Effects of tryptophan and probiotic supplementation on growth and behavior in quail.

In laying hens, a diet supplemented with tryptophan (Trp) has been shown to affect their pecking behavior. However, unlike this positive effect, Trp is also involved in negative effects on behavior and stress through indolic pathways. Indole production can be reduced by probiotics (Pro), thus we hypothesized that Pro may prevent negative effects of Trp and increase beneficial effects on behavior in birds. Combined effects of Pro and Trp were also expected. To investigate the effects on behavior in birds of supplementing with a high level of Trp with or without Pro, Japanese quail were used because their behavior can be influenced by Pediococcus acidilactici, and they can be highly aggressive. Quails (n = 120) were assigned to 4 groups in a 2 × 2 factorial design for 55 d: C-C (control diet with usual Trp level, 0.3%; without Pro; n = 30), Trp-C (Trp: 2%; without Pro; n = 30), C-Pro (control diet; with Pro: 1 x 109 CFU/L P. acidilactici in drinking water; n = 30), and Trp-Pro (Trp 2%; with Pro; n = 30). Body weight was measured every week, and different tests were conducted to investigate behavioral characteristics of each quail. Contrary to our hypothesis, there was almost no interaction between Trp and Pro treatments. Tryptophan supplementation significantly (P < 0.05) reduced live weight up to 27 d, whereas Pro treatment had no effect. There was no significant difference between groups for tonic immobility variables (P > 0.05). The birds fed the high Trp diet spent significantly less time in the periphery of the open field than those fed the control diet and moved less in the arena during the social isolation test. Interindividual distances were significantly lower in males fed with Trp 2% than with the control diet, whereas Trp and Pro supplements interacted in females. The treatments did not affect sexual motivation in males. These results indicate that a high level of Trp reduced growth and appeared to enhance emotional reactivity in quails and that supplementing with Pro did not reduce these effects. In conclusion, feeding high Trp for 55 d cannot be recommended as a strategy to improve social behavior unlike effects observed in laying hens.

Influence of dietary strategy on progression of health and behaviour in mule ducks reared for fatty liver production.

Overfeeding in ducks is questioned because forced introduction of food into the animal and metabolic overload may induce damage to health and discomfort. In this context, the objective of our experiment was to measure the impact of dietary strategy on the progression of animal status evaluated through 28 health and behavioural indicators in ducks reared for fatty liver production. To do this, 320 ducks were forced-fed twice a day from 70 to 90 days of age including 10 days of overfeeding (87 to 96 days). They were divided into two groups differing in the feeding strategy during overfeeding period: a moderate feed intake (MI, an average of 376 g of maize flour per meal, n = 160 ducks) or at high feed intake (HI, 414 g/meal, n = 160 ducks). We evaluated 28 indicators related to Good feeding (n = 3), Good housing (n = 4), Good health (n = 10) and Appropriate behaviour (n = 11) principles, taken from the European Welfare Quality Consortium® at four stages: before overfeeding (BEF; 80 days), at the beginning (88 days), the middle (MID; 92 days) or the end of overfeeding (END; 96 days). Animals were slaughtered at 93 and 97 days to measure fatty liver weight at MID and END stages (n = 80 per group). The results showed that dietary strategy influenced the fatty liver weight at MID (+23% in HI v. MI group; P < 0;05) and END stage (+23%; P < 0.05). Assessment stage influenced 13 of the 28 indicators measured. Among these 13 indicators, (i) BEF differed from END stage for 7 indicators and (ii) the dietary strategy degraded all the indicators chosen to evaluate the Good feeding (2/2) principle, but had no effect on the indicators related to the Good health (0/4) principle while (iii) most of the indicators that evaluated Good housing (2/3) and Appropriate behaviour (2/4) principles were affected by an interaction between both factors. Our results suggest that (i) duck fattening status, including the fatty liver weight, and several welfare indicators progressed during the fatty liver production process; and (ii) feeding strategy influenced or even interacted with this progression.

Omega-3 polyunsaturated fatty acids provided during embryonic development improve the growth performance and welfare of Muscovy ducks (Cairina moschata).

