Mothers’ fear of human affects the emotional reactivity of young in domestic Japanese quail

Traditional sexing methods and external egg characteristics combination allow highly accurate early sex determination in an endangered native turkey breed

Early sex determination methods are not only crucial in the worldwide massive poultry industry, but also for small-holder producers. The profitability of sexing techniques must be accounted for when aiming to boost management, nutrition, and conservation practices in endangered poultry breeds. This becomes pivotal when the local breed dealt with belongs to an understudied species, such as the turkey. So, the main objective of this study is to identify which method combination may report a higher likelihood of successful sex determination in poults across the three-pattern varieties of the Andalusian turkey breed. A total of 84 one to two days old Andalusian turkey poults (42 black, 28 black-roan, and 14 bronze-roan) were evaluated in this study. Sex determination was performed using 15 methods, which included testing external egg metrics and eggshell color, poult morphological appraisal and phaneroptics, and behavioral traits. Possible differences across plumage varieties and the interaction between sex and plumage were observed when external egg quality was measured. Sex determination through behavioral methods in black base feathered (black and black-roan) male sex individuals showed seven times higher sensitivity when compared to the rest of the studied individuals (χ2 = 7.14, df = 1, P < 0.01). In contrast, for the black-roan plumage females, the method based on the color of down feathers was approximately four times more sensitive (χ2 = 3.95, df = 1, P ≤ 0.05). For the bronze-roan pattern, none of the sexing techniques was reported to efficiently predict sex itself. However, the most proper method combination to determine sex, independent of plumage color, was physical external egg characteristics, the color of down feathers, and behavioral approaches (“English method” and “slap technique”). The specificity values were found to be 49.12, 93.33, and 100%, while the sensitivity values were observed to be 74.64, 91.03, and 100%, which translated into accuracy of 63.10, 92.26, and 100% in black, black-roan, and bronze-roan poults, respectively. Our results suggest that the method combination tested in this study could be considered a highly accurate, simple, and affordable alternative for sex determination in turkeys. This could mean a pivotal advance for small producers of turkeys, as early sex detection can help to plan timely conservational management strategies, which is of prominent importance in the context of endangered poultry breeds.

Fos expression in the medial preoptic area and nucleus accumbens of female Japanese quail (Coturnix japonica) after maternal induction and interaction with chicks

The neural system underlying maternal caregiving has often been studied using laboratory rodents and a few other mammalian species. This research shows that the medial preoptic area (mPOA) integrates sensory cues from the young that, along with hormonal and other environmental signals, control maternal acceptance of neonates. The mPOA then activates the mesolimbic system to drive maternal motivation and caregiving activities. How components of this neural system respond to maternal experience and exposure to young in non-mammals has rarely been examined. To gain more insight into this question, virgin female Japanese quail (Coturnix japonica) were induced to be maternal through four days of continuous exposure to chicks (Maternal), or were not exposed to chicks (Non-Maternal). Chicks were removed overnight from the Maternal group and half the females from each group were then exposed to chicks for 90 minutes (Exposed), or not exposed to chicks (Non-Exposed), before euthanasia. The number of Fos-immunoreactive (Fos-ir) cells was examined as a marker of neuronal activation. As expected, repeated exposure to chicks induced caregiving behavior in the Maternal females, which persisted after the overnight separation, suggesting the formation of a maternal memory. In contrast, Non-Maternal females were aggressive and rejected the chicks when exposed to them. Exposed females, whether or not they were given prior experience with chicks (i.e., regardless if they accepted or rejected chicks during the exposure before euthanasia), had more Fos-ir cells in the mPOA compared to Non-Exposed females. In the nucleus accumbens (NAC), the number of Fos-ir cells was high in all Maternal females whether or not they were Exposed to chicks again before euthanasia. In the lateral bed nucleus of the stria terminalis, a site involved in general stress responding, groups did not differ in the number of Fos-ir cells. These data indicate a conserved role for the mPOA and NAC in maternal caregiving across vertebrates, with the mPOA acutely responding to the salience rather than valence of offspring cues, and the NAC showing longer-term changes in activity after a positive maternal experience even without a recent exposure to young.

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.

