Richard M A Parker

Sensitivity to reward loss as an indicator of animal emotion and welfare

The scientific study of animal emotion is an important emerging discipline in subjects ranging from neuroscience to animal welfare research. In the absence of direct measures of conscious emotion, indirect behavioural and physiological measures are used. However, these may have significant limitations (e.g. indicating emotional arousal but not valence (positivity versus negativity)). A new approach, taking its impetus from human studies, proposes that biases in information processing, and underlying mechanisms relating to the evaluation of reward gains and losses, may reliably reflect emotional valence in animals. In general, people are more sensitive to reward losses than gains, but people in a negative affective state (e.g. depression) are particularly sensitive to losses. This may underlie broader findings such as an enhanced attention to, and memory of, negative events in depressed individuals. Here we show that rats in unenriched housing, who typically exhibit indicators of poorer welfare and a more negative affective state than those in enriched housing, display a prolonged response to a decrease in anticipated food reward, indicating enhanced sensitivity to reward loss. Sensitivity to reward reduction may thus be a valuable new indicator of animal emotion and welfare.

Prevalence of risk factors for tail biting on commercial farms and intervention strategies

A husbandry advisory tool (HAT) was devised to help pig producers and their advisors identify and minimise possible risk factors for tail biting in finishing pigs. The prevalence of 83 risk factors identified from the literature and expert opinion was recorded on 65 commercial pig farms in England between May 2007 and July 2009. Those considered most important were associated with atmosphere/environment, environmental enrichment, the provision of food/drink and animal health factors. Forty-six farms received advice on minimising these risks and, of these, 27 also received a financial incentive to encourage the uptake of advice. A reduction in risk factors was observed on 42/57 farms visited at the end of the study, with the greatest reduction occurring on the farms that had been incentivised. However, farms not receiving advice also had reduced risk factors associated with atmosphere/environment and stocking density over the course of the study. In conclusion, while some risk factors are structural and require substantial capital investment to change, a significant reduction in the risk of tail biting can be achieved on many farms through the systematic evaluation and modification of management practices.

Housing conditions affect rat responses to two types of ambiguity in a reward–reward discrimination cognitive bias task

Highlights • We investigated how an unpredictable housing treatment (UHT) influenced measures of rat affect.• Control rats showed more anxiety-like behaviour in open-field and elevated plus maze tests than UHT rats.• Controls also made more ‘pessimistic’ decisions in an automated cognitive bias task.• Our go/go reward–reward task was learnt faster than previous automated go/go tasks.• We developed a new ambiguity test that may probe biases in attentional processes.

The place of experimental design and statistics in the 3Rs.

The 3Rs--replacement, reduction, and refinement--can be applied to any animal experiment by researchers and other bodies seeking to conduct those studies in as humane a manner as possible. Key to the success of this endeavor is an appreciation of the principles of good experimental design and analysis; these need to be considered in concert before any data is collected. Indeed, many of the principles central to helping achieve the objectives of the 3Rs-such as conducting valid, reliable, and efficient experiments; clearly and transparently reporting findings; and ensuring that an appreciation and understanding of animal welfare plays a central role in laboratory practice-are to the betterment of research per se.

Lameness is consistently better at predicting broiler chicken performance in mobility tests than other broiler characteristics

To determine whether lame broilers are in pain it is necessary to compare measures of lameness and mobility before and after analgesic treatment. Such measures should not be unduly affected by other bird characteristics. This study assessed the performance of lame (gait score, GS 3–4) and non-lame (GS 0–1) broilers using two mobility tests: (i) a novel test to assess broiler ability to access resources when housed in groups (Group Obstacle test); and (ii) a Latency-to-Lie (LTL) test. Outcome test measures included number of obstacle crossings, latency to cross an obstacle, and time taken to sit in shallow water. Associations between outcome test measures and other bird characteristics (established lameness risk-factors), including strain, sex, age, mass, contact dermatitis and pathology, were also investigated. The performance of high-GS and low-GS broilers differed in both mobility tests and no other bird characteristics were as consistent a predictor as lameness. This demonstrates that mobility impairments are closely related to lameness assessed using GS, and that there is a component of lameness that cannot be explained by other bird characteristics (eg being male and heavy). This component may represent pain or discomfort. Both mobility tests are suitable for further application with analgesic testing to classify lameness-associated pain in broilers.