The welfare of ducks can be affected by unwanted behaviors such as excessive reactivity and feather pecking. Providing long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) during gestation and early life has been shown to improve the brain development and function of human and rodent offspring. The aim of this study was to test whether the pecking behavior of Muscovy ducks during rearing could be reduced by providing LC n-3 PUFA during embryonic and/or post-hatching development of ducklings. Enrichment of eggs, and consequently embryos, with LC n-3 PUFA was achieved by feeding female ducks (n-3F) a diet containing docosahexaenoic (DHA) and linolenic acids (microalgae and linseed oil). A control group of female ducks (CF) was fed a diet containing linoleic acid (soybean oil). Offspring from both groups were fed starter and grower diets enriched with DHA and linolenic acid or only linoleic acid, resulting in four treatment groups with 48 ducklings in each. Several behavioral tests were performed between 1 and 3 weeks of age to analyze the adaptation ability of ducklings. The growth performance, time budget, social interactions, feather growth, and pecking behavior of ducklings were recorded regularly during the rearing period. No significant interaction between maternal and duckling feeding was found. Ducklings from n-3F ducks had a higher body weight at day 0, 28, and 56, a lower feed conversion ratio during the growth period, and lower reactivity to stress than ducklings from CF ducks. Ducklings from n-3F ducks also exhibited a significantly reduced feather pecking frequency at 49 and 56 days of age and for the whole rearing period. Moreover, consumption of diets enriched with n-3 PUFA during the starter and grower post-hatching periods significantly improved the tibia mineralization of ducklings and the fatty acid composition of thigh muscles at 84 days of age by increasing the n-3 FA content.

Environmental enrichment reduces behavioural alterations induced by chronic stress in Japanese quail.

Animals perceiving repeated aversive events can become chronically stressed. Chronic activation of the hypothalamic-pituitary-adrenal (HPA) axis can have deleterious consequences on physiological parameters (e.g. BW, blood chemistry) and behaviour (e.g. emotional reactivity, stereotypies, cognition). Environmental enrichment (EE) can be a mean to reduce animal stress and to improve welfare. The aim of this study was first, to assess the effects of EE in battery cages on the behaviour of young Japanese quail and second, to evaluate the impact of EE on quail exposed to chronic stress. The experiment involved quail housed in EE cages and submitted or not to a chronic stress procedure (CSP) (EE cages, control quail: n=16, CSP quail: n=14) and quail housed in standard cages and exposed or not to the CSP (standard non-EE cages, control quail: n=12, CSP quail: n=16). Our procedure consisted of repeated aversive events (e.g. ventilators, delaying access to food, physical restraint, noise) presented two to five times per 24 h, randomly, for 15 days. During CSP, EE improved quail's welfare as their stereotypic pacing decreased and they rested more. CSP decreased exploration in all quail. After the end of CSP, quail presented increased emotional reactivity in emergence test. However, the effect of EE varied with test. Finally, chronic stress effects on comfort behaviours in the emergence test were alleviated by EE. These results indicate that EE can alleviate some aspects of behavioural alterations induced by CSP.

CK2 accumulation at the axon initial segment depends on sodium channel Nav1.

Accumulation of voltage-gated sodium channel Nav1 at the axon initial segment (AIS), results from a direct interaction with ankyrin G. This interaction is regulated in vitro by the protein kinase CK2, which is also highly enriched at the AIS. Here, using phosphospecific antibodies and inhibition/depletion approaches, we showed that Nav1 channels are phosphorylated in vivo in their ankyrin-binding motif. Moreover, we observed that CK2 accumulation at the AIS depends on expression of Nav1 channels, with which CK2 forms tight complexes. Thus, the CK2-Nav1 interaction is likely to initiate an important regulatory mechanism to finely control Nav1 phosphorylation and, consequently, neuronal excitability.

Impact of high and low anxiety trait on object habituation and discrimination: evidence from selected lines of Japanese quail.

Compared to rodents, the relationship between anxiety and cognitive performances has been less studied in birds. Yet, birds are frequently exposed to stimulations that constitute a potential source of anxiety and can affect their adaptation to their living conditions. The present study was aimed at evaluating, in birds, the relationship between levels of anxiety and object habituation and discrimination with the use of Japanese quail lines divergently selected for a fear response, tonic immobility. Previous studies demonstrated that the selection programme has modified the general anxiety trait of the birds. The task consisted in 4 daily sessions of 8 successive presentations of the same object in the home cage of the quail in order to habituate each bird to the object. The observation that both quail with a high and a low anxiety trait progressively spent more time close to the object indicated that habituation occurred. Dishabituation was assessed during a single session of 8 presentations of a novel object. Only quail with a high anxiety trait exhibited significant discrimination. They spent significantly less time close to the novel object than to the habituated object. It is hypothesised that a high anxiety trait is associated with a more accurate processing of environmental cues or events resulting in better discriminative performances.

