Induction Of Tonic Immobility Research Articles

Effect of tonic immobility induction on selected physiological parameters in Oryctolagus cuniculus f. Domesticus rabbits

Tonic immobility (TI) is a phenomenon known as thanatosis or apparent death. The phenomenon can be induced in many ways. It occurs, for example, in the presence of a hazard, as a result of coercion through an unnatural body position or as a result of administration of certain medicines. TI is sometimes used in veterinary practice to tame patients. The aim of the study was to determine the effect of tonic immobility induction on selected physiological parameters in Oryctolagus cuniculus f. Domesticus rabbits. The study included 20 healthy rabbits, patients of a veterinary clinic, divided into two groups of 10 individuals. In the study group, TI was induced to conduct a standard clinical trial, while the control group were subjected to a standard clinical trial without TI. Heart rate, respiratory rate, pupil diameter and blood glucose concentration were measured in all animals. The measurements were performed three times: after the patient’s arrival at the clinic, after a detailed clinical examination in a normal or tonic immobility position and 15 minutes after the end of the examination. Additionally, the blood cortisol concentration was measured twice: on arrival at the clinic and at the end of the clinical trial. The results of the experiment show that miniature rabbits feel less stress during tonic immobility testing than rabbits in the standing position, and therefore this phenomenon should be used for taming animals.

The development of fault bars in domestic chickens (Gallus gallus domesticus) increases with acute stressors and individual propensity: implications for animal welfare

AbstractNegative experiences during feather growth can result in fault bar formation. Fault bars are malformations perpendicular to the rachis of the feather caused by stressful experiences during feather growth. However, there are little data on the causal effect of psychological stress on the formation of fault bars in chickens. The objective of this study was to examine the effect of acute stress in domestic chickens (Gallus gallus domesticus) on fault bar formation to validate this measure as a welfare indicator. Thirty broiler breeder pullets were housed in six cages at 21 days of age. Three cages were exposed to an acute stress protocol while the other three were the unstressed control. Feathers were marked as close as possible to the growing follicle at 21 (wing feathers) and 60 (all feathers) days of age. Acute stress came in the form of three procedures (unpredictable feed delivery, induction of tonic immobility, and crowding) repeated twice, 3-8 days apart and randomly, from 28 to 60 days of age. Wing, tail, and cover feathers were removed and measured at 60 days of age for weight, length, and number of fault bars. Exposure to acute, unpredictable stress increased the number of fault bars in wing feathers of chicks with a high number of initial fault bars. Feather growth decreased for the stressed group compared to the control. These results suggest that feather traits, including fault bars and feather growth, can be used as indicators of negative welfare in chickens.

Tonic immobility in the zebra shark Stegostoma fasciatum and its use for capture methodology

When conducting biological investigations on shark species, capture and brief restraint procedures may be required in order to collect ecological, behavioral and physiological data. Tonic immobility is an innate, reversible, coma-like stasis displayed by a large number of taxa, including sharks, and has been used for brief restraint, but is rarely used during capture itself. Here, we present a novel, non-lethal capture method of zebra sharks, Stegostoma fasciatum, using tonic immobility, in the field. Zebra sharks were caught by free diving, and on SCUBA, inducing a state of tonic immobility by quickly applying tight-fisted manual pressure to the caudal fin, instead of the dorso-ventral inversion method. Divers were then able to collect tissue samples for genetic analysis, and in some cases, maintain the animals in a state of tonic immobility during transport up to the research vessel for additional data collection. Decreased duration of anthropogenic intervention, and minimal physical struggle associated with this capture and restraint method is expected to reduce physiological markers of distress. Tonic immobility induction and other methods of non-lethal capture deserve continued investigation.

Fear and stress measurements in pure and hybrid red-legged partridges

The purposes of this study were to examine the duration of induced tonic immobility (a reliable fear indicator considered a passive anti-predator behavioural trait) and two stress indicators (heterophil to lymphocyte ratio, and fluctuating asymmetry of leg length, middle-toe length, and wing length) in females and males of the red-legged partridge, and to analyze the differences between pure and hybrid populations. A total of 132 birds (66 pure and 66 hybrid partridges; 48 females and 84 males) at 52 weeks of age were used. There was a significant difference between pure and hybrid birds in tonic immobility duration (P<0.005) and heterophil to lymphocyte ratio (P<0.02), the duration being longer and the ratio being higher in the pure group of birds. There was a significant difference between pure and hybrid birds in the relative fluctuating asymmetry of middle toe length (P<0.002) and the combined fluctuating asymmetry value of the three traits (P<0.03). There were no significant differences between sexes in any indicator of fear or stress. Thus, pure red-legged partridges were more fearful, stressed, and asymmetrical than hybrid partridges, having increased tonic immobility duration, heterophil to lymphocyte ratio, and relative fluctuating asymmetry. Results indicate that levels of fear and stress, e.g. tonic immobility duration, heterophil to lymphocyte ratio, and fluctuating asymmetry, are higher in the pure partridge, and that fear and stress indicators have been modified in hybrid partridges leading to more passive animals.

