel food. Unlike C21 chicks, C30 chicks expressed no preference for energetic food.

Conclusion/Significance

Our findings suggest that moderate heat challenge triggers maternal effects and modulate the developmental trajectory of offspring in a way that may be adaptive. This suggests that the impact of heat challenges on captive or wild populations might have a cross-generation effect.

Target-specificity of feral pig baits under different conditions in a tropical rainforest

Context The mitigation of feral pig (Sus scrofa) impacts in north Queensland’s World Heritage tropical rainforests is constrained by the lack of an effective and target-specific poison baiting method. Aims This study aimed to determine whether easily implemented bait presentation methods or seasonal variation in bait acceptability could be used to selectively reduce the consumption of feral pig baits by non-target species. Methods We exposed manufactured feral pig baits to pigs and non-target species in the field, and compared bait encounter, sampling and consumption rates for different functional groups of species among three different types of bait presentation and composition. We then exposed baits under different seasonal conditions and related bait encounter and consumption by different functional groups to seasonally variable phenomena. Key results Shallow burial greatly reduced bait consumption by most non-target species, but not dingoes (Canis lupus dingo). Nocturnal bait distribution and seasonal baiting were less useful. Pigs showed substantial seasonal variation in physiological condition, suggesting that pigs should be more susceptible to consuming novel foods, such as baits, after periods of low rainfall. However, few pigs consumed the manufactured baits used in this study. Conclusions Manufactured baits are not currently suitable for widespread use in the region. However, shallow burial should provide an effective method of reducing non-target bait-take if baits can be made more attractive and acceptable to pigs and less acceptable to dingoes. Implications Future efforts to enable effective feral pig control in the region should focus on developing baiting materials that are more attractive to pigs and unappealing to dingoes.

Neonatal acute stress by novelty in the absence of social isolation decreases fearfulness in young chicks

Two hours after hatching (Day 0), groups of chicks from both sexes were housed either individually (IND) or socially in pairs (SOC) for 24 h. On Day 1, for each of the two conditions, half of the chicks were individually exposed to early novelty for 10 min, which comprised being placed in a novel-cage with small pebbles glued to the floor. The other half (controls) remained in the home-cage (IND-C and SOC-C). Thus, the IND-N group was exposed to early novelty, and the SOC-N+I group was exposed to early novelty and social isolation. Subsequently, all groups were mixed and socially reared until reaching 15 days of age. At this time, chicks were exposed to open field (OF) and tonic immobility (TI) tests. The IND-N group showed a shorter latency to ambulate in the OF test, shorter immobility duration in the TI test, a reduced plasma corticosterone concentration and increased flunitrazepam sensitive-GABA(A) receptor basal forebrain density compared with other groups, indicating that a neonatal novelty induced lower fearfulness in young chicks. In contrast, the effect of neonatal novelty was abolished by a simultaneous effect of social isolation in the SOC-N+I group. Thus, early post-hatch life events such as early novelty could improve a bird's later ability to cope with new stressful events. In addition, it is possible that both novelty and social isolation act on different neurobiological processes.

The effect of diet change on the behaviour of layer pullets

Frequent diet change has been identified as a risk factor for feather pecking in commercial flocks but the mechanism underlying this association is not known. In this experiment we simulated a commercial change of diet between high quality (HQ) 19% protein, and low quality (LQ) 15% protein, diets. Twelve pairs of birds were fed both diets simultaneously for 38 days to determine whether clear preferences for the diets existed. A further 12 triplets of birds were fed either HQ or LQ diets for 38 days to examine any absolute effects of quality on behaviour. The remaining triplets received, on day 29, either a LQ to HQ diet change (n = 12 groups) or an HQ to LQ diet change (n = 12 groups). Half of the groups in these diet change treatments received oregano oil as a potential ‘masking’ agent to disguise the diet change. No dietary preferences were detected and there were no absolute effects of diet on behaviour. Diet change provoked significant increases in beak-related activity. Specifically, affiliative pecking (allopreening directed towards comb or beak) was increased after diet change. Masking the diet reduced the effects of diet change. Injurious pecking remained at low levels throughout the experiment and was not affected by diet change, but the relationship between affiliative pecking and subsequent injurious pecking requires further investigation.