A higher inherent trait for fearfulness is associated with increased anxiety-like behaviours and diazepam sensitivity in Japanese quail.

This study tested whether lines of Japanese quails divergently selected for a fear response, the tonic immobility, might constitute a reliable bird model for studying anxiety. Previous studies demonstrated that the selection modifies the general underlying emotionality of the birds rather than exerting its effect only on tonic immobility. The behavioural effects of intraperitoneal injections of diazepam, an anxiolytic drug, were assessed in two lines of quail selected either for their short (STI) or long (LTI) duration of tonic immobility. Effects of diazepam were examined in two tests used for measuring emotionality in birds, the open field and the tonic immobility tests. After being placed in the centre of the open field, birds with a high emotionality (LTI quails) stayed longer in the centre of the apparatus than STI quail. Diazepam had anxiolytic effect in LTI birds as it increased the time spent in the outer area. This effect of diazepam appears to be selective because the drug has no effect on other behaviours such as distress calls or escape attempts. The drug has also no effect on the tonic immobility response in any of the two lines. These findings reveal an "anxiogenic" trait of LTI birds in the open field test that can be modulated by the administration of an anxiolytic drug. Therefore quails selected for LTI and STI represent a valuable model to study the mechanisms underlying anxiety in birds.

Identifying and monitoring pain in farm animals: a review.

One important objective for animal welfare is to maintain animals free from pain, injury or disease. Therefore, detecting and evaluating the intensity of animal pain is crucial. As animals cannot directly communicate their feelings, it is necessary to identify sensitive and specific indicators that can be easily used. The aim of the present paper is to review relevant indicators to assess pain in several farm species. The term pain is used for mammals, birds and fish, even though the abilities of the various species to experience the emotional component of pain may be different. Numerous behavioural changes are associated with pain and many of them could be used on farms to assess the degree of pain being experienced by an animal. Pain, as a stressor, is associated with variations in the hypothalamic-pituitary-adrenal axis as well as in the sympathetic and immune systems that can be used to identify the presence of pain rapidly after it started. However, most of these measures need sophisticated equipment for their assessment. Therefore, they are mainly adapted to experimental situations. Injuries and other lesional indicators give information on the sources of pain and are convenient to use in all types of situations. Histopathological analyses can identify sources of pain in experimental studies. When pronounced and/or long lasting, the pain-induced behavioural and physiological changes can decrease production performance. Some indicators are very specific and sensitive to pain, whereas others are more generally related to stressful situations. The latter can be used to indicate that animals are suffering from something, which may be pain. Overall, this literature review shows that several indicators exist to assess pain in mammals, a few in birds and very few in fish. Even if in some cases, a single indicator, usually a behavioural indicator, may be sufficient to detect pain, combining various types of indicators increases sensitivity and specificity of pain assessment. Research is needed to build and validate new indicators and to develop systems of pain assessment adapted to each type of situation and each species.

Long-term exposure to unpredictable and uncontrollable aversive events alters fearfulness in sheep.

Numerous studies have investigated the emotional effects of various acute, potentially alarming events in animals, but little is known about how an accumulation of emotional experiences affects fearfulness. Fearfulness is a temperament trait that characterizes the propensity of an individual to be frightened by a variety of alarming events. The aim of this study was to investigate a putative alteration of fearfulness in sheep repeatedly exposed to various aversive events. Forty-eight 5-month-old female lambs were used. Over a period of 6 weeks, 24 of them (treated group) were exposed daily to various unpredictable and uncontrollable aversive events related to predatory cues, social context and negative handling that can occur under farming conditions. The other 24 lambs (control group) were housed in standard farming conditions (predictable food distribution and group handling). Fearfulness (behavioural and physiological responses) was assessed before and after the treatment period by subjecting the lambs to three standardized tests: individual exposure to suddenness and then to novelty in a test arena, and group exposure to a motionless human in the home pen. As biomarkers of stress, leukocyte counts, heart rate and cortisol concentrations were measured in the lambs in their home pens. Before the treatment, the emotional responses of the groups did not differ. After the treatment, treated lambs approached the human less often, had less contact with the novel object and vocalized more than controls in individual tests, suggesting that long-term exposure to unpredictable and uncontrollable aversive events increases subsequent fearfulness in sheep. In addition, treated lambs had lower leukocyte counts, heart rate and cortisol levels, pointing to a chronic stress state. These findings suggest that increased fearfulness may be used as a sign of chronic stress in farm animals.

Minimising pain in farm animals: the 3S approach - 'Suppress, Substitute, Soothe'.

Recently, the French National Institute for Agricultural Research appointed an expert committee to review the issue of pain in food-producing farm animals. To minimise pain, the authors developed a '3S' approach accounting for 'Suppress, Substitute and Soothe' by analogy with the '3Rs' approach of 'Reduction, Refinement and Replacement' applied in the context of animal experimentation. Thus, when addressing the matter of pain, the following steps and solutions could be assessed, in the light of their feasibility (technical constraints, logistics and regulations), acceptability (societal and financial aspects) and availability. The first solution is to suppress any source of pain that brings no obvious advantage to the animals or the producers, as well as sources of pain for which potential benefits are largely exceeded by the negative effects. For instance, tail docking of cattle has recently been eliminated. Genetic selection on the basis of resistance criteria (as e.g. for lameness in cattle and poultry) or reduction of undesirable traits (e.g. boar taint in pigs) may also reduce painful conditions or procedures. The second solution is to substitute a technique causing pain by another less-painful method. For example, if dehorning cattle is unavoidable, it is preferable to perform it at a very young age, cauterising the horn bud. Animal management and constraint systems should be designed to reduce the risk for injury and bruising. Lastly, in situations where pain is known to be present, because of animal management procedures such as dehorning or castration, or because of pathology, for example lameness, systemic or local pharmacological treatments should be used to soothe pain. These treatments should take into account the duration of pain, which, in the case of some management procedures or diseases, may persist for longer periods. The administration of pain medication may require the intervention of veterinarians, but exemptions exist where breeders are allowed to use local anaesthesia (e.g. castration and dehorning in Switzerland). Extension of such exemptions, national or European legislation on pain management, or the introduction of animal welfare codes by retailers into their meat products may help further developments. In addition, veterinarians and farmers should be given the necessary tools and information to take into account animal pain in their management decisions.

Higher inherent fearfulness potentiates the effects of chronic stress in the Japanese quail.

There is considerable variability in the susceptibility of individuals to the adverse effects of chronic stress. In humans and other mammals, individual traits such as high anxiety are proposed as a vulnerability factor for the development of stress-related disorders. In the present study, we tested whether a similar behavioural trait in birds, higher emotional reactivity, also favours the occurrence of chronic stress-related behavioural and physiological dysfunction. For this, lines of Japanese quail divergently selected for a typical fear response in birds, the duration of tonic immobility, were subjected to unpredictable aversive stimulation over 2 weeks. Previous studies demonstrate that the selection program modifies the general underlying emotionality of the birds rather than exerting its effect only on tonic immobility. Interestingly, only birds selected for their higher emotionality exhibited significantly enhanced latency to first step and decreased locomotor activity in the open-field test after exposure to chronic stress compared to non-stressed control birds. This effect of chronic stress was selective for the tested dimension of bird emotional reactivity because there was no observed effect on the tonic immobility response. Moreover, chronically stressed birds selected for their higher emotionality exhibited significantly decreased basal corticosterone levels, a physiological marker of stress. These findings show that chronic stress is associated with changes in emotional reactivity and related physiological markers in birds. They also highlight emotional reactivity as an important predisposing factor for the occurrence of the adverse effects of chronic stress in birds.

Early visual experience of food does not appear to reduce subsequent feed neophobia in turkeys.