Thermal nociceptive threshold testing detects altered sensory processing in broiler chickens with spontaneous lameness

Lameness is common in commercially reared broiler chickens but relationships between lameness and pain (and thus bird welfare) have proved complex, partly because lameness is often partially confounded with factors such as bodyweight, sex and pathology. Thermal nociceptive threshold (TNT) testing explores the neural processing of noxious stimuli, and so can contribute to our understanding of pain. Using an acute model of experimentally induced articular pain, we recently demonstrated that TNT was reduced in lame broiler chickens, and was subsequently attenuated by administration of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). This study extended these findings to a large sample of commercial broilers. It examined factors affecting thermal threshold (Part 1) and the effect of an NSAID drug (meloxicam, 5 mg/kg) and of an opioid (butorphanol; 4 mg/kg) (Part 2). Spontaneously lame and matched non-lame birds (n = 167) from commercial farms were exposed to ramped thermal stimulations via a probe attached to the lateral aspect of the tarsometatarsus. Baseline skin temperature and temperature at which a behavioural avoidance response occurred (threshold) were recorded. In Part 1 bird characteristics influencing threshold were modelled; In Part 2 the effect of subcutaneous administration of meloxicam or butorphanol was investigated. Unexpectedly, after accounting for other influences, lameness increased threshold significantly (Part 1). In Part 2, meloxicam affected threshold differentially: it increased further in lame birds and decreased in non-lame birds. No effect of butorphanol was detected. Baseline skin temperature was also consistently a significant predictor of threshold. Overall, lameness significantly influenced threshold after other bird characteristics were taken into account. This, and a differential effect of meloxicam on lame birds, suggests that nociceptive processing may be altered in lame birds, though mechanisms for this require further investigation.

A Two-Year Participatory Intervention Project with Owners to Reduce Lameness and Limb Abnormalities in Working Horses in Jaipur, India

Background Participatory methods are increasingly used in international human development, but scientific evaluation of their efficacy versus a control group is rare. Working horses support families in impoverished communities. Lameness and limb abnormalities are highly prevalent in these animals and a cause for welfare concern. We aimed to stimulate and evaluate improvements in lameness and limb abnormalities in horses whose owners took part in a 2-year participatory intervention project to reduce lameness (PI) versus a control group (C) in Jaipur, India. Methodology/Principal Findings In total, 439 owners of 862 horses participated in the study. PI group owners from 21 communities were encouraged to meet regularly to discuss management and work practices influencing lameness and poor welfare and to track their own progress in improving these. Lameness examinations (41 parameters) were conducted at the start of the study (Baseline), and after 1 year and 2 years. Results were compared with control horses from a further 21 communities outside the intervention. Of the 149 horses assessed on all three occasions, PI horses showed significantly (P<0.05) greater improvement than C horses in 20 parameters, most notably overall lameness score, measures of sole pain and range of movement on limb flexion. Control horses showed slight but significantly greater improvements in four parameters, including frog quality in fore and hindlimbs. Conclusions/Significance This participatory intervention succeeded in improving lameness and some limb abnormalities in working horses, by encouraging changes in management and work practices which were feasible within owners’ socioeconomic and environmental constraints. Demonstration of the potentially sustainable improvements achieved here should encourage further development of participatory intervention approaches to benefit humans and animals in other contexts.

Effects of carprofen, meloxicam and butorphanol on broiler chickens’ performance in mobility tests

Lame broiler chickens perform poorly in standardised mobility tests and have nociceptive thresholds that differ from those of nonlame birds, even when confounding factors such as differences in bodyweight are accounted for. This study investigated whether these altered responses could be due to pain, by comparing performance in a Group Obstacle test and a Latency to Lie (LTL) test of lame (Gait Score [GS] 2.5–4) and non-lame (GS 0–1) broilers administered analgesia or a saline control. We used exploratory subcutaneous doses of the non-steroidal anti-inflammatory drugs (NSAIDs), meloxicam (5 mg kg) or carprofen (35 mg kg) or the opioid butorphanol tartrate (4 mg kg). We included butorphanol to explore the possibility that NSAIDs could improve mobility by reducing inflammation without necessarily invoking an analgesic effect. Lameness was a significant predictor in all analyses. Neither the number of obstacle crossings nor latency to cross an obstacle was significantly changed by either NSAID, but LTL was longer in lame birds given carprofen and meloxicam than in lame birds given saline. LTL was associated with foot-pad dermatitis and ameliorated by both NSAIDs. Butorphanol did not affect LTL but appeared soporific in the obstacle test, increasing latency to cross and, in non-lame birds, reducing the number of crossings. Combined with data from other studies, the results suggest carprofen and meloxicam had some analgesic effect on lame birds, lending further support to concerns that lameness compromises broiler welfare. Further investigation of opioid treatments and lameness types is needed to disentangle effects on mobility and on pain.

Intermediate Notation for Provenance and Workflow Reproducibility

We present a technique to capture retrospective provenance across a number of tools in a statistical software suite. Our goal is to facilitate portability of processes between the tools to enhance usability and to support reproducibility. We describe an intermediate notation to aid runtime capture of provenance and demonstrate conversion to an executable and editable workflow. The notation is amenable to conversion to PROV via a template expansion mechanism. We discuss the impact on our system of recording this intermediate notation in terms of runtime performance and also the benefits it brings.