Response toward novel stimuli in a group of tufted capuchins (Cebus libidinosus) in Brasília National Park, Brazil

We investigated responses toward novel foods and novel objects by wild capuchins that routinely exploit visitors' foods in Brasília National Park. Given the capuchins' daily exposure to human foods and objects, we expected them to be more explorative toward novel foods and objects compared to capuchins that are not habituated to visitors. However, since the safety and palatability of potential foods have to be learned, we also expected the capuchins to be cautious about eating novel foods, as has been reported for wild and captive capuchins. Stimuli were presented on a platform in four experimental conditions: familiar food (FF), novel food (NF), familiar food plus novel object (FF+O), and novel food plus novel object (NF+O). Latencies to approach and contact the platform, and to approach and to ingest food did not differ across conditions. Nevertheless, the capuchins were significantly more responsive (measured in terms of interest, manipulation, etc.) toward familiar foods than novel foods, and ate significantly more of the former. In other words, their explorative response toward novel foods led to little consumption. Our results do not support the "readiness to eat" hypothesis, according to which a lower readiness to eat and food neophobia are the consequences of the presence of a distracting novel object. The finding that capuchins explore novel stimuli but remain cautious about eating novel foods supports the view that neophilia and neophobia are motivationally independent responses.

Effect of Diet Change on the Behavior of Chicks of an Egg-Laying Strain

Injurious pecking has serious welfare consequences in flocks of hens kept for egg laying, especially when loose-housed. Frequent diet change is a significant risk for injurious pecking; how the mechanics of diet change influence pecking behavior is unknown. This study investigated the effect of diet change on the behavior of chicks from a laying strain. The study included a 3-week familiarity phase: 18 chick pairs received unflavored feed (Experiment 1); 18 pairs received orange oil-flavored (Experiment 2). All chicks participated in a dietary preference test (P); a diet change (DC); or a control group (C), 6 scenarios. All P chicks preferred unflavored feed. In Experiment 1, DC involved change from unflavored to orange-flavored; Experiment 2, orange- flavored to unflavored. Compared with controls, Experiment 2 DC chicks exhibited few behavioral differences; Experiment 1 DC chicks exhibited increased behavioral event rates on Days 1 and 7. They pecked significantly longer at their environment; by Day 7, they showed significantly more beak activity. There was little evidence of dietary neophobia. Change from more preferred to less preferred feed led to increased activity and redirected pecking behavior.

Do broiler chicks have a cognitive representation of food quality? Appetitive, behavioural and ingestive responses to a change in diet quality

It has been observed that when a new diet formulation, or a new batch of the same diet formulation, is presented to poultry, there is a transitory suppression of feeding. It appears that the birds do not recognise the food as being edible, or classify it as being 'unknown'. In order to understand more about food recognition and rejection, the aim of this experiment was to determine whether cognitive processes are involved. Sixteen groups of four broiler chicks were used, and were fed a low quality diet in their home pens. The groups of chicks were trained to run a winding maze to gain access to a high quality diet in a test trough for 15min per day. When training was completed, the feed in the test trough for eight of the groups was changed to that which they received in the home pen, while the other eight groups received no change as a control. Time to traverse the runway did not show an immediate decrease on the day after the change (P>0.05) as would be expected if the birds used a cognitive comparison to determine speed of approach to the test trough. However, the experimental groups were significantly slower compared to the control groups after 4 days (P<0.05). The behaviour observed on the day of the change was indicative of frustration with more scratching and hurried movements shown (P<0.05), and less pecking at feed (P<0.01). Food consumption was lower for experimental groups compared to control groups on all days from the day of change onward (P<0.001). It was concluded that although there was no definitive evidence for the presence of a cognitive representation of food, this may have been due in part to the testing of groups of birds rather than individuals, and the way in which food quality is perceived. The occurrence of behaviours indicative of frustration suggest that a cognitive expectation may have been present.

Predator experience on cryptic prey affects the survival of conspicuous aposematic prey

Initially, aposematism, which is an unprofitable trait, e.g. noxiousness conspicuously advertised to predators, appears to be a paradox since conspicuousness should increase predation by naive predators. However, reluctance of predators for eating novel prey (e.g. neophobia) might balance the initial predation caused by inexperienced predators. We tested the novelty effects on initial predation and avoidance learning in two separate conspicuousness levels of aposematic prey by using a 'novel world' method. Half of the wild great tits (Parus major) were trained to eat cryptic prey prior to the introduction of an aposematic prey, which potentially creates a bias against the aposematic morph. Both prey types were equally novel for control birds and they should not have shown any biased reluctance for eating an aposematic prey. Knowledge of cryptic prey reduced the expected initial mortality of the conspicuous morph to a random level whereas control birds initially ate the conspicuous morph according to the visibility risk. Birds learned to avoid conspicuous prey in both treatments but knowledge of cryptic prey did not increase the rate of avoidance learning. Predators' knowledge of cryptic prey did not reduce the predation of the less conspicuous aposematic prey and additionally predators did not learn to avoid the less conspicuous prey. These results indicate that predator psychology, which was shown as reluctance for attacking novel conspicuous prey, might have been important in the evolution of aposematism.