Turkeys may reduce their feed intake because of neophobia toward a new diet; however, their feeding behavior is not well known. The aim of this study was therefore to investigate the effects of diet color on behavior and feed intake in turkeys. For 2 wk, 2 groups of 1-day-old turkey chicks were fed diets varying in color but of the same composition: light-colored crumbles (LC group) or dark-colored crumbles (DC group). Both groups (total n = 144) were then fed a novel diet of green crumbles for the next 2 wk. On d 30, the original groups were each divided into 3 groups and received light, dark, or green pellets. We postulated that neophobia on d 30 would be reduced for chicks fed 1) green pellets compared with diets of other colors because of the effect of recent experience, and 2) a diet of a color that was previously encountered over the first 2 wk of life. Behavior and feed intake were measured on the days before and during each feed transition at 5 min after the changeover feed to observe the short-term reaction. On the first transition day, birds in the LC group decreased their feed intake significantly at 5 min, unlike birds in the DC group, which increased their feed intake. Exploratory behavior increased in both groups when they received green crumbles on the transition day, indicating a response to the color. The changeover to pellets induced a reduction in feed intake in all groups at 5 min, but, in line with our first hypothesis, behavioral changes were less pronounced in birds receiving green pellets. However, turkeys in the DC group did not eat more dark-colored pellets than those in the other groups, and turkeys in the LC group did not eat more light-colored pellets. In the present experiment, we conclude that previous visual experience did not reduce subsequent feed neophobia but that color continuity facilitated a diet change from one feed form to another.

Human handling and presentation of a novel object evoke independent dimensions of fear in Japanese quail.

Fear is a concept comprising several dimensions, but the nature of these dimensions and the relationships between them remain elusive. To investigate these dimensions in birds, we have used two genetic lines of quail divergently selected on tonic immobility duration, a behavioural index of fear. These two lines differ in their behavioural response to some, but not all, fear-inducing situations. In the present study, we investigated the contribution of human intervention in the differentiation between the two lines. To do this, fear responses towards a novel object were compared between lines in three conditions: (1) in the home cage without any human intervention, (2) in the home cage after human handling and (3) after placement in a novel environment by human handling. Fear behaviour differed between lines after human handling, with or without placement in a novel environment, but presentation of a novel object in the home cage without any human intervention induced similar fear responses in the two lines of quail. These results lead us to suggest that in quail, human intervention evokes a dimension of fear that differs from that evoked by sudden presentation of a novel object, in that these two dimensions may be selected independently.

The European experience in poultry welfare--a decade ahead.

Farm animal welfare is a major issue in Europe, which resulted in regulations and development of research dedicated to animal welfare, especially on standard poultry production, which is often considered as resulting in very poor welfare. The effect of selection is also often questioned. Indeed, capacities of adaptation have been very little considered during the first years of commercial selection and thus have been reduced. Nowadays, a much greater importance is given to welfare-related traits and genomic selection should alleviate the need for their measurements in the short-term. However, the choice of the fittest selection criteria is still to be made. Because behavioral traits are highly dependent on environment, general reactivity may be more efficient. For example, selection against undesirable behavior such as feather pecking has been proven to be efficient, but selection for reduced mortality rates in collective cages proved to be preferable. Most often, selection should not exacerbate extreme values, which are most often detrimental, as in the case of social motivation, which, when increased to too large of an extent, results in increased aggressivity. Moreover, a general propensity will not result in overall improvement; for example, reducing fearfulness has positive effects but does not modify response to social stress. Detrimental effects on other traits may also be observed: although genetic resistance to diseases should increase animal welfare, it may also result in increased frequency of silent carriers and in turn to human transmission. Indeed, an optimum must be found. Studying lines selected for or against these traits will be of great help to choose the best strategy of selection. Another and longer term concern should be on links with other production traits but also on sustainability, which will probably be of greater importance in the coming years.

Subdivisions of the arcopallium/posterior pallial amygdala complex are differentially involved in the control of fear behaviour in the Japanese quail.

Growing evidence suggests that the arcopallium/posterior pallial amygdala plays a major role in the control of fear behaviour in birds. This brain region comprises several subdivisions, but no direct evidence is available about its functional parcellation. The aim of the present study was to investigate the relative involvement of two subdivisions of the arcopallium/posterior pallial amygdala complex in four classical tests of fear in quail: the presentation of a novel object, the 'hole-in-the-wall', 'open-field' and tonic immobility tests. Bilateral electrolytic lesions damaging the posterior part of the arcopallium/posterior pallial amygdala resulted in an increase in fear behaviour in the 'open-field' test, whereas quail with lesions damaging the anterior part of the arcopallium displayed a decrease in an 'overall fear score', compared to quail with bilateral nidopallium or sham lesions. The differential involvement of the anterior and posterior parts of the arcopallium/posterior pallial amygdala in fear behaviour is discussed in view of the known connections between the arcopallium/posterior pallial amygdala complex and brain regions considered to be limbic in nature.

[Colchicine intoxication in four elderly patients: how to prevent it?]. / Risque d'intoxication à la colchicine chez les personnes âgées et moyens de prévention: à propos de quatre observations.

INTRODUCTION: In France, unlike other countries, the use of colchicine is preferred to other anti-inflammatory drugs for the treatment of gout. CASE REPORTS: We report a case series of four elderly patients (range from 72 to 83 years of age) who presented with colchicine intoxication, all notified to the Basse-Normandie pharmacovigilance centre in 2007. For each patient, one or more risk factors were identified: renal failure, high initial dosage, absence of laboratory monitoring. CONCLUSION: It would be useful to establish specific guidelines for colchicine use in the elderly population.

Forty-eight-hour cycle sequential feeding with diets varying in protein and energy contents: adaptation in broilers at different ages.

Sequential feeding is a cyclic feeding program with 2 diets for 1 or several days used to induce lower feed costs or to improve welfare quality. The aim of the present study was to investigate the effects of energy [2,800 (E-) and 3,200 kcal/kg (E+)] and protein [230 (P+) and 150 g/kg (P-)] content on daily feed intake and growth in 900 male broiler chickens, and to compare these results with standard feeding (CP = 190 g/kg and ME = 3,000 kcal/kg). Sequential feeding was carried out during 48-h cycles in 2 periods (period 1 = 10 to 17 d of age, period 2 = 18 to 29 d of age). Four treatments were compared during periods 1 and 2: 1) complete diet (C), 2) alternation of diets varying in CP (SP = P+ followed by P-), 3) in energy (S(E) = E- followed by E+), 4) in protein and energy contents (S(EPA) = P+E- followed by P-E+). A fifth treatment (S(EPB)) used an alternation in protein and energy contents during period 2 only. All chickens received the same feed during the finishing period (30 to 35 d of age). Feed intake was similar with sequential feeding and complete feed, but in proportion to total feed intake, chickens overconsumed high energy feeds (E+ and E+P-) during each period, and P- only for period 2 (P < 0.01). During period 2, overconsumption was greater with S(EPA) than S(EPB) (P < 0.01). Weight gain was similar for all treatments during period 1. At 35 d of age, S(E) chickens were heavier than S(EPA) and S(EPB) (P < 0.01). Feed to gain ratio was similar for all treatments for period 1 and increased for S(P), S(EPA), and S(EPB) compared with C and S(E) for period 2 (P < 0.01). Walking ability, carcass conformation, breast yield, and abdominal fat did not differ between treatments, but ultimate pH of breast meat was improved with S(P). In conclusion, growth and slaughtering performances similar to standard feeding can be reached with 48-h cycle sequential feeding using diets varying in protein and energy contents.

Sequential feeding with variations in energy and protein levels improves gait score in meat-type chickens.

Feeding broilers by alternating different diets for 1 or 2 days is known as sequential feeding, and it possibly reduces leg problems since it slows down early growth and may enhance general activity. The present study compared continuous feeding with a standard diet (C: metabolisable energy = 12.55 MJ/kg, crude protein = 190 g/kg) with alternations of a high-energy/low-protein diet (E+P-:+7% ME; -20% CP) and a low-energy/high-protein diet (E-P+: -7% ME,+20% CP) and investigated its effects on growth, behaviour and gait score in 352 male Ross broiler chickens. Sequential feeding was carried out during ten 48-h sequential-feeding cycles from 8 to 28 days of age. Three treatments were compared: complete diet (C) and two alternations of diets varying in protein and energy contents (S1: E+P- followed by E-P+; and S2: E-P+ followed by E+P-). Chickens received the same feed during the starter and finisher periods (0 to 7 and 29 to 38 days of age). Body weight (BW), feed intake, general activity and gait score, bone quality and carcass conformation were measured to evaluate leg condition and general performance. Sequential feeding significantly reduced BW at 28 days of age (S1: -9.1%; S2: -3.7%/C group; P < 0.05) and S1 were lighter than S2. In both sequential groups, time spent standing increased (C: 28%; S1:33%; S2: 35%; P < 0.05) and leg abnormalities decreased (mean gait score: C: 2.61; S1: 2.45; S2: 2.38; P < 0.02). This improvement was not related to changes in bone quality. BW at slaughter was impaired in Group S1 only, and the feed conversion ratio throughout the rearing period was not significantly impaired by sequential feeding. However, abdominal fat was higher in the S2 group. Sequential feeding using diets varying in energy and crude protein can be a useful method of reducing leg problems in broilers since it improves gait score without impairing growth performance when used as early as 8 days of age and up to not less than 8 days before slaughter in order to compensate for reduced growth. This improvement can be explained by reduced early growth and enhanced motor activity. However, it appears that the low-energy diet should be given first in order to avoid a reduction in BW at slaughter.

Effects of various energy and protein levels during sequential feeding on feed preferences in meat-type chickens.

Short-term feed preferences were studied in individually caged chickens fed sequentially in order to understand a previously described imbalance in the intake of diets offered. Sequential feeding (SF) was carried out for four 48 h cycles in male broiler chickens. The diets varied in energy (2800 (E-) and 3200 kcal/kg (E+)) and protein (230 (P+) and 150 g/kg (P-)) contents. SF was compared to standard feeding (C) (3000 kcal/kg ME and CP = 190 g/kg). In experiment 1, three treatments were used: C, SE (E- followed by E+) and SE' (E+ followed by E-). Four treatments were used in experiment 2: C, SP (P+ followed by P-), SE and SEP (P+E- followed by P-E+). Total feed intake was measured during the SF period. After this, short-term preferences were evaluated with a choice test on chickens previously fed with the same feeds during the SF period (experienced birds) and in C chickens (naïve birds). In both experiments, total feed intake was similar among treatments and the percentage of each feed consumed was not significantly different from controls (50%). In experiment 1, SE and SE' chickens over-consumed E+ and under-consumed E- diets only during the first 15 min of the fourth cycle. The choice test indicated that experienced chickens preferred E+, while naïve chickens preferred E-. Similarly, in experiment 2, chickens over-consumed E+ and E+P- during the first 15 min of the fourth cycle, but the intake of diets varying in protein content was not different from controls. During the choice test, as in experiment 1, experienced chickens preferred E+, while naïve chickens preferred E-. There was a slight preference for the protein-poor diet in naïve birds and there was no preference in the diet varying in both protein and energy contents. Experience modified choice between feeds varying in energy content but not in protein. When feeds were known, preference for energy affected the feed intake immediately after switching from one diet to the other, although lower with the diet also varying in protein, it did not influence the total intake of each diet. Interactions between the nutritional properties and sensorial cues of feed could explain these results.

Genetic selection on a behavioural fear trait is associated with changes in heart rate variability in quail.

This study investigated whether genetic selection on a divergent behavioural trait of fearfulness (tonic immobility duration) was related to changes in the nervous control of the heart. Quail selected for either long or short tonic immobility (LTI or STI, respectively) duration was compared with an unselected control line (CTI). The autonomic control of the heart was assessed by heart rate variability analysis and pharmacological blockades. Quail were surgically fitted with a telemetric device. Heart rate before injection did not differ between the three lines. The vagal-sympathetic effect (VSE) at rest differed significantly from 1 in CTI and STI quail, suggesting that parasympathetic activity was dominant. In LTI quail, VSE did not differ from 1, suggesting a balance between parasympathetic and sympathetic activities. The intrinsic heart rate reached after the successive injections of propranolol and atropine did not differ between lines and was higher than the heart rate at rest in STI, which was in line with results of VSE at rest. After atropine injection, the sympathetic activity indicated by the low-frequency power was lower in CTI than in the two selected quail. After propranolol injection, the parasympathetic activity indicated by the root of the mean squares of successive differences and the high-frequency power was higher in STI than in CTI and LTI quail. Selection on tonic immobility duration thus appears to be associated with changes in the sympathovagal control of the heart, which may influence behavioural responses to stressful situations.