Anti-predator behaviour of adult red-legged partridge (Alectoris rufa) tutors improves the defensive responses of farm-reared broods

The aim of this work was to improve natural anti-predator behaviour of farm-reared gamebirds. We evaluated the anti-predator behaviour of reared red-legged partridge Alectoris rufa chicks kept in brooder houses in large groups (>350 chicks), trained and not trained by parent red-legged partridges acting as experienced tutors. The experiment consisted of two conditioned tests (a raptor model and a human) and two control tests, which were conducted during three consecutive phases of life (1-4, 15-17 and 30-32 d after hatching). The motor anti-predator behaviour, its duration, the intensity of response in chicks and alarm calls elicited by adults were recorded. Tutors elicited aerial alarm calls (76% of tests) and showed prolonged crouching (59% of tests) in response to the raptor model whereas uttering the ground alarm call (73% of tests) and showing vigilance behaviour (78% of tests) was the main pattern during the human test. Trained and not trained chicks showed similar motor behaviour in response to the raptor model (crouching) and the human test (escaping), but frequency of strong responses (all chicks responding) from chicks trained with tutors was double that of chicks trained without them, and chicks trained with tutors showed a higher frequency of long responses (41-60 s). This study indicates that anti-predator training programmes before release may improve behaviour of farm-reared partridges which may confer benefits to survival of birds.

Effects of Dark Brooders on Behavior and Fearfulness in Layers

Chicks require heat to maintain body temperature during the first weeks after hatch. This may be provided by dark brooders; i.e. , horizontal heating elements equipped with curtains. The objective was to test effects of rearing layer chicks with dark brooders on time budget and fearfulness. Behavioral observations were performed during the first six weeks of age. Three different fear tests were conducted when the birds were age 3-6, 14-15 and 26-28 weeks. During the first four days, brooder chicks rested more than control chicks whereas they spent less time drinking, feather pecking and on locomotion ( p ≤ 0.009). On days 16, 23, 30 and 42, brooder chicks spent less time on feather pecking, locomotion and fleeing ( p ≤ 0.01) whereas foraging and dust bathing occurred more often on day 42 ( p ≤ 0.032). Brooder birds had shorter durations of tonic immobility at all ages ( p = 0.0032), moved closer to the novel object at age 15 weeks ( p < 0.0001), and had shorter latencies to initiate locomotion in the open-field test at age 28 weeks ( p < 0.0001). Results support the suggestion that dark brooders can be a successful method of reducing or preventing fear and feather pecking in layers.

Influences of Maternal Care on Chicken Welfare

In domestic chickens, the provision of maternal care strongly influences the behavioural development of chicks. Mother hens play an important role in directing their chicks' behaviour and are able to buffer their chicks' response to stressors. Chicks imprint upon their mother, who is key in directing the chicks' behaviour and in allowing them to develop food preferences. Chicks reared by a mother hen are less fearful and show higher levels of behavioural synchronisation than chicks reared artificially. In a commercial setting, more fearful chicks with unsynchronised behaviour are more likely to develop behavioural problems, such as feather pecking. As well as being an inherent welfare problem, fear can also lead to panic responses, smothering, and fractured bones. Despite the beneficial effects of brooding, it is not commercially viable to allow natural brooding on farms and so chicks are hatched in large incubators and reared artificially, without a mother hen. In this review we cover the literature demonstrating the important features of maternal care in domestic chickens, the behavioural consequences of deprivation and the welfare implications on commercial farms. We finish by suggesting ways to use research in natural maternal care to improve commercial chick rearing practice.

Short- and long-term effects of unpredictable repeated negative stimuli on Japanese quail's fear of humans

Numerous aversive events occur in poultry production, and if repeated and unpredictable, can result in an impaired welfare. Some events such as handling can be perceived negatively and it is of interest to understand how humans' behaviour could affect poultry's behaviours and especially its avoidance of humans. Our aim was to evaluate short- and long-lasting effects of a 3-week procedure involving unpredictable repeated negative stimuli (URNS) applied during the post-juvenile period on quail's reactivity to humans. We compared the reactions of two sets of quail: URNS was applied to one set (treated quail) and the other set was left undisturbed (control quail). When two weeks old, treated quail were exposed to a variety of negative stimuli, either applied automatically or involving human presence. One and seven weeks after the termination of the procedure, the reactivity of control and treated quail to a passive human being was evaluated. Furthermore, the experimenter with her hand on a trough containing a mealworm assessed the propensity of quail of both groups to habituate to feed close to a human being. In the presence of a seated observer, treated quail were more inhibited and more alert than control quail. Likewise, seven weeks after the end of the URNS procedure, more treated than control quail adopted a fear posture. Moreover, whereas control quail spent as much time in the different areas of their cages, treated quail spent more time in the rear part of their cages. Finally, whereas control quail habituated gradually to feed near the experimenter's hand, treated quail did not. All these tests evidence negative short- and long-term effects on treated quail's reactivity to a passive human being and on their habituation to a human being when her presence is positively reinforced. This highlights the importance of young poultry's experience with humans in production.