Pecking preferences and pre-dispositions in domestic chicks: implications for the development of environmental enrichment devices

Environmental enrichment is thought likely to benefit chickens and farmers in many ways; these include reduced fearfulness and feather pecking and improved productivity. Enrichment devices would intuitively be more effective if they reliably attracted and sustained appreciable interest but many fail to do so. This may reflect the fact that the choice of stimuli often reflects availability and human preconceptions rather than a critical consideration of the birds' preferences and pre-dispositions. We had previously identified string as a particularly attractive pecking stimulus for chicks and adult hens (Gallus gallus domesticus) of a laying strain (ISA Brown). In the present study we found that chicks of another laying strain (Lohmann Brown) also pecked sooner and more at a bunch of string than at chains or beads (Experiment 1). White or yellow strings were preferred to red, green or blue ones (Experiment 2) and white string elicited more pecking than did combinations of white and yellow or of all five colours (Experiment 3). Varying the length and width of the bunches of string exerted no detectable effects on pecking (Experiment 4) whereas incorporating small, shiny beads in the white string devices actually reduced pecking (Experiment 5). Virtually all the devices elicited progressively more interest with repeated presentation; this trend was particularly marked for white string. Collectively, the present findings demonstrate that young domestic chicks have clear and specific pecking preferences. Although the magnitude of response varied across experiments, white string consistently elicited the most interest. Our two main conclusions are: (i) white or yellow strings were particularly attractive stimuli that drew increasing interest, at least in the short term, and (ii) simple devices were preferred to more complex ones, or at least to those used here.

Early locomotor behaviour in genetic stocks of chickens with different growth rates

Reduction in exercise increases the occurrence of lameness in meat-type chickens. Locomotor activity is dramatically reduced during the finishing period in chickens from fast-growing genetic types compared to slow-growing genetic types, but it is not known whether this difference is already present during the starting period and may be influenced by genetic factors. In order to define the effect of genetic origin on early locomotor behaviour, exercise was compared from 1 to 22 days of age in two meat-type chicken stocks differing in growth rate: male broilers (B) which grow fast and are often lame, and male "label rouge" chickens (L) which grow slowly and are rarely lame.Time budget (lying, standing, drinking, eating, walking) was measured by scanning in six repetitions of five birds (density=2.5 birds/m(2)) at 1, 8, 15 and 17 days of age. Standing bouts were analysed by focal sampling at 2-3, 6-7, 13-14 and 20-21 days of age.B chicks spent less time standing than L chicks at 15 days of age (B=13+/-2%, L=24+/-1%, P<0.01) and 17 days of age, and spent more time lying at 17 days of age (B=73+/-3%, L=60+/-4%, P<0.05).The major part (74%) of the total active time observed by focal sampling was linked to feeding activity. At 2 and 3 days, the activity of B chicks was half that of L chicks during standing bouts (duration of walking per bout: 19+/-4 s for B; 45+/-4 s for L, P<0.05). The activity observed by focal sampling during non-feeding bouts at 20-21 days was significantly correlated with the corresponding data recorded at 2-3 days in the same chicks in the B stock but not in the L stock.We concluded that (1) both B and L genetic stocks have the same overall activity during the first 3 days of age (scanning) but they exhibit different organisation and composition of standing bouts (focal sampling). (2) Genetic factors are probably involved in the expression of locomotor behaviour in very young chicks. (3) The correlations between the levels of activity at early and later ages suggest that selection of young mobile broiler chicks might increase activity at a later age and might therefore reduce the occurrence of leg abnormalities.

Cholecystokinin A receptor antagonist inhibits feed memory in Japanese quail

Cholecystokinin (CCK) modulates learning and memory processes in mammals. The main objective of this work was to study the effect of two cholecystokinin receptor antagonists (CCKA antagonist devazepide and CCKB antagonist PD135158) on feed memory processes in Japanese quail. Memorization of colored food was measured by comparing the feeding behavior of 6- to 8-day-old quails during two successive sessions of 10 min after a 30-min fast in the test box, intersession interval: 24 h. The CCKA antagonist devazepide (0.1 mg/kg, b.wt) injected after the first session appears to disrupt feed memory formation. The CCKB antagonist PD135158 at the same dose induced a similar trend, but no significant effect on feed memorization could be measured. It is suggested that CCKA antagonist inhibits feed memory processes.