Putting zoo animal cancer into perspective.

As part of a comparative research agenda that promises insights that help extend the human lifespan and combat cancer, cancer prevalence in zoo animals has received recent attention. Here, we want to draw attention to a principle of cancer research that was introduced into the zoo world as early on as 1933, but that seems to have gone somewhat forgotten: Cancer is mainly a disease of old age, and therefore studies aiming at identifying taxa that are particularly susceptible or resistant to cancer must control for whether the respective zoo populations are 'old.' In a comparative context, 'old age' cannot be measured in absolute terms (e.g., years), but only in relation to a species' maximum lifespan: Species that achieve, across zoos, a higher mean lifespan as a percent of their maximum lifespan are 'older.' When applying this metric to former as well as more recently published data on cancer prevalence, it appears that those species that become relatively old in zoos-in particular, the carnivores-have a relatively high cancer prevalence. Any improvement in animal husbandry-which reduces premature deaths-should, by default, lead to more cancer. Cancer in zoo animals, like any other old-age condition, might therefore be embraced as a proxy for good husbandry. Rather than following a sensationalist approach that dramatizes disease and death per se, zoos should be clear about what their husbandry goals are, what relative longevities they want to achieve for which species, and what old-age diseases they should therefore expect: in the end, one has to die of something.

Evaluation of Disinfection Methods for Artificial Plants in Zebrafish (Danio rerio) Recirculating Water Systems.

The use of artificial plants as environmental enrichment for zebrafish (Danio rerio) in biomedical research facilities has been shown to provide benefits in animal welfare and care. Despite the benefits of artificial plants to zebrafish welfare, some research facilities are hesitant to incorporate them into their routine husbandry practices due to concerns about disease transmission and a lack of guidance on effective disinfection practices between tanks. Limited published information is available on how to adequately disinfect artificial plants, which creates concerns regarding their reuse between tanks in recirculating water systems. Proper sanitation and disinfection of these items is crucial to preventing the spread of disease in the system. We evaluated 2 disinfection methods- a commercial-grade laboratory glassware dishwasher and an ethylene oxide (ETO) sterilizer-by using ATP detection and bacterial culture of the artificial plants before and after the disinfection process. Plants were placed in the dirty sump of 2 separate recirculating systems (2,500 to 3,000 fish per system) for 2 wk before the start of the study. High ATP levels and various bacterial organisms were detected prior to disinfection. The commercial-grade labo- ratory glassware dishwasher and ETO sterilizer both significantly reduced ATP levels and resulted in complete eradication of live bacteria that were present before treatment. This study demonstrates 2 effective methods for disinfecting artificial plants in zebrafish facilities.

A Clinical Trial on the Welfare Effects of Administering Meloxicam to 10 to 21 Day Dairy Calves Following Caustic Paste Disbudding.