Motherless quail mothers display impaired maternal behavior and produce more fearful and less socially motivated offspring

Early maternal deprivation impairs the behavioral development of young individuals. Recently, strong differences between mothered and maternally deprived chicks have been reported concerning their emotionality, sociality, and spatial skills. Here we investigated long-term and cross-generational impacts of maternal deprivation by comparing the characteristics of the non-reproductive and the maternal behavior of 22 mothered and 22 non-mothered adult female Japanese quail (Coturnix c. japonica) and by comparing the behavior of their respective fostered chicks. We reveal that non-brooded mothers were more fearful and less competent in spatial tasks and expressed impaired maternal care, characterized by more aggression towards chicks, higher activity rates, and more abnormal pacing during the first days of the care period. Chicks' behavior was clearly affected by maternal care inducing strong differences in their fearfulness and social motivation. Our results show both long-term and cross-generational impacts of early maternal deprivation in precocial birds.

Age affects the expression of maternal care and subsequent behavioural development of offspring in a precocial bird

Variations of breeding success with age have been studied largely in iteroparous species and particularly in birds: survival of offspring increases with parental age until senescence. Nevertheless, these results are from observations of free-living individuals and therefore, it remains impossible to determine whether these variations result from parental investment or efficiency or both, and whether these variations occur during the prenatal or the postnatal stage or during both. Our study aimed first, to determine whether age had an impact on the expression of maternal breeding care by comparing inexperienced female birds of two different ages, and second, to define how these potential differences impact chicks’ growth and behavioural development. We made 22 2-month-old and 22 8-month-old female Japanese quail foster 1-day-old chicks. We observed their maternal behaviour until the chicks were 11 days old and then tested these chicks after separation from their mothers. Several behavioural tests estimated their fearfulness and their sociality. We observed first that a longer induction was required for young females to express maternal behaviour. Subsequently as many young females as elder females expressed maternal behaviour, but young females warmed chicks less, expressed less covering postures and rejected their chicks more. Chicks brooded by elder females presented higher growth rates and more fearfulness and sociality. Our results reveal that maternal investment increased with age independently of maternal experience, suggesting modification of hormone levels implied in maternal behaviour. Isolated effects of maternal experience should now be assessed in females of the same age. In addition, our results show, for first time in birds, that variations in maternal care directly induce important differences in the behavioural development of chicks. Finally, our results confirm that Japanese quail remains a great laboratory model of avian maternal behaviour and that the way we sample maternal behaviour is highly productive.

Hand-rearing reduces fear of humans in European starlings, Sturnus vulgaris

Pending changes in European legislation ban the use of wild-caught animals in research. This change is partly justified on the assumption that captive-breeding (or hand-rearing) increases welfare of captive animals because these practices result in animals with reduced fear of humans. However, there are few actual data on the long-term behavioural effects of captive-breeding in non-domestic species, and these are urgently needed in order to understand the welfare and scientific consequences of adopting this practice. We compared the response of hand-reared and wild-caught starlings to the presence of a human in the laboratory. During human presence, all birds increased their general locomotor activity but the wild-caught birds moved away from the human and were less active than the hand-reared birds. After the human departed, the wild-caught birds were slower to decrease their activity back towards baseline levels, and showed a dramatic increase in time at the periphery of the cage compared with the hand-reared birds. We interpret these data as showing evidence of a greater fear response in wild-caught birds with initial withdrawal followed by a subsequent rebound of prolonged attempts to escape the cage. We found no effects of environmental enrichment. However, birds in cages on low shelves were less active than birds on upper shelves, and showed a greater increase in the time spent at the periphery of their cages after the human departed, perhaps indicating that the lower cages were more stressful. In demonstrating reduced fear of humans in hand-reared birds, our results support one of the proposed welfare benefits of this practice, but without further data on the possible welfare costs of hand-rearing, it is not yet possible to reach a general conclusion about its net welfare impact. However, our results confirm a clear scientific impact of both hand-rearing and cage position at the behavioural level.

