Siobhan M. Abeyesinghe

Can domestic fowl, Gallus gallus domesticus, show self-control?

An important aspect of cognition is whether animals live exclusively in the present or can anticipate the future. Defined as self-control, the ability to choose a large, remote reinforcer over a small, proximate reinforcer available at the same frequency has been examined in a number of species, often proving difficult to demonstrate. We investigated self-control for food in domestic fowl using a standard two-key operant task and an equivalent two-choice return maze (TCRM) task. When hens chose between a 2-s delay to a 3-s feed access (impulsive) and a 6-s delay to a 7-s feed access (self-control), they appeared unable to discriminate in the TCRM but were impulsive in the operant task. We explored reasons for not choosing self-control in the operant task, first by examining the relation between feed access time and actual feed intake. A second operant experiment examined whether failure to show self-control could be attributed to an inability to combine the delay and access (quantity) reward information associated with choices to reach overall predictions of value. New hens chose between a 2-s delay to a 3-s feed access (impulsive) and either a 22-s delay to a 22-s feed access (standard self-control) or a 6-s delay to a 22-s feed access (jackpot self-control). While hens were impulsive in the standard condition, they showed significant and pronounced self-control in the jackpot condition, eliminating the possibility of an absolute cognitive constraint. Impulsive behaviour can instead be explained by temporal discounting: perceived depreciation of reward value as a function of the uncertainty associated with delay. Implications for welfare are discussed.

Estimation of the number and demographics of companion dogs in the UK

BackgroundCurrent estimates of the UK dog population vary, contain potential sources of bias and are based on expensive, large scale, public surveys. Here, we evaluate the potential of a variety of sources for estimation and monitoring of the companion dog population in the UK and associated demographic information. The sources considered were: a public survey; veterinary practices; pet insurance companies; micro-chip records; Kennel Club registrations; and the Pet Travel Scheme. The public survey and subpopulation estimates from veterinary practices, pet insurance companies and Kennel Club registrations, were combined to generate distinct estimates of the UK owned dog population using a Bayesian approach.ResultsWe estimated there are 9.4 (95% CI: 8.1-11.5) million companion dogs in the UK according to the public survey alone, which is similar to other recent estimates. The population was judged to be over-estimated by combining the public and veterinary surveys (16.4, 95% CI: 12.5-21.5 million) and under-estimated by combining the public survey and insured dog numbers (4.8, 95% CI: 3.6-6.9 million). An estimate based on combining the public survey and Kennel Club registered dogs was 7.1 (95% CI: 4.5-12.9) million. Based on Bayesian estimations, 77 (95% CI: 62-92)% of the UK dog population were registered at a veterinary practice; 42 (95% CI: 29-55)% of dogs were insured; and 29 (95% CI: 17-43)% of dogs were Kennel Club registered. Breed demographics suggested the Labrador was consistently the most popular breed registered in micro-chip records, with the Kennel Club and with J. Sainsburys PLC pet insurance. A comparison of the demographics between these sources suggested that popular working breeds were under-represented and certain toy, utility and miniature breeds were over- represented in the Kennel Club registrations. Density maps were produced from micro-chip records based on the geographical distribution of dogs.ConclusionsA list containing the breed of each insured dog was provided by J. Sainsburys PLC pet insurance without any accompanying information about the dog or owner.

Controlled atmosphere stunning of broiler chickens. I. Effects on behaviour, physiology and meat quality in a pilot scale system at a processing plant

1. The effects of controlled atmosphere stunning on the behaviour, physiology and carcase and meat quality of broiler chickens were studied experimentally in a pilot scale plant. 2. Gas mixtures tested were: single phase anoxic mixture (90% Ar in air, <2% O2); single phase hypercapnic anoxic mixture (60% Ar, 30% CO2 in air, <2% O2); and biphasic hypercapnic hyperoxygenation mixture (anaesthetic phase, 40% CO2, 30% O2, 30% N2; euthanasia phase, 80% CO2, 5% O2, 15% N2). 3. Anoxic stunning resulted in the least respiratory disruption, mandibulation and motionlessness, but most head shaking, leg paddling and twitching. Loss of posture occurred soonest with hypercapnic anoxia with the earliest and most twitching and wing flapping in individuals and earliest leg paddling. Biphasic birds were most alert, exhibited most respiratory disruption and mandibulation, and had the latest loss of posture and fewest, but longest bouts of wing flapping and least leg paddling and twitching. 4. Significant and sudden bradycardia and arrhythmia were evident with all gas mixtures and were not related solely to anoxia or hypercapnia. Birds stunned by Ar anoxia showed a slightly more gradual decline from baseline rates, compared with hypercapnic mixtures. 5. Few differences were found between gas mixes in terms of carcase and meat quality. Initial bleeding rate was slowest in biphasic-stunned birds, but total blood loss was not affected. Acceleration of post-mortem metabolism in anoxic-stunned birds was not sufficient to allow de-boning within 5 h without the risk of tough meat. 6. On welfare grounds and taking into account other laboratory and field studies, a biphasic method (using consecutive phases of anaesthesia and euthanasia) of controlled atmosphere stunning of broilers is potentially more humane than anoxic or hypercapnic anoxic methods using argon or nitrogen.

Controlled atmosphere stunning of broiler chickens. II. Effects on behaviour, physiology and meat quality in a commercial processing plant

1. The effects of controlled atmosphere stunning on behavioural and physiological responses, and carcase and meat quality of broiler chickens were studied experimentally in a full scale processing plant. 2. The gas mixtures tested were a single phase hypercapnic anoxic mixture of 60% Ar and 30% CO2 in air with <2% O2, and a biphasic hypercapnic hyperoxygenation mixture, comprising an anaesthetic phase, 40% CO2, 30% O2, 30% N2, followed by an euthanasia phase, 80% CO2, 5% O2, 15% N2. 3. Birds stunned with Ar + CO2 were more often observed to flap their wings earlier, jump, paddle their legs, twitch and lie dorsally (rather than ventrally) than those stunned with CO2 + O2. These behaviours indicate a more agitated response with more severe convulsions during hypercapnic anoxia, thereby introducing greater potential for injury. 4. Heart rate during the first 100 s of gas stunning was similar for both gases, after which it remained constant at ≈230 beats/min for CO2 + O2 birds whereas it declined gently for Ar + CO2 birds. 5. In terms of carcase and meat quality, there appeared to be clear advantages to the processor in using CO2 + O2 rather than Ar + CO2 to stun broiler chickens, for example, a much smaller number of fractured wings (1·6 vs. 6·8%) with fewer haemorrhages of the fillet. 6. This study supports the conclusions of both laboratory and pilot scale experiments that controlled atmosphere stunning of broiler chickens based upon a biphasic hypercapnic hyperoxygenation approach has advantages, in terms of welfare and carcase and meat quality, over a single phase hypercapnic anoxic approach employing 60% Ar and 30% CO2 in air with <2% O2.

Measuring and modelling the spatial contrast sensitivity of the chicken (Gallus g. domesticus)

The spatial contrast sensitivity (CSF) of the chicken has been measured using a behavioural technique. The results obtained show that spatial vision in this species is relatively poor compared with the human observer. For a visual stimulus luminance of 16 c dm(-2), the upper frequency limit of spatial vision in the chicken (acuity) was found to be about 7.0 c deg(-1), with peak spatial vision occurring at around 1.0 c deg(-1). Under equivalent stimulus conditions, the acuity of the human is around 50 c deg(-1) with a peak in spatial vision at about 3.0 c deg(-1). Peak spatial contrast sensitivity in the chicken was also found to be only about 2% that for the human. At a lower stimulus luminance of 0.1 c dm(-2), the chicken CSF reduced in overall magnitude and indicated an acuity level of about 5.0 c deg(-1). These experimental results were successfully modelled using modulation transfer (MTF) theory. This theoretical treatment enabled important neural mechanisms underlying spatial vision in the chicken to be revealed. The role played by spatial vision in the chickens ability to recognise detailed shapes in its visual environment was also examined by deploying the CSF as a visual weighting function with the Fourier series of a chicken comb.

Prioritisation of companion dog welfare issues using expert consensus

Resources for tackling animal welfare issues are often limited. Obtaining a consensus of expert opinion on the most pressing issues to address is a valuable approach to try to ensure that resources are wisely spent. In this study, seven independent experts in a range of disciplines (including veterinary medicine, animal behaviour and welfare science and ethics) were consulted on the relative prioritisation of welfare issues impacting companion dogs in Great Britain. Experts first anonymously ranked the priority of 37 welfare issues, pre-defined from a literature review and an earlier published survey. In a subsequent two-day panel workshop, experts refined these issues into 25 composite groups and used specific criteria to agree their relative priorities as a Welfare Problem (WP; incorporating numbers of dogs affected, severity, duration and counter-balancing benefits) and a Strategic Priority (SP; a combination of WP and tractability). Other criteria — anthropogenicity, ethical significance and confidence in the issue-relevant evidence — were also discussed by the panel. Issues that scored highly for both WP and SP were: inappropriate husbandry, lack of owner knowledge, undesirable behaviours, inherited disease, inappropriate socialisation and habituation and conformation-related disorders. Other welfare issues, such as obese and overweight dogs, were judged as being important for welfare (WP) but not strategic priorities (SP), due to the expert-perceived difficulties in their management and resolution. This information can inform decisions on where future resources can most cost-effectively be targeted, to bring about the greatest improvement in companion dog welfare in Great Britain.

Stimulus luminance and the spatial acuity of domestic fowl (Gallus g. domesticus)

The luminance dependence of spatial acuity in domestic fowl was measured directly over stimulus luminances ranging from 0.06 to 57.35 cd m(-2). At the highest luminance, acuity was around 6.5 c deg(-1), in agreement with previous studies in this species. As stimulus luminance decreased, acuity fell with increasing rate to 3.2 c deg(-1) at 0.06 cd m(-2), following the same shape as acuity functions for other mammalian and avian species. These findings suggest that the rod-cone transition for domestic fowl is between 0.45 and 1.79 cd m(-2). Over the photopic range from 1.79 to 57.35 cd m(-2) the change of acuity for fowl was 1%, compared with 32% for humans. For domestic fowl, the Rovamo-Barten MTF model of contrast sensitivity accounted for the behaviour of acuity as a function of luminance down to mesopic levels.

Investigating social discrimination of group members by laying hens.

Social relationships in domestic fowl are commonly assumed to rely on social recognition and its pre-requisite, discrimination of group-mates. If this is true, then the unnatural physical and social environments in which commercial laying hens are typically housed, when compared with those in which their progenitor species evolved, may compromise social function with consequent implications for welfare. Our aims were to determine whether adult hens can discriminate between unique pairs of familiar conspecifics, and to establish the most appropriate method for assessing this social discrimination. We investigated group-mate discrimination using two learning tasks in which there was bi-directional exchange of visual, auditory and olfactory information. Learning occurred in a Y-maze task (p<0.003; n=7/8) but not in an operant key-pecking task (p=0.001; n=1/10). A further experiment with the operant-trained hens examined whether failure was specific to the group-mate social discrimination or to the response task. Learning also failed to occur in this familiar/unfamiliar social discrimination task (p=0.001; n=1/10). Our findings demonstrate unequivocally that adult laying hens kept in small groups, under environmental conditions more consistent with those in which sensory capacities evolved, can discriminate group members: however, appropriate methods to demonstrate discrimination are crucial.

The behavioural and physiological responses of farmed red deer (Cervus elaphus) penned adjacent to other species

Abstract The experiment describes the implications of red deer ( Cervus elaphus ) being kept in pens in close proximity to other species as may occur during abattoir lairage. Twenty groups of five male yearling red deer were used to study behavioural and physiological responses over a 2-h period to one of five treatments: red deer penned adjacent to either an empty pen, unfamiliar red deer, cattle or pigs, and red deer which had previously been exposed to cattle (previously grazed adjacent to cattle) penned adjacent to cattle. Alert behaviour was significantly affected by treatment and groups of red deer penned next to cattle spent more time being alert than when next to unfamiliar red deer (0.68 vs. 0.32 scans; P P P P P −1 ) than in the other treatments (mean values between 33.0 and 53.1 nmol l −1 ; P P −1 ) but there was no treatment effect on LDH5 isoenzyme activity. It was concluded that there was some evidence to suggest that previous exposure to cattle made red deer exhibit more aversion to cattle when subsequently penned adjacent to them and that pigs appeared to be more aversive to the red deer than cattle.

The impact of chronic environmental stressors on growing pigs, Sus scrofa (Part 2): social behaviour

The effects of common and concurrent environmental stressors on the social behaviour of farm animals are poorly understood. Here, we report the results of a multifactorial experiment designed specifically to examine the individual, additive or interactive effects of elevated ammonia, noise and low light (LL) levels on the social behaviour of growing pigs. Social behaviour was measured in terms of the nature, frequency and duration of both initiated and response behaviours for 4 weeks following mixing of the groups. General activity patterns, group cohesion and social discrimination were also examined as a function of the environmental treatments. Elevated concentrations of atmospheric ammonia (∼20 v. <5 ppm) and LL intensity (∼40 v. 200 lux) had the most pronounced effects, particularly on the nature of social interactions, with pigs under these conditions showing more aggression in the early stages of the experiment. In addition, pigs exposed to a high level of mechanical noise representative of artificial ventilation (∼80 v. 40 dB [A]) were less submissive to aggressive acts, while pigs in ∼20 ppm ammonia showed more reciprocated aggression when in coincident LL (<40 lux). The results indicate that atmospheric ammonia at commonly experienced concentrations may undermine social stability, particularly in the presence of low lighting, though the mechanisms are currently unknown. These findings have implications for the welfare of growing pigs and hence policy makers and farmers alike, with respect to the improvement of welfare in intensive pig farming.