Caustic paste disbudding (CPD) is widely utilized for calves, which has been known to result in adverse effects on the calves and ethical concerns related to animal welfare, despite the use of local anesthetics. The administration of meloxicam has been demonstrated to provide benefits in alleviating pain and inflammation in juvenile calves under 9 d old and subjected to CPD. Nonetheless, there is a scarcity of literature documenting the beneficial impact of meloxicam in alleviating pain in calves aged over 9 d that have undergone CPD. Therefore, the objective of this clinical trial was to evaluate the efficacy of administering meloxicam and lidocaine for cornual nerve block together in mitigating the deleterious effects of CPD, as opposed to using lidocaine alone in calves older than 9 d. Thirty Holstein calves, aged between 10 and 21 d, were enrolled and randomly assigned to 1 of 2 treatments: lidocaine alone (Placebo), lidocaine and normal saline treatment before CPD, and lidocaine plus meloxicam, lidocaine and 0.5 mg/kg of meloxicam treatment prior to CPD. The researchers were blind to the treatment of calves to control the subjective error. The occurrences of actions associated with pain, which included head shaking, head rubbing, ear flicking, tail flicking, kicking, and head passing through the fence, were recorded. Physiological performance, including the respiration rate, heart rate, rectal temperature, mechanical nociceptive threshold (MNT), food intake, and daily activity level, was monitored. Hematological conditions were ascertained through the use of routine blood tests and enzyme-linked immunosorbent assay. The generalized linear mixed model was employed to analyze the data. The research findings revealed that applying the CPD procedure significantly elevated the frequencies of tail flicking, head shaking, and kicking, resulted in increases in respiratory rate, heart rate, daily active steps, and food intake and a decrease in MNT, and led to alterations in hematological markers, including platelet counts, mean platelet volume, prostaglandin E2, constitutive nitric oxide synthase, and hydroxyl radical. Considerable benefits, such as lower heart rates, higher food intake, and MNTs, as well as lower levels of white blood cell counts, lymphocyte counts, hemoglobin, mean platelet volume, prostaglandin E2, tumor necrosis factor-α, constitutive nitric oxide synthase, malondialdehyde, and hydroxyl radical, were observed in the calves that received meloxicam treatment in response to CPD. The findings of the study indicate that the co-administration of lidocaine and meloxicam provides obvious benefits in mitigating pain, inflammation, and oxidative stress in calves aged over 9 d and undergoing CPD. This endorses the use of meloxicam during the disbudding and dehorning procedures of calves.

Caustic paste disbudding (CPD) is a widely used practice in the cattle industry, yet there is a shortage of literature on the effects of meloxicam on calves aged 10 to 21 d who have undergone this procedure. In this clinical trial, we conducted a comparative analysis of the pain-related behavioral, physiological, and hematological performance of calves that were administered with either lidocaine plus normal saline (n = 15) or lidocaine plus meloxicam (n = 15) before undergoing disbudding operations. The findings demonstrated that the CPD operation had a significant impact on the pain-related behavior, physiological functions, and serum anti-inflammatory and antioxidative markers of the calves. On the other hand, the administration of meloxicam had notable advantages for the calves by enhancing the physiological and hematological parameters.

Disease Animal Models for Cancer Research.

Despite nonanimal methods (NAMs) are more and more exploited and new NAMs are developed and validated, animal models are still used in cancer research. Animals are used at multiple levels, from understanding molecular traits and pathways, to mimicking clinical aspects of tumor progression, to drug testing. In vivo approaches are not trivial and involve cross-disciplinary knowledge: animal biology and physiology, genetics, pathology, and animal welfare.The aim of this chapter is not to list and address all animal models used in cancer research. Instead, the authors would like to guide experimenters in the strategies to adopt in both planning and performing in vivo experimental procedures, including the choice of cancer animal models.

Evaluation of Cage Mate-induced Postsurgical Trauma in Mice.

Although mice are social animals, individual housing is sometimes requested after surgery. We questioned whether pair-housing mice after surgery resulted in greater trauma to the surgical site as compared with single housing. We further evaluated the effect of individual housing after surgery on the wellbeing of mice that had previously been pair-housed. Female C57Bl/6 mice (age, 6 to 8 wk) were housed as follows: group A, individually housed before and after surgery (n = 10; all 10 mice underwent surgery); group B, pair-housed before surgery but individually housed after surgery (n = 10; all 10 mice received surgery); group C, pair-housed before and after surgery (n = 20; 10 mice underwent surgery but their cage mates did not); and group D, pair-housed before and after surgery (n = 10; all 10 mice underwent surgery). Dependent variables were body weight, body condition, grimace based on real-time scoring, nest building, time to incorporate into nest test (TINT) score, wound trauma score, and missing wound clips. Weight was significantly different between groups A and C both before and after surgery. Mean nest building scores were significantly higher for pair-housed (groups C and D) than for individually housed mice (groups A and B) after surgery while TINT scores were significantly higher for these same groups both before and after surgery. Mean values for body condition, grimace score, wound score, and number of wound clips missing did not differ significantly between any groups either before or after surgery. Taken together, these results suggest that pair housing mice after surgery benefited their wellbeing but did not increase trauma to the surgical incision site or disturb wound clips as compared with individually housed mice. Furthermore, separating previously pair-housed mice (group B) did not affect these measures as compared with individually housed mice (Group A) either before or after surgery.