Increased yolk testosterone facilitates prenatal perceptual learning in Northern bobwhite quail (Colinus virginianus)

Prenatal learning plays an important role in the ontogeny of behavior and birds provide a useful model to explore whether and how prenatal exposure to hormones of maternal origin can influence prenatal learning and the development of behavior. In this study we assessed if prenatal exposure to yolk testosterone can influence auditory learning in embryos of Northern bobwhite quail (Colinus virginianus). We experimentally enhanced testosterone concentrations in bobwhite quail eggs prior to incubation. The embryos from these T-treated eggs as well as control embryos that had received the vehicle-only or were non-treated were exposed to an individual bobwhite hen's maternal call for 120 min over the course of the day prior to hatching. All chicks were tested at 24 h following hatching for their auditory preference between the familiar bobwhite maternal call versus an unfamiliar bobwhite maternal call. T-treated chicks spent significantly more time in proximity to the familiar call compared to the unfamiliar call and also showed shorter latencies to approach the familiar call than control birds. Increased emotional reactivity, i.e. propensity to express fear responses, was also found in T-treated chicks. Baseline heart rates recorded in a second group of T-treated embryos and control embryos did not differ, which suggests no effect of yolk testosterone on baseline arousal level. To our knowledge this is the first demonstration of the influence of prenatal exposure to testosterone on auditory learning.

Habituation to humans affects yolk steroid levels and offspring phenotype in quail

In the field as well as in the laboratory, human-generated stress responses are reduced in adult animals previously habituated to humans in comparison to non-habituated individuals. In birds, yolk steroid levels vary with maternal environment and condition. We tested the hypothesis that the experience of female birds with humans could affect yolk steroids levels and offspring phenotype. Two groups of Japanese quail, one habituated to humans (H) and a second non-habituated (NH), were exposed daily to brief human disturbances. We analysed egg quality, offspring growth, and offspring emotional reactivity. NH females produced eggs with less androgens (testosterone and androstenedione) and more immunoreactive progesterone compared to birds habituated to humans. NH females produced eggs with less yolk, heavier shell and chicks hatching later and being smaller as compared to habituated individuals. A lower emotional reactivity was found in young of NH females compared to young of H females. Thus, human disturbance of the mother triggered different effects on chick phenotype depending on previous experience of mother birds with humans. In addition, we describe for the first time the influence of environmental stimuli on yolk immunoreactive progesterone levels. Our results show that a relatively minor difference in behavioral habituation may have substantial effects on eggs and offspring. This has obvious implications for keeping and handling laboratory animals, for conservation biology and for animal welfare.

Influence of various early human-foal interferences on subsequent human-foal relationship

Whereas the way animals perceive human contact has been particularly examined in pet animals, a small amount of investigations has been done in domestic ungulates. It was nevertheless assumed that, as pet animals, non-aggressive forms of tactile contact were as well rewarding or positive for these species, even though the features of intraspecific relationships in pet animals and domestic ungulates may be to some extent different. We test here the hypothesis that horses may not consider physical handling by humans as a positive event. When comparing different early human-foal interactions, we found that early exposure to a motionless human enhanced slightly foals reactions to humans whereas forced stroking or handling in early life did not improve later human-foal relation. Foals that were assisted during their first suckling (e.g., brought to the dam's teat) even tended to avoid human approach at 2 weeks, and physical contact at 1 month of age. We argue that interspecies differences may exist in how tactile stimulation is perceived. It may be important for the establishment of a bond that a young animal is active in the process and able, through its behavioral responses, to help define what is positive for it. This way of investigation may have important general implications in how we consider the development of social relations, both within and between species.

Are 6-month-old foals sensitive to dam's influence?

A recent study has shown that gently handling dams in front of their few days old foals may strongly influence the development of human-foal relationships. In the present study, we test whether 6-month-old foals remain sensitive to their dams' influence. The study was performed on 16 foal-mare dyads, with half of the mares receiving positive contacts from the experimenter in presence of their 6-month-old foals (n = 8) whereas the other mares were not handled (n = 8). All foals were tested 15 and 30-35 days later under various conditions (reaction to a motionless human, approach test, saddle-pad tolerance test). We observe a positive effect of mare' handling on foals' reactions to humans but with a high interindividual variability, suggesting a higher effect of the foals' own behavioral characteristics at this age than at earlier stages.

Mothering during early development influences subsequent emotional and social behaviour in Japanese quail

The aim of the present study was to investigate the influence of mothers on the emotional reactivity and social behaviour in young precocial Japanese quail. We used a classical method of maternal deprivation. Ethological tests and observations analysed and compared the behaviour of young artificially raised quail to that of young raised by adoptive maternal quail. After separation from mothers, brooded young were more fearful (frightened easily) in the presence of humans (human-observer tests) and more neophobic in novel environments (open-field and hole-in-the-wall tests) than young raised artificially. As chicks rarely expressed fear during the brooding period, no differences related to mothering could be observed at that time. In separation tests, brooded chicks jumped significantly more frequently than non-brooded chicks and later, observations of groups revealed that brooded chicks remained closer to one another than non-brooded chicks. Social motivation of brooded chicks appeared to be higher. These results indicate that, during their first days of life, mothers influence the emotional and social behaviour of their young.