Effects of barrier perches and density on broiler leg health, fear, and performance

Deterioration of footpad and hock condition and increased stress are important welfare concerns in high-density broiler production. It has been argued that environmental enrichment may help address these issues. We hypothesized that increasing environmental complexity by providing access to barrier perches across a range of densities should improve footpad and hock health, reduce leg fluctuating asymmetry (FA), and mitigate fear in broilers without compromising bird performance. In this study, 2,088 one-day-old broiler chicks were randomly assigned to one of the following barrier and density treatment combinations over 4 replications: simple barrier, complex barrier, or no barrier (control) and low (8 birds/m(2)), moderate (13 birds/m(2)), or high (18 birds/m(2)) density. In wk 7, data were collected on average tibia width and length, FA of tibia width and tibia length, footpad and hock lesions, tonic immobility, feed conversion, final BW, and mortalities. Broilers at higher densities had more severe footpad (P < 0.0001) and hock lesions (P < 0.0001). Their tibias were also longer (P < 0.0001) and less symmetric in length (P < 0.05). The tibias of birds in complex barrier pens were more symmetric in length compared with controls (P < 0.05). Barrier treatment had no effect on hock lesions, although there was a trend for simple barriers to reduce the severity of footpad lesions compared with the control treatment (P = 0.089). Birds kept in simple barrier pens were more susceptible to tonic immobility induction (P < 0.05). Final BW, feed conversion, and mortalities were neither affected by stocking density nor by barrier inclusion. In conclusion, this study shows a negative effect of high density on broiler footpad health and FA. Although barrier perches did not appear to reduce fearfulness, the improvement in footpad health suggests that simple barriers may provide key welfare benefits to broiler chickens.

Influence of Intermittent Lighting on Broiler Performance, Incidence of Tibial Dyschondroplasia, Tonic Immobility, Some Blood Parameters and Antibody Production

The aim of this study was to determine the effect of two lighting programs (continuous lighting (CL) 24L:0D and intermittent lighting (IL) 1L:3D) on the broiler performance, carcass traits, incidence of tibial dyschondroplasia (TD), relative asymmetry (RA), duration of induced tonic immobility (TI), heterophils-lymphocytes ratio (H/L), serum glucose, cholesterol and triglyceride levels. The chicks were randomly divided into 2 treatment groups consisting of 100 chicks per treatment, continuous lighting (CL) 24L:0D or intermittent lighting (IL) 1L:3D. Each treatment consists of 5 replicates of 20 chicks. The experimental period was 6 weeks. Use of IL decreased feed to gain ratio, improved immune response and reduced fearful. Body weight, carcass traits, TD and stress parameters (organ weights, RA, H/L, glucose, cholesterol and triglyceride levels) were not significant in different lighting groups. As a result IL was beneficial for producers and chickens than CL.

Adrenocortical responses of Japanese quail to a routine weighing procedure and to tonic immobility induction

Tonic immobility (TI) is induced by brief manual restraint, and it is a commonly used test of fearfulness, particularly in poultry. However, in view of increasing ethical concerns about experimentation on living animals, there is a need to ensure that the tests used do not elicit unacceptable distress. In the United Kingdom, there is some debate as to whether TI should be classified as a regulated experimental procedure that requires a Home Office license to experiment on living animals under the Animals (Scientific Procedures) Act of 1986. The present study compared plasma corticosterone (PC) concentrations in undisturbed Japanese quail (controls) with those exposed to the induction of TI or those exposed to a routine weighing procedure. Circulating PC concentrations were higher following TI induction or weighing than in the controls, but the 2 treatments elicited similar adrenocortical responses. Further, the PC levels found here were lower than those reported elsewhere when quail were exposed to crating, transport, or mechanical immobilization stressors. We therefore concluded that the induction of TI might be best regarded as a mild stressor. Furthermore, studies using this technique can identify ways of alleviating fear and thereby improving well-being. Collectively, we believe that the use of TI is justified, and it does not require classification as a regulated procedure in the United Kingdom or elsewhere.

Effects of Cage Density on Fear-Related Behavioral Response and Activity of Layers

Two experiments were conducted to study the effects of cage density on fear-related behavioral response and activity of White Leghorn layers. In Experiment 1, 20-wk old pullets were placed into 30.5 × 50.8 cm cages at the rate of one, two, three, and four birds per cage for Treatments 1, 2, 3, and 4, respectively. In Experiment 2, birds were placed into cages (30.5 × 50.8 cm) at the rate of one, two, three, four, three, two, and three birds per cage for Treatments 1, 2, 3, 4, 5, 6, and 7, respectively, at 20 wk of age. At 28 wk of age, one bird was removed from each cage in Treatment 5, and one bird was added to each cage in Treatments 6 and 7. Fear-related behavioral response of the birds, as determined by the duration of induced tonic immobility (TI), and bird activity, as determined by the head movement (HM) count, were measured at 52 wk of age in Experiment 1, and at 29, 36, and 52 wk of age in Experiment 2.Increasing cage density had no effect on fear-related response of the birds in both experiments. Cage density effect on bird activity was not consistent. In Experiment 1, HM count was not affected by cage density, whereas in Experiment 2, pullets in the multiple-bird cage had a lower (P ≤ .05) HM count (three-period average) than the birds housed individually. There was no correlation between the duration of induced TI and HM count in both experiments. This study revealed that cage density and the addition or removal of a cage mate to or from a multiple-bird cage did not affect fear-related response of the birds and had no consistent effect on bird activity, and that the level of activity had no relationship with fear-related response.

Realized Heritability of Tonic Immobility in White Leghorn Hens: A Replicated Single Generation Test

Fearfulness was measured as latency to recover from induced tonic immobility using White Leghorn hens from a population originated by crossing three different strains selected for egg number and egg weight. Realized heritability was calculated in a single generation selection experiment with eight replicates, each consisting of 76 40-wk-old females from which 21% were selected for decreased tonic immobility duration. A randomly selected control population was maintained for each replicate. Separately from this experiment, fear differences between ages and sexes were investigated at 1, 2, 4, 8, 12, 16, 20, 24, 28, and 32 wk. The realized heritability (.32 ± .10) indicates that induced tonic immobility should respond to selection. It was numerically higher than the estimate calculated by half-sib analysis of variance in the base population (.18 ± .07); the logarithmic transformation did not yield higher heritability estimates. Crossing effects were evaluated in two different crossbreds, i.e., Leghorn × Castellana and Buff Prat × White Prat, which suggested important negative heterotic effects for this fear-related trait (−31% and −54%, respectively). Significant (P < .05) quadratic and cubic variation between 1 and 32 wk of age was obtained in females and males, respectively; the involvement of these age effects make it difficult to generalize about realized heritability for tonic immobility. Tonic immobility increased from 32 to 72 wk. Differences between the sexes were apparent, males showing longer tonic immobility durations than females except in the postjuvenile period before sexual maturity, suggesting a relationship between this trait and hormonal changes.

Heritabilities for Behavioral and Production Traits in Japanese Quail (Coturnix coturnix japonica) Bidirectionally Selected for Dustbathing Activity

Heritability estimates from sire, dam, and sire plus dam components of variance were obtained for behavioral and production traits in Japanese quail selected for low or high dustbathing activity for 17 generations and the randombred control. Behavioral observations in males included aspects of dustbathing behavior (short-term and long-term recording), mating behavior, locomotor activity, fear-related responses (reaction towards a pencil, emergence from a box, and recovery from induced tonic immobility), and aggressive reactions towards a quail-head model. Numbers of offspring involved across lines and generations ranged from 606 to 8,171. Estimates for the production traits 12-wk body weight, plumage condition, age at first egg, and laying intensity from 12 to 23 wk were based on 8,171 males and 4,801 females.Heritabilities for behavioral traits were of low to moderate magnitude. Estimates were high for 12-wk body weight, and moderate to low for the other production characteristics. Comparisons between heritabilities for behavioral and production traits are to be viewed with caution. Low estimates for behavioral traits might result from high phenotypic variances due to problems in definition and measurement of the patterns. Assumptions on the relationship between behavioral patterns and fitness should not only rely upon heritability estimates but also should be examined in crossing experiments.

Beak Trimming Effects on Behavior Patterns, Fearfulness, Feathering, and Mortality Among Three Stocks of White Leghorn Pullets in Cages or Floor Pens ,

White Leghorn pullets of the Y1, Y2, and North Central Randombred (NCR) experimental stocks were used. Half of the birds of each stock had half of the upper and less of the lower mandible removed at 4 wk of age by making a V-shaped cut as viewed from the side (BT), whereas the other half retained their beaks intact (IN). Pullets were moved from growing pens to a layer house at 18 wk of age. Seventy-two cages and 30 floor pens were filled with 6 and 20 birds per unit, respectively. Pullets within a cage or floor pen were all of the same genetic stock and beak treatment. All measurements were performed within 10 wk after housing, except for mortality in cages.When kept in cages, genetic stocks did not show behavioral differences. However, in floor pens, stock differences were detected in feeding, crouching, and nonaggressive pecking. When kept in cages, the stocks also differed in 24-wk body weight, weight gain from 18 to 24 wk, and certain measures of fearfulness in both cages and pens, and in feather condition at 21 and 22 wk. Mortality from cannibalism and hen-days survival of caged IN pullets differed among genetic stocks. Mortality from cannibalism was absent among pullets kept in experimental floor pens.In cages, BT pullets were less active, gained less weight, and had lower incidence of cannibalism than IN pullets. Also, BT pullets were less nervous and had better feather condition than IN pullets. However, trimming beaks to prevent cannibalism was less effective in NCR pullets than in Y1 or Y2 pullets.In floor pens, BT pullets showed less activity and reduced feeding frequency and less fearfulness as indicated by duration of induced tonic immobility. Agonistic behaviors were not different between BT and IN pullets.From these results, beak trimming could be interpreted as having either stressful or stress-alleviating effects, depending on the criteria used. However, proper beak trimming appears beneficial when cannibalistic pecking is likely to be a problem. The relative benefits of beak trimming vary among genetic stocks.

Thermal correlates of tonic immobility and social isolation in chickens

Previous research has shown that core temperature in chickens drops following the induction of tonic immobility (TI), while hyperthermic trends emerge shortly after response termination. Other research has shown that birds placed in social isolation also become hyperthermic. Since testing for TI is usually carried out while animals are isolated, there is a question as to whether the hyperthermic reaction after the termination of TI has any relation to the episode of TI itself as opposed to being due to the effects of social isolation per se. The present series of studies found that although social isolation did produce significantly longer durations of TI and that the core temperature of isolated birds was affected, when core temperatures were independently raised or lowered, no significant differences were found in TI durations relative to controls. Additionally, in contrast to core temperature changes, shank temperature showed the opposite effect, while another peripheral temperature measure, wing temperature, remained stable.

Physiological changes during tonic immobility in Gallus gallus var domesticus

Physiological parameters were examined in the hen in response to the induction of tonic immobility (TI). The induction of TI was associated with EEG arousal, low shank temperature and elevated heart rate. However, shortly after the adoption of TI, the EEG showed a predominantly slow-wave deactivated pattern, muscle tone fell and sympathetic nervous activity was reduced, as indicated by declining heart rate and peripheral vasodilation. Core temperature remained constant at 42°C throughout the immobility response. Several instances of EEG-behavioural dissociation were observed. The results are discussed in terms of “cut-off” and waning of the induced fear state.

Laying Performance and Fear Response of White Leghorns as Influenced by Floor Space Allowance and Group Size

Three experiments were conducted with White Leghorn pullets housed in litter-floored pens to determine the effects of floor space allowance and group size on laying performance and fear response. In Experiment 1, 17 birds were housed at a floor space allowance of .40 or .29 m2/bird. In Experiment 2, 22 or 16 birds were housed at a floor space allowance of .31 m2/bird. The following treatments were used in Experiment 3: 1) 26 birds per pen at. 19 m2/bird, 2) 36 birds per pen at. 19 m2/bird, and 3) 26 birds per pen at .26 m2/bird. The test period was from 20 to 52 wk of age in each experiment. Duration of the induced tonic immobility, measured at 52 wk of age, was used as a criterion of fearfulness.Decreasing floor space allowance per bird, increasing group size per pen or a combination of the two had no significant effect on final body weight, hen-day egg production, feed efficiency, egg weight, albumen height, or fearfulness of the bird. Decreasing floor space per bird while holding the number of birds per pen constant significantly (P<.05) increased mortality. Birds given less floor space consumed significantly (P<.05) more feed than birds given more floor space in Experiment 1. This study indicates that the birds' hen-day egg production, feed efficiency, and fearfulness are not significantly (P>.05) influenced by floor space allowance or group size and that effects of floor space allowance and those of group size are not additive.

Fearful and Associated Responses of Caged White Leghorn Hens: Genetic Parameter Estimates ,

Data were obtained from hens kept in three-bird cages in two, full-year experiments. Feather damage and loss scores, several fear-indicating variables, and measures of egg production were analyzed to obtain estimates of heritabilities and genetic and phenotypic correlations. Heritability estimates were slightly biased because data on individual hens were not available for most traits. Heritability estimates of productivity traits were fairly consistent with values obtained by others, except for age at sexual maturity, which was exceptionally low. Estimated heritability of egg number, based on a 15-day palpation period following full-year egg production, was also low. Feather score appeared to be moderately heritable. Heritability estimates involving escape and avoidance behavior and duration of induced tonic immobility indicate that those fear-related traits should respond to selection, if measured appropriately. None of the correlation coefficient estimates involving associations among feather scores, fear-inducing variables, and measures of egg production differed significantly from zero.

Research Note: Effects of Floor Space Allowance and Group Size on Fear Response of White Leghorns

Three experiments were conducted in litter-floor pens to study fear response of White Leghorn layers as affected by floor space allowance and group size. In Experiment 1, 37 birds were housed at a floor space allowance of. 18 or. 13 m2/bird. In Experiment 2, 50 or 36 birds were housed at a constant floor space allowance of. 14 m2/bird. The following treatments were used in Experiment 3:51 or 37 birds per pen at.13 m2/bird; and 37 birds per pen at .19 m2/bird. The study period was from 20 to 52 wk of age in each experiment. Duration of the induced tonic immobility, measured at 52 wk of age, was used as a criterion of fearfulness.Decreasing floor space allowance per bird or increasing group size per pen had no significant effect on fearfulness. Also, the effects of floor space allowance and group size on fear response were not additive under the conditions of this study.

Studies of the Relationship Between Fear-Related Responses and Production Traits in Japanese Quail (Cotumix coturnix japonica) Bidirectionally Selected for Dustbathing Activity

In three experiments, female Japanese quail originating from lines selected for low or high dustbathing activity and the randombred control were studied. Fearfulness was measured as latencies to emerge from a box and to recover from induced tonic immobility (TI), and the influence of social disturbance by repeated placement in male cages during the breeding season, and the effect of repeated frightening by exposure to unfamiliar objects on egg quality traits was examined. Eggs (a total of 790) were collected over a 5-day period, weighed, and examined; body weight at 12 wk was recorded for all birds.Low line females had longer latencies to emerge than high line birds. It is suggested that selection for dustbathing activity had resulted in correlated changes in the susceptibility to fear. These genetic differences in fearfulness, however, may be only detectable at lower levels of induced fear.The social disturbance and frightening treatments did not affect egg production or the incidence of shell-less eggs. Repeated disturbances caused a significantly lower degree of egg shell calcium coating on the posttreatment day, suggesting that eggs were laid prematurely. As only 12.8% of all eggs examined were classified as uncoated, it is concluded that coatings are part of the normal egg shell pigmentation in the quail lines studied. There was no apparent correlation between emergence test and TI. The association between fear-related responses and production traits was of low magnitude.

Fear-Related Behavior of Hens in Cages: Effects of Rearing Environment, Age, and Habituation

At 18 weeks, pullets reared in floor pens and cages were placed in cages designed for laying hens. Tests were conducted for escape and avoidance behavior and for duration of tonic immobility at 23 and 40 weeks of age. Rearing environment effects were not detected for either measure. Paired comparisons did not reveal effects of age or habituation on duration of induced tonic immobility.

Effects of simulated predator eye illumination on tonic-immobility duration in Coturnix quail

Gallup, Nash and Ellison (1971) reported that the presence of artificial eyes increased both susceptibility to induction of tonic immobility (TI) and duration of the immobility reaction in domestic chicks. Further, they reported differential effects for both susceptibility and duration for color and type of eye stimulus. One interpretation of the differential effects suggests that the eye stimuli individually differed with respect to incidental light reflectance. The present study investigated the relationship between artificial eye illumination and duration of restraint-induced TI in habituated Japanese quail (Coturnix japonica). Results suggest that the differences reported by Gallup et al. may be due to the relative brightness of the eye stimuli.

Tonic Immobility as a Response to Rape in Humans a Theoretical Note

Recently (1977) a special issue of The Psychological Record was devoted to the topic of tonic immobility (also known as “animal hypnosis”). The present paper extends that coverage by examining the applicability of the designation tonic immobility to special states of behavioral inhibition in humans, particularly the occurrence of rape-induced paralysis commonly reported by rape victims. Since fear, overtones of predation, contact, and restraint are common denominators to rape and the induction of tonic immobility, and because the reactions by rape victims are often isomorphic with behaviors shown by immobilized animals, it is concluded that tonic immobility and rape-induced paralysis represent the same phenomenon. The adaptive value of this reaction to rape is briefly discussed.