Pre-slaughter, slaughter and post-slaughter practices of slaughterhouse workers in Southeast, Nigeria: Animal welfare, meat quality, food safety and public health implications.

BACKGROUND: Pre-slaughter stress or the welfare condition of food-producing animals (FPAs) and the slaughter practices of slaughterhouse workers (SHWs) are critically important for the safety and quality of meats processed in slaughterhouses (SHs). Consequently, this study determined the pre-slaughter, slaughter, and post-slaughter (PSP) practices of SHWsin four SHs in Southeast, Nigeria; and discussed the impacts on meat quality and safety. METHODS: The PSP practices were determined by observation method. Additionally, a structured and validated closed-ended questionnaire was used to determine the knowledge of the SHWs on: the effects of poor welfare (preslaughter stress) on the quality and safety of meats produced, carcass/meat processing practices and modes of transmission of meat-borne zoonotic pathogens during carcass/meat processing. Finally, a systematic post-mortem inspection (PMI) was conducted on cattle, pigs and goats slaughtered, and economic losses accruable from condemned carcasses/meats were estimated. RESULTS: Food-producing animals were transported to the SHs or held in the lairage under inhumane conditions. A pig being conveyed to one of the SHs was seen gasping for air, as it was firmly tied on motorbike at the thoracic and abdominal regions. Fatigued cattle were forcefully dragged on the ground from the lairage to the killing floor. Cattle for slaughter were restrained, held in lateral recumbency and left groaning, due to extreme discomfort, for about one hour before slaughter. Stunning was not performed. Singed pig carcasses were dragged on the ground to the washing point. Although more than 50% of the respondents knew the modes of transmission of meat-borne zoonotic pathogens during meat processing, 71.3% of the SHWs processed carcasses on bare floor, 52.2% used same bowl of water to wash multiple carcasses while 72% did not wear personal protective equipment during meat/carcass processing. Processed meats were transported to meat shops in an unsanitary conditions, using open vans and tricycles. During the PMI, diseased carcasses/meats/organs were detected in 5.7% (83/1452), 2.1% (21/1006) and 0.8% (7/924) of the cattle, pig and goat carcasses inspected, respectively. Gross lesions pathognomonic of bovine tuberculosis, contagious bovine pleuro-pneumonia, fascioliasis and porcine cysticercosis were detected. Consequently, 391,089.2 kg of diseased meat/organs valued at 978 million Naira (235, 030 USD) were condemned. There were significant associations (p < 0.05) between educational level and the use of personal protective equipment (PPE) during slaughterhouse operations and knowledge that FPAs can harbour zoonotic pathogens (p = < 0.001) transmissible during carcass processing. Similarly, significant association was observed between working experience and use of PPE; and between geographical location of the respondents and knowledge that zoonotic pathogens in animals are transmissible during carcass processing or via the food chain. CONCLUSION: The findings show that slaughter practices of SHWs have detrimental impacts on the quality and safety of meats processed for human consumption in Southeast, Nigeria. These findings underscore the need to: improve the welfare condition of slaughter-animals, mechanise abattoir operations, train and retrain the SHWs on hygienic carcass/meat processing practices. There is a need to adopt strict enforcement of food safety laws to promote meat quality, food safety and consequently promote the health of the public.

Method of measuring effects of study procedures in single and pair housed New Zealand White rabbits (Oryctolagus cuniculus).

