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The colonic separation mechanism in lagomorphs and some rodