Tonic Immobility Research Articles

Commercial hatchery processing may affect susceptibility to stress in laying hens.

Directly upon hatching, laying hen chicks are exposed to multiple stressful events during large-scale hatchery processing, which may affect their later coping abilities. Commercial hatchery chicks (HC) were compared to chicks that were incubated and hatched simultaneously under calm conditions (CC). After being raised under similar, non-stressful conditions for 36 days, all chicks were exposed to a series of stressors: transportation and introduction into a novel environment followed by a regrouping event in order to characterize long-lasting consequences of hatchery treatment. Tonic immobility, corticosterone levels, and peripheral body temperature were used to assess reactions to the stress events. Tonic immobility was not affected by treatment but was significantly reduced in CC after transport. Corticosterone levels did not differ between treatments when assessed two days before and two days after regrouping. Comb temperature was significantly higher in HC following regrouping, indicating stress-induced hyperthermia. Furthermore, comb temperature dropped more following blood sampling in HC than in CC, indicating a stronger autonomic response to acute stress. In conclusion, the results suggest possible long-term negative effects of commercial hatchery processing, compared to hatching under silent and less stressful conditions, on the coping ability of laying hens to later stressful experiences.

Impact of mechanical vs. manual catching on stress, fear, and carcass quality in slower growing broilers

ABSTRACT This study evaluated manual and mechanical catching methods on slower growing broiler chickens on the day of processing. Ten catching events, five mechanical and five manual, were evaluated for animal welfare and an additional set of 241 catches, 128 manual and 113 machine, were analyzed to determine the effect on carcass quality. No significant difference in serum corticosterone concentration (CORT) was found between the catching methods (p = 0.9). Pre-catching CORT (15.07 ± 2.24) was significantly lower than post-catching (25.41 ± 2.22) (p < 0.001). Manually caught broilers had four times greater odds of tonic immobility (TI) than mechanically caught birds (OR 4.0, 95% CI: 1.54–10.54) (p < 0.001). Birds also had 77% lower odds of TI before being caught than after, irrespective of catching method. Manually caught birds had 19% greater risk of bruised wings (p < 0.05) and 23% greater risk of bruised legs (p < 0.05). Lower odds of TI and decreased risk of injury in the machine caught birds indicate improved welfare and carcass quality compared with manual catching. Overall, machine catching was found to improve welfare and carcass quality in these slower growing broilers.

Effect of genotype on growth, fear-related behaviours, and walking ability of FUNAAB Alpha broiler chickens

The FUNAAB Alpha broiler, a tropical chicken breed developed in Nigeria, has three genotypes which are normal feather (NF), naked neck (NN), and frizzle feather (FF). This 56-day study investigated the effect of genotype on growth, fear-related behaviours, and walking ability of FUNAAB Alpha broiler chickens. Two hundred and four (204) chickens (68 NF, 68 NN, and 68 FF chickens; 34 males and 34 females per genotype) were used for the experiment. Body weight and growth rate were measured on days 27 and 56. The level of fear using the tonic immobility test (TI) on days 23 and 51, and emergence from a dark box on days 25 and 53 were measured. Walking ability was assessed using the latency to lie test on day 54. There was a genotype effect on body weight on days 27 and 56 (p = 0.02 and p = 0.01, respectively) and growth rate from days 1–27 and days 1–56 (p = 0.02 and p = 0.03, respectively). Of the three genotypes, the NN chickens were lighter in body weight, while the NF and FF had similar body weights on days 27 and 56 (p = 0.64 and p = 0.85, respectively), and growth rate from days 1–27 (p = 0.79). The male chickens were heavier on days 27 and 56 (p = 0.04 and p = 0.04, respectively) and had a better growth rate from days 1–27 (p = 0.03). The duration of tonic immobility on days 23 and 51 was similar in all three genotypes. The latency to emerge from a dark box on day 25 was not affected (p = 0.70) by genotype, but it took the NF chickens a longer time (138.20 ± 18.70 s) to emerge from the dark box on day 53. The walking ability of the birds was not affected (p = 0.83) by the genotype. However, male chickens had better (p = 0.01) walking ability by standing for a longer time than the females during the latency to lie test. In conclusion, the NF and FF chickens were heavier than the NN on days 27 and 56, and the NN and FF chickens were less fearful than the NF chickens on day 53. The FF genotype is recommended for meat production due to its better growth and less fearfulness.

Using shame to extend Martin Conway’s self-memory system

ABSTRACT We extend Conway’s self-memory system by adding theory and data from shame, an emotion that disrupts the internalised ideals of society needed for a positive self-concept. The event that caused 273 undergraduates their greatest amount of shame was analyzed; 66% were not very negative except for producing shame. Ratings of post-event effects, including two measure of self (self-perceived weakness, and centrality to identity) and four clinical symptoms (intrusions, avoidance, anxiety, and depression), were attributed separately to the remembered event, behaviour during the event, and shame from the event. The effects of shame were generally as large as the those of the event and larger than those of the behaviour, demonstrating the importance of shame’s effects. The Tonic Immobility Scale (TIS), which measures tonic immobility (i.e., freezing), was obtained for the event that produced the most tonic immobility but that was not the event that caused the most shame. The post-event symptoms measured on the event that caused the most shame and the TIS correlated highly, suggesting that shame and tonic immobility may belong to a cluster of phylogenetically conserved submissive defensive mechanisms that could account for effects currently attributed to goals in self-memory systems.

Efficacy of a brief web-based tonic immobility psychoeducation intervention among trauma-exposed adults: A randomized clinical trial.

Tonic immobility (TI) is a defensive response that may occur during traumatic events. Although TI is adaptive in certain circumstances, it has been shown to contribute to increased trauma-related symptoms and poorer recovery. However, current frontline treatments for posttraumatic stress disorder (PTSD) have not focused significant attention on the experience of TI. Thus, the aim of this study was to develop and test the impact of a brief TI-focused psychoeducation (TIP) intervention on posttraumatic cognitions and PTSD symptoms relative to a health education control intervention. The sample included 46 adults with elevated PTSD symptoms who endorsed prior TI episodes. After providing informed consent, participants were randomly assigned to either the active or control intervention and completed self-report questionnaires including the tonic immobility questionnaire (TIQ-R), Life Events Checklist for DSM-5 (LEC-5), Posttraumatic Stress Checklist for DSM-5 (PCL-5), Posttraumatic Cognitions Inventory (PTCI), and Positive and Negative Affect Schedule (PANAS) at baseline, 1-week, and 1-month follow-up assessments. Results from linear mixed effects models indicated that participants in the TIP conditionreported significantly larger reductions in posttraumatic cognitions and PTSD symptoms at 1-week, ds = 0.48 and 0.84, respectively, and 1-month, ds = 0.67 and 0.74. The findings suggest that TIP is a promising intervention that may be used to reduce posttraumatic cognitions and PTSD symptoms associated with TI. Given the ease of access, TIP could be used as a standalone intervention or as an add-on to existing evidence-based treatments for PTSD.

Why fake death? Environmental and genetic control of tonic immobility in larval lacewings (Neuroptera: Chrysopidae).

Tonic immobility is a passive antipredator strategy employed late in the predation sequence that may decrease individual mortality in prey animals. Here, we investigate how energetic state and genetic predisposition influence antipredator decision-making in green lacewing larvae, Chrysoperla plorabunda (Fitch), using simulated predatory encounters. We demonstrate that tonic immobility is a plastic response influenced by energetic resource limitation. Larvae exposed to 1 or 2 days of food deprivation initiate tonic immobility more often and with less physical provocation than individuals fed ad libitum. Recently molted individuals exposed to food deprivation, the individuals most energetically challenged, engage in tonic immobility at a higher rate than any other group. We also find that variation in antipredator strategy between individuals is partly the result of within-population genetic variation. We estimate the propensity to enter tonic immobility to have a broad-sense heritability of 0.502. Taken together our results suggest that larval lacewings under energetic stress are more likely to engage in tonic immobility. Yet, energetic state does not explain all within-population variation, as individuals can have a genetic predisposition for tonic immobility.

Training for a cognitive judgement bias task does not affect fear or telomere shortening in laying hens

For behavioural tests such as the cognitive judgement bias task (JBT), animals usually undergo weeks of training involving various elements, such as handling, social isolation and learning the task. These may influence their affective state and other welfare indicators. Here, we investigated the effects of training for a JBT on fear-related behaviour in laying hens and a potential welfare indicator – telomere shortening. Hens were trained for a JBT (N = 16, across 2 batches), or kept as controls (N = 16, across 2 batches) that received no training or training-related handling. Hens that reached the learning criterion (N = 14) were tested in six JBT test sessions. Before and after the trained hens received JBT training, blood was collected from all hens, and they were assessed for fear-related behaviour by being subjected to open field, human approach, and tonic immobility tests. Relative telomere lengths (RTL; i.e., ratio of telomeric repeats versus a single copy control) were obtained from blood samples with a quantitative real-time polymerase chain reaction (PCR) method. As anticipation of the JBT sessions could affect the JBT outcome, we also recorded behavioural indicators of anticipation prior to each JBT test session. Except for an increased latency to first step in the open field test after training in the trained hens (t = 3.1, df=28, P = 0.012; conditional R2=0.59), no other fear-related behaviour significantly differed in either group (P > 0.05) and RTL was not affected. In addition, none of the anticipation indicators predicted the JBT test outcome. Contra to our hypotheses, welfare-related aspects may not be strongly affected by the JBT training. However, the enriched housing of the hens from both treatments might have minimised the effect of training on fear and telomere shortening, or training may have affected indicators other than the ones we investigated. We conclude that because JBT training and testing does not affect fear assessment and telomere shortening outcomes in hens housed in enriched housing conditions, the same individuals can be used in welfare assessments involving similar assessments. Our results also suggest that the JBT itself may be robust against the temporary affective states associated with anticipation.

Indicators of thermal comfort and nitrogen digestibility as a function of digestible arginine: lysine ratios in the diet of laying Japanese quails raised in hot weather

The objective with this study was to determine the influence of the digestible arginine: lysine ratio in the diet of laying Japanese quails raised in hot weather on the physiological variables of thermoregulation, time in tonic immobility, behavior and nitrogen utilization. A total of 240 laying quails (Coturnix coturnix japonica) with 40 weeks of age were used in a completely randomized design with five treatments and six replications containing eight quails per experimental unit. The studied digestible arginine: lysine ratios were 110%; 120%, 130%, 140% and 150%, for 63 days divided into three periods of 21 days each. There was a quadratic effect (p < 0.05) for the variables average surface temperature, average body temperature, core to surface thermal gradient, ambient to surface temperature gradient observed in the morning. In the afternoon, a quadratic effect (p < 0.05) of the arginine: lysine ratio was observed for variables average surface temperature, average body temperature, core to surface thermal gradient, ambient to surface thermal gradient, back temperature, head temperature and respiratory frequency. There was no significant effect (p > 0.05) of arginine: lysine ratios on the frequency of behaviors, except drinking and panting (p < 0.05), for which 130% ratio provided the lowest frequencies of these behaviors. There was a quadratic effect (p < 0.05) for the parameters of nitrogen retention, nitrogen excreted and nitrogen retention efficiency. Nitrogen intake and excreta moisture were not influenced by the different relationships studied (p > 0.05). The 130% arginine: lysine ratio corresponding to 0.131 g/kg/feed of arginine improves physiological responses related to thermoregulation and decreases the expression of behaviors correlated to heat stress, also meeting the best estimated ratio for nitrogen retention in the diet of quails laying Japanese raised in hot weather.

Associations of range use with individual behaviour, clinical welfare indicators, fear response and gastrointestinal characteristics of two laying hen hybrids

Access to an outdoor range provides laying hens with increased space and improved opportunities for performing natural behaviours. However, not all hens utilise the range to the same extent, and this may be associated with the welfare of the individual hen. The aim of this study was to assess if extent of range use was associated with several clinical welfare indicators, time budgets, measures of tonic immobility and gastrointestinal characteristics. One hundred twenty focal individuals (Bovans Brown, n = 60; Dekalb White, n = 60) randomly chosen from 12 pens of 100 hens (10 hens from each pen) were housed in accordance with the EU organic standards. Clinical welfare indicators including plumage condition, foot health, keel bone damage and body weight were assessed upon arrival at 18 weeks of age and again at 23, 28, 33 and 38 weeks of age. Over five three-day periods at corresponding weeks, hens received individual back marks for identification and behaviour was recorded by instantaneous scan sampling from 8:30–15:30 in the house and on the range. Behaviour recorded included comfort behaviours, drinking, dust bathing, eating, foraging, locomotion, nest use, pecking, perching, resting and standing. Frequency of passes through the pophole and duration of time outdoors were also determined through video observations. At 18 weeks of age a tonic immobility test was performed and number of inductions, latency to first head movement after induction and the duration of tonic immobility were recorded. At the end of the study (38 weeks of age), gastrointestinal tract morphology and contents were assessed. Individual range use varied, with hens differing in time spent on range, number of exits and consistency in these measures over time. Extent of range use was not associated with clinical welfare indicators nor fear levels as assessed by a tonic immobility test. Hens’ time budgets differed depending on where they spent most of their day, with hens utilising the range to a greater extent generally being more active (duration on range: foraging: P < 0.001, standing: P = 0.005; number of exits: locomotion: P < 0.001). Hens that utilised the range to a greater extent likely consumed more forage, as evident by the greater weight of pasture found in their crop and gizzard (P < 0.001), contributing to more developed gastrointestinal organs including the crop (duration on range: P = 0.004), gizzard (P < 0.001), and proventriculus (duration on range: P = 0.014). To conclude, the fear level and clinical welfare condition of the hens were not associated with extent of range use, unlike the time budgets and gastrointestinal characteristics.

Differences in innate fear behaviour in native Japanese chickens

ABSTRACT 1. Comprehensive knowledge of innate fear in chickens has important implications for understanding the adaptation of native Japanese chickens in modern production and behavioural changes caused by modern breeding goals. Innate fear behaviour seen in chicks from six native Japanese chicken breeds;, Ingie (IG), Nagoya (NAG), Oh-Shamo (OSM), Tosa-Jidori (TJI), Tosa-Kukin (TKU) and Ukokkei (UK), were compared with those in two lines of White Leghorn (WL-G and WL-T) in tonic immobility (TI) and open field (OF) tests. 2. TI and OF tests were conducted for 267 chicks at 0-1 days of age in the eight breeds. Raw data for four TI traits and 13 OF traits were corrected for environmental factors. Breed differences were analysed by the Kruskal–Wallis test followed by the Steel Dwass post hoc test. Principal component (PC) analyses were conducted. 3. The results showed that OSM was the least sensitive to fear in both the TI and OF tests. The WL-G birds showed higher sensitivity to TI fear but lower sensitivity to OF fear. The PC analysis of OF traits classified the tested breeds into three groups: least (OSM and WL-G), moderate (IG, WL-T, NAG, TJI and TKU) and most sensitive (UK).

Tonic Immobility as a Defensive Trauma Response to Rape: Bridging Public Health and Law.

There is widespread scientific evidence that validates tonic immobility (TI) as part of the trauma response in victims of rape, and criminal justice practitioners are increasingly trained in trauma-informed approaches. Yet, legal and policy definitions of consent do not fully recognize TI during the incident as evidence of nonconsent. Using a systematic review of U.S. law and policy regarding sexual violence and consent, this paper analyzes the substantial legal reform of rape law and definitions of consent, suggesting ways to further integrate TI into existing law and legal practices to improve public health approaches and justice responses for victims.

Polyrhachis femorata (Hymenoptera: Formicidae) habitat and colony defensive immobility strategy

Many animal species ‘play dead’ or feign death (in some cases called tonic immobility) as a defence strategy against predators, including some ants, although triggers and durations are poorly understood. We repeatedly observed such death-feigning behaviour in Polyrhachis femorata ants that occupied pygmy-possum nest boxes deployed on Kangaroo Island following the 2019–2020 bushfires that burnt half of the island. Most of the 759 bat and pygmy-possum boxes (901 cavities) were on burnt ground. In 3312 box cavity checks on 13 diverse properties during monitoring visits, 28 of 40 P. femorata records (first for South Australia) occurred in unburnt Critically Endangered Narrow-Leaf Mallee Woodland community, seven in adjacent mallee community containing narrow-leaf mallee, three in cup gum unburnt habitat, and two in one box on burnt ground. Fire may have affected the abundance and re-establishment of the species. Polyrhachis femorata engages in a surprising defensive immobility strategy in boxes, since it is not only undertaken by individuals facing a potential predator, but also by entire colonies. The death-feigning behaviours were complemented by plugging box entrances. Nest boxes may be used to study this mysterious behaviour in this poorly known species, although frequent observation could lead to nest abandonment by the ant.

A review of tonic immobility as an adaptive behavior in sharks

A review of tonic immobility as an adaptive behavior in sharks

Effect of transportation distance on the physiological condition and carcass traits of kampong chickens

This research aimed to investigate the effect of transportation distance on the physiological conditions and carcass traits of kampong chickens. Two hundred and twenty-five male kampong chickens were transported for distances of 30 km, 60 km, and 90 km, departing from three villages. Their physiological conditions were observed for up to 12 hours after having reached the final destination, and they were slaughtered after 45 minutes of lairage. The results showed that the transportation distance had a minor influence on the male kampong chickens' physiological conditions on arrival and on resulting carcass traits. Decreased oxygen consumption and metabolism rates were observable only eight hours after the rest period, without further effects on body temperature, tonic immobility, and blood triglyceride levels. There were no significant changes in live shrink, liveability, and carcass production from various transportation distances. However, a significant percentage increase in live shrink, accompanied by a significant decrease in visceral weight, was noted after transportation distances above 60 km. There was a significant decrease in the percentage of drumstick weight and a minor decrease in overall carcass quality, derived from bruising on the thighs. No significant changes were noted in graded carcass quality, meat water-holding capacity, pH, lactic acid, or water content. It was concluded that transportation distances up to 90 km were physiologically tolerable to kampong chickens, imposing minor negative impact on carcass traits.

Increased duration of laser environmental enrichment increased broiler physical activity and pen-wide movement without altering tibia measurements

Inactivity and leg disorders negatively impact broiler welfare. Enrichment designed to increase barn complexity may encourage physical exercise. The study aim was to implement a second-generation laser enrichment device, previously shown to increase broiler activity, for extended periods of time and to measure behavior and tibia quality. A total of 1,360 Ross 708 broilers in 40 pens of 34 were assigned to laser enrichment or control (no laser enrichment) for 49 d. Seventy focal birds were randomly selected on d 0 for individual behavior analysis. Laser-enriched birds were exposed to 6-min laser periods 4 times daily. A 3-min novel object test was performed on all pens and tonic immobility was induced on 1 bird/pen on wk 1 and 6. Focal bird time budget and walking distance and pen-wide laser-following behavior and movement were obtained during laser periods d 0 to 8 and 1 d/wk through wk 7. Right tibias were collected from focal birds on d 49 for dual energy x-ray absorptiometry and bone breaking analysis. Time spent active during laser periods was increased on d 3, 6, and 8 and wk 2 to 3 in laser-enriched vs. control focal birds (P=0.04). Time at the feeder was increased in laser-enriched focal birds on d 0, 3 to 4, and 8 and wk 2 and 4 (P < 0.01). Distance walked during laser periods was increased in laser-enriched focal birds on d 1, 3 to 5, 8, and wk 2 compared to the control (P < 0.01). Pen-wide movement was increased on d 0, 2, 4 to 8, and wk 1 to 5 and 7 in laser-enriched vs. control birds (P < 0.01). More laser-enriched broilers were within 25 cm of the novel object at 1 min 30 s than the control (P=0.03), and latency to approach the novel object was reduced in both treatments at wk 6 compared to wk 1 (P < 0.01). Tonic immobility duration was increased by 123 s on wk 6 compared to wk 1, regardless of treatment (P < 0.01). Daily laser enrichment for extended periods increased bird activity without inducing fearfulness or altering tibia measures.

Differences among domestic chicken breeds in tonic immobility responses as a measure of fearfulness.

One priority for animal welfare is for animals to experience less fear, especially during human contact. For domestic animals, breeds that are less fearful may provide genetic resources to develop strains with improved welfare due to lower susceptibility to fear. Genetic predispositions inherited in these breeds might reflect the large diversity of chicken breeds. The goal of the present study was to systematically test a diverse group of chicken breeds to search for breeds that experience less fear. Nineteen chicken breeds from commercial hybrid lines, native layer-type, meat-type and dual-purpose breeds, ornamental breeds as well as bantam breeds were tested in a standardized tonic immobility (TI) test. Chickens were manually restrained on their back, and the time to first head movement and first leg movement, the duration of TI, as well as the number of attempts needed to induce TI were measured. The TI response differed among chicken breeds (p≤0.001) for naïve, mature hens. The median number of attempts required to induce TI ranged from 1 to 2 and did not differ significantly among breeds. Median durations were much more variable, with Lohmann Brown showing shortest durations (6 s, 12 s, 58 s for time to first head movement, first leg movement and total duration of TI, respectively). In contrast, medians reached the maximum of 600 s for all three measures in German Creepers. Repeated tests on the same individuals did not affect attempts needed to induce TI nor TI durations. Breeds clustered into two main groups, with layer-type native breeds and ornamental breeds having longer TI durations, and bantam, dual-purpose and meat-type native breeds having shorter TI durations. Our findings provide evidence for substantial variation of fearfulness among breeds. This variation could be linked to the intended use during the breed's specific history. Knowledge and quantitative measurement of these behavioural responses provide the opportunity to improve welfare through selection and future breeding.

Effect of silvopasture system on fearfulness and leg health in fast-growing broiler chickens.

A silvopasture system intentionally integrates trees, forages, and livestock, allowing dual land use. These systems can provide high-quality habitat for broiler chickens; however, such systems have not been widely adopted by the broiler industry in the United States. The objective of this study was to examine the effect of silvopasture versus open pasture access on fearfulness and leg health in fast-growing broiler chickens. A total of 886 mixed-sex Ross 708 chicks in Experiment 1 (Exp 1) and 648 chicks in Experiment 2 (Exp 2) were housed in coops and had access to 16 (Exp 1) or 12 (Exp 2) 125m2 silvopasture plots (x̄ = 32% canopy cover) or open pasture plots (no canopy cover) from day 24 of age. Fearfulness was measured using a tonic immobility test (tonic immobility duration), and leg health was assessed by quantifying footpad dermatitis, hock burns, gait, and performing a latency-to-lie test on days 37-39 of age. Birds in the silvopasture treatment were less fearful than birds in the open pasture treatment. Overall, birds in both silvopasture and open pasture systems had excellent leg health. Silvopasture birds had lower footpad dermatitis scores than open pasture birds. Silvopasture birds tended to have worse gait than open pasture birds in Exp 1, but not in Exp 2. Hock burn scores and latency-to-lie did not differ between treatments in Exp 1 or Exp 2. Raising birds in silvopasture reduced fear and improved footpad health compared to birds raised in open pastures, which indicates that silvopasture systems provide some benefits for affective state and leg health in fast-growing broilers.

Fearfulness in commercial laying hens: a meta-analysis comparing brown and white egg layers

High fearfulness in commercial laying hens can negatively affect production parameters and animal welfare. Brown and white egg layers differ in several behavioral characteristics, though reported differences in fearfulness are inconsistent. A meta-analysis was conducted to determine whether there are systematic differences in measures of fearfulness between brown and white layers. Twenty-three studies that examined either 1 or both of 2 behavioral tests were included: tonic immobility (TI) (longer duration=higher fearfulness, 16 studies) and novel object (NO) test (lower approach rate=higher fearfulness, 11 studies). The 2 tests were analyzed separately. TI analyses: A generalized linear mixed effect model (GLMM) with a lognormal distribution was fitted to describe the data with experiment nested in study as a random effect. Explanatory (X) variables were considered through backward selection, where potential X-variables included color (brown vs. white layers), decade (1980s, 2000s, 2020s), age (prelay vs. in lay), genetic stock (hybrid vs. grand-/parent stock), and methodology (back vs. side position). NO test analyses: univariable GLMMs with a beta distribution were fitted with approach rate as the Y-variable and color, decade, age, stock, or 2 methodological factors (test duration, single vs. group testing) as X-variables. Models were evaluated by assessing information criteria, residuals/random effect normality, significance of X-variables and model evaluation statistics (mean square prediction error, concordance correlation coefficient). TI duration was best explained by a color-by-decade interaction (P=0.0006). Whites in the 1980s had longer TI durations (709.43 ± 143.88 s) than browns in the 1980s (282.90 ± 59.70 s), as well as in comparison to browns (208.80 ± 50.82 s) or whites (204.85 ± 49.60 s) in the 2020s. The NO approach rate was best explained by color (P ≤ 0.05 in 3 models), age (P < 0.05 in 3 models), and decade (P=0.04). Whites had a higher approach rate (0.7 ± 0.07) than browns (0.5 ± 0.11), birds in lay a higher rate (0.8 ± 0.07) than birds prelay (0.4 ± 0.12), and approach rate for papers published in the 2000s (0.8 ± 0.09) was higher than in the 2020s (0.2 ± 0.12). The phylogenetic difference in the 1980s was no longer detectable after enforcing an upper limit on TI durations (10 min), as became common practice in later studies. Our findings suggest that phylogenetic differences in fearfulness and changes over time are test dependent, and this raises important questions and potential consequences for assessing hen welfare in commercial egg production.

Tonic immobility (freezing) during sexual and physical assaults produces stronger memory effects than other characteristics of the assaults

ABSTRACT Tonic immobility (TI) is a phylogenetically conserved, passive, obligatory defense mechanism commonly engaged during sexual and physical assaults. During TI, people become immobile while remaining conscious and later reexperience intrusive memories of both their assault and of its accompanying immobility. Here we show that this well-studied biological process has powerful effects on memory and other processes. Participants had experienced either a serious sexual (n = 234) or physical (n = 137) assault. For both the assault and its accompanying immobility, the standard measure of the peritraumatic severity of TI correlated between .40 and .65 with post-assault effects on memory, including memory of the assault and memory of the immobility, the two memory-based self-concept measures of self-blame and event centrality, and post-assault anxiety and depression. The correlations with TI were much higher than other peritraumatic characteristics commonly used to predict and describe posttraumatic effects in assaults and other traumas. The results suggest that TI should be considered for a broader, more biologically based and ecologically valid understanding of the effects of trauma on memory and memory-based reactions.

Impact of herbal medicines use on the welfare of laying Japanese quails

The objective of this study was to evaluate the effect of chamomile, lemon balm, and valerian on stress modulation, evaluating the behavior and tonic immobility of laying Japanese quail. The experimental design was completely randomized with four diets and six replications containing four laying quails (Coturnix japonica) per experimental unit, totaling 96 birds. The herbal medicines studied were control treatment; 500 mg of chamomile (Matricaria recutita L.); 500 mg of lemon balm (Melissa officinalis L.); 500 mg of valerian per kg feed (Valeriana officinalis L.). There was no significant difference (p &lt; 0.05) on the frequency of bird behaviors. However, tonic immobility showed a difference (p &gt; 0.05) between treatments. The use of chamomile, lemon balm, and valerian herbs (500 mg/kg feed) did not influence the behavior of laying Japanese quails, however, they were able to decrease the tonic immobility time of the birds, with chamomile being the herb that exercised greater effect.