Social housing of laboratory rabbits is encouraged and thought to improve animal welfare due to the social nature of this species. However, there is limited published information comparing the physiologic and cardiovascular (CV) effects of paired and single housed adult female rabbits in commonly used laboratory caging. This study describes measurement of heart rate, systolic blood pressure, activity level, body temperature and pairing methods in four female New Zealand White rabbits that were previously implanted with M10 cardiovascular telemetry devices. Data was collected in single housed rabbits having no history of social housing while they were undisturbed in the home cage, during restraint, intramuscular injections and intravenous blood collection. The same animals were then placed in compatible pairs and housed in conventional Allentown caging. As expected, we found increased activity in paired rabbits but no significant differences in body temperatures, and CV parameters in single and paired rabbits undergoing the same procedures. These data suggest that paired rabbits can be used for safety pharmacology studies with minimal impact to data, while supporting improved animal welfare.

Measuring the effectiveness of using rangers to deliver a behavior change campaign on sustainable palm oil in a UK zoo.

A fundamental objective of modern zoos is promoting pro-environmental behaviors. This study experimentally assessed the contribution of zoo rangers (staff employed to engage visitors) in delivering a behavior change campaign promoting sustainable palm oil use. The campaign was delivered in a dedicated area in a walk-through animal exhibit, with rangers either "present" or "absent" in the campaign space. Questionnaires assessing awareness, knowledge, and purchasing intentions were completed by 1032 visitors. Two analyses were conducted: (1) comparing the impact of ranger presence versus absence (to assess the overall impact of having rangers present regardless of whether they talked to visitors) and (2) comparing the impact of talking to a ranger against demographically matched individuals visiting when rangers were absent (to assess the specific impact of talking to a ranger). Visitors who talked to rangers were more aware of palm oil, had more knowledge, and greater intentions of purchasing sustainable palm oil. However, as only one-quarter of visitors talked to a ranger, fewer differences were found comparing ranger presence versus absence. These findings suggest that rangers can be instrumental in communicating complex conservation issues and delivering zoo-based behavior change campaigns, but their impact is limited by low engagement rates.

Key points for the thermal comfort of water buffaloes in Eastern Amazon / Pontos-chave do conforto térmico de bubalinos na Amazônia Oriental

This study presented relevant aspects about the Amazonian environment and how it impacts the thermal comfort of domestic buffaloes (Bubalus bubalis) raised in the Eastern Amazon. Furthermore, strategies for monitoring and mitigating animal heat stress are presented, based on research results with the species. Although domestic buffaloes are considered adaptable animals, exposure to intense solar radiation causes thermal discomfort. This condition is expressed in biophysical indicators, in metabolic, endocrine, behavioral responses, and in body thermographic patterns. Therefore, the biometeorological monitoring of production is crucial to support decision-making regarding environmental management strategies, genetic selection of thermotolerant individuals, and increase in animal welfare. Lastly, the use of silvopastoral systems can help to provide higher thermal comfort, which is a condition that directly impacts the productivity of milk and meat buffaloes when they are raised in tropical regions, such as in the Eastern Amazon.

Objetivou-se apresentar aspectos relevantes sobre o ambiente amazônico e como este impacta no conforto térmico de búfalos domésticos (Bubalus bubalis) criados na Amazônia Oriental. Adicionalmente, são apresentadas estratégias para monitoramento e mitigação do estresse térmico animal, a partir de resultados de pesquisa com a espécie. Apesar dos búfalos domésticos serem considerados animais adaptáveis, a exposição à intensa radiação solar provoca desconforto térmico. Essa condição é expressa em indicadores biofísicos, nas respostas metabólicas, endócrinas, comportamentais e nos padrões termográficos corporais. Assim, o monitoramento biometeorológico da produção é crucial para subsidiar tomadas de decisão em relação a estratégias de manejo ambiental, seleção genética de indivíduos termotolerantes e incremento do bem-estar animal. Por fim, o uso de sistemas silvipastoris pode auxiliar na oferta de maior conforto térmico, que é uma condição que impacta diretamente na produtividade de bubalinos de leite e carne, quando estes são criados em regiões tropicais, como na Amazônia Oriental.

Survey of euthanasia methods used in neotropical chiropterans in São Paulo State, Brazil: critical analyses and proposal for standardization of bat euthanasia methods / evantamento dos métodos de eutanásia utilizados em quirópteros neotropicais no estado de São Paulo, Brasil: análise crítica e proposta de padronização de métodos de eutanásia em morcegos

Zoonotic Surveillance Divisions (ZSDs) rescue and euthanize bats in contact with humans. The euthanasia procedure should be conducted safely for the animal and caretaker and minimal stress for the animal is important. The objectives of this study were: i. evaluate the methods of euthanasia used by ZSDs in the State of São Paulo; ii. compare the methods with national and international guidelines for animal euthanasia practices; iii. assess the methodologies considering taxonomy and eating habits of the main bat species, and iv. propose standardization of euthanasia procedures. Sixty-five ZSDs locations received an online questionnaire or were contacted by telephone and 33 ZSDs (50.8%) responded and are distributed in 11 mesoregions in the state to remain anonymous. The euthanasia methods were divided into chemical (injectable or inhalation), physical, or mixed methods. Bat specimens (n = 550) were identified and classified to evaluate the main genera found in the state. The location of the ZSD, species, eating habits, and the method of euthanasia used were analyzed. The specimens by bat families were Molossidae (n = 340), Phyllostomidae (n = 171), and Vespertilionidae (n = 39). Chemical methods were used in 25 ZSDs (75.75%), physical in 5 (15.15%), and mixed in 3 (9.09%). There is no uniformity or standardization in bat euthanasia methods used by ZSDs, although most are based on acceptable chemical methods. It was proposed an algorithm to assist the veterinarian in choosing the method of euthanasia for bats that will allow standardizing euthanasia procedures for this species, considering physiological differences, and respecting technical, bioethical, and animal welfare guidelines.(AU)

As Divisões de Vigilância de Zoonoses (DVZs) coletam e eutanasiam morcegos que tiveram contato com humanos. O procedimento de eutanásia precisa ocorrer de modo seguro para o animal e para o manipulador, sendo importante garantir o mínimo de estresse ao animal. Os objetivos deste estudo foram: i. avaliar os métodos de eutanásia praticados nas DVZ do estado de São Paulo; ii. comparar esses métodos com os guias nacionais e internacionais de práticas de eutanásia animal; iii. avaliar as metodologias aplicadas considerando a taxonomia e os hábitos alimentares das principais espécies de ocorrência de morcegos; e iv. propor a padronização dos procedimentos de eutanásia. Sessenta e cinco DVZs receberam o questionário online ou foram contatadas por telefone, dessas, trinta e três DVZs (50,8%) que responderam ao questionário foram incluídas no estudo e distribuídas em 11 mesorregiões para garantir anonimato. Os métodos de eutanásia reportados foram divididos em métodos químicos (injetáveis; inalatórios), físicos ou mistos. Os espécimes de morcegos (n = 550) foram identificados e classificados para avaliar os principais gêneros encontrados no estado. A localização da DVZ, as espécies, os hábitos alimentares e o método de eutanásia utilizado foram analisados. Os espécimes por família de espécies de morcegos foram Molossidae (n = 340), Phyllostomidae (n = 171) e Vespertilionidae (n = 39). Métodos químicos foram utilizados em 25 DVZs (75,75%), físicos em 5 (15,15%) e mistos em 3 (9,09%). Não há uniformidade ou padronização nos métodos de eutanásia de morcegos, embora a maioria seja baseada em métodos químicos aceitáveis. É proposto um algoritmo para auxiliar o veterinário na escolha do método de eutanásia, que permite a padronização desses procedimentos para os morcegos, considerando as diferenças fisiológicas e respeitando as diretrizes técnicas, bioéticas e de bem-estar animal.(AU)

Behavioral assessment of Tambaqui juveniles (Colossoma macropomum) exposed to different ambient colors and social stress

Animal welfare regards the quality of life and the environment in which animals live or are exposed. Hence the importance of studies assessing the environmental influence on the biology and behavior of fishes from the Colossoma macropomum species, considering their higher potential for fish-farming and as a test organism in scientific research. This study aimed to assess, in a controlled environment, the behavioral changes expressed by juveniles from the Colossoma macropomum species exposed to different ambient colors or social situations. The results did not show an influence from the different ambient colors or social situations on fish distribution in the water column. The color pattern showed dark tones in black- and blue-colored environments, and light tones in white-colored environments or with the presence of a mirror. The time of locomotor activity/frequency did not change in any of the treatments of exposure to environments with colors and a mirror. Moreover, the fishes remained with folded fins and a straight posture, maintaining a pattern of rhythmic operculum beating in a normal frequency range described for the species. This suggests that animal welfare did not change in any of the situations tested and that there was a pattern of adaptive response to the type of environment.

The Current Status and Work of Three Rs Centres and Platforms in Europe.

The adoption of Directive 2010/63/EU on the protection of animals used for scientific purposes has given a major push to the formation of Three Rs initiatives in the form of centres and platforms. These centres and platforms are dedicated to the so-called Three Rs, which are the Replacement, Reduction and Refinement of animal use in experiments. ATLA's 50th Anniversary year has seen the publication of two articles on European Three Rs centres and platforms. The first of these was about the progressive rise in their numbers and about their founding history; this second part focuses on their current status and activities. This article takes a closer look at their financial and organisational structures, describes their Three Rs focus and core activities (dissemination, education, implementation, scientific quality/translatability, ethics), and presents their areas of responsibility and projects in detail. This overview of the work and diverse structures of the Three Rs centres and platforms is not only intended to bring them closer to the reader, but also to provide role models and show examples of how such Three Rs centres and platforms could be made sustainable. The Three Rs centres and platforms are very important focal points and play an immense role as facilitators of Directive 2010/63/EU 'on the ground' in their respective countries. They are also invaluable for the wide dissemination of information and for promoting the implementation of the Three Rs in general.

Consumers' Attitudes towards Animal Suffering: A Systematic Review on Awareness, Willingness and Dietary Change.

Planetary and human health depend on Westerners' ability to reduce meat consumption. Meat production degrades the environment while excessive meat intake is associated with cancer and cardiovascular disease, among others. Effective reasons and motivations are needed for consumers to change their diet. The fact that modern animal agriculture inflicts a great deal of pain on animals from their birth to their slaughter, animal welfare/suffering may drive consumers to curtail their meat consumption. This systematic review examined a total of 90 papers to ascertain consumers' awareness of the pain animals experience in animal agriculture, as well as consumer attitudes towards meat reduction due to animal welfare. Results show that consumers have low awareness of animal agriculture. Awareness of animal agricultural practices and animal sentience is associated with increased negative attitudes towards animal suffering. Animal suffering due to farming practices, transportation, slaughter, and animal sentience are factors that may encourage a reduction in meat consumption, and even dietary change in the short term. There is also evidence that animal suffering may be a more compelling motivation for consumers' willingness to change their diet than for health or environmental reasons. Therefore, increasing consumers' awareness of animal suffering in meat production is paramount to contributing to reduced pressure on the environment and improved human health.

New trends in immunocastration and its potential to improve animal welfare: a mini review.

Castration is frequently used to reduce aggressive behavior and improve the meat quality of animals. Traditionally, surgical and mechanical castration are used to sterilize the animals, but these approaches are associated with a high level of pain, stress, long recovery periods, and post-operative infections. Immunocastration is a new animal-friendly, painless alternative castration technique that is used to prevent undesired sexual behavior, reduce aggressive behavior, prevent unwanted pregnancy, control wildlife populations and wandering species, enhance growth performance, improve meat quality, and treat various sex hormone-dependent disorders. The mechanism of immunocastration includes the immunological block of the hypothalamic-pituitary-gonadal axis (HPG axis) which inhibits gonadotropin secretions, causes atrophy of gonadal tissues, and inhibits gametogenesis, resulting in infertility in both female and male mammals. By the mid-1990s, various immunocastration vaccines have been tested in different animal models to achieve successful castration effects. Recently, genetic immunocastration especially DNA vaccine has gained increasing attention due to its safety, being animal-friendly, and being easy to use. This review aims to evaluate the potential of traditional castration methods, as well as the current status of immunocastration vaccines, their effects, and future prospective.

2022 AAFP/ISFM Cat Friendly Veterinary Interaction Guidelines: Approach and Handling Techniques.

PRACTICAL RELEVANCE: The '2022 AAFP/ISFM Cat Friendly Veterinary Interaction Guidelines: Approach and Handling Techniques' (hereafter the 'Cat Friendly Veterinary Interaction Guidelines') support veterinary professionals with feline interactions and handling to reduce the impact of fear and other protective (negative) emotions, in so doing enhancing feline welfare and In implementing these Guidelines, team satisfaction and cat caregiver confidence in the veterinary team will increase as the result of efficient examinations, better experience, more reliable diagnostic testing and improved feline wellbeing. Veterinary professionals will learn the importance of understanding and appropriately responding to the current emotional state of the cat and tailoring each visit to the individual. CLINICAL CHALLENGES: Cats have evolved with emotions and behaviors that are necessary for their survival as both a predator and prey species. A clinical setting and the required examinations and procedures to meet their physical health needs can result in behavioral responses to protective emotions. Cat friendly interactions require understanding, interpreting and appropriately responding to cats' emotional states and giving them a perceived sense of control while performing the required assessment. EVIDENCE BASE: These Guidelines have been created by a Task Force of experts convened by the American Association of Feline Practitioners and the International Society of Feline Medicine, based on an extensive literature review and, where evidence is lacking, the authors' experience. ENDORSEMENTS: These Guidelines have been endorsed by a number of groups and organizations, as detailed on page 1127 and at catvets.com/interactions and icatcare.org/cat-friendly-guidelines.

Poor body condition is associated with lower hippocampal plasticity and higher gut methanogen abundance in adult laying hens from two housing systems.

It is still unclear which commercial housing system provides the best quality of life for laying hens. In addition, there are large individual differences in stress levels within a system. Hippocampal neurogenesis or plasticity may provide an integrated biomarker of the stressors experienced by an individual. We selected 12 adult hens each with good and poor body condition (based on body size, degree of feather cover and redness of the comb) from a multi-tier free range system containing H&N strain hens, and from an enriched cage system containing Hy-Line hens (n = 48 total). Immature neurons expressing doublecortin (DCX) were quantified in the hippocampus, contents of the caecal microbiome were sequenced, and expression of inflammatory cytokines was measured in the spleen. DCX+ cell densities did not differ between the housing systems. In both systems, poor condition hens had lower DCX+ cell densities, exhibited elevated splenic expression of interleukin-6 (IL6) mRNA, and had a higher relative caecal abundance of methanogenic archea Methanomethylophilaceae. The findings suggest poor body condition is an indicator that individual hens have experienced a comparatively greater degree of cumulative chronic stress, and that a survey of the proportion of hens with poor body conditions might be one way to evaluate the impact of housing systems on hen welfare.

Refinements to rodent head fixation and fluid/food control for neuroscience.

The use of head fixation in mice is increasingly common in research, its use having initially been restricted to the field of sensory neuroscience. Head restraint has often been combined with fluid control, rather than food restriction, to motivate behaviour, but this too is now in use for both restrained and non-restrained animals. Despite this, there is little guidance on how best to employ these techniques to optimise both scientific outcomes and animal welfare. This article summarises current practices and provides recommendations to improve animal wellbeing and data quality, based on a survey of the community, literature reviews, and the expert opinion and practical experience of an international working group convened by the UK's National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs). Topics covered include head fixation surgery and post-operative care, habituation to restraint, and the use of fluid/food control to motivate performance. We also discuss some recent developments that may offer alternative ways to collect data from large numbers of behavioural trials without the need for restraint. The aim is to provide support for researchers at all levels, animal care staff, and ethics committees to refine procedures and practices in line with the refinement principle of the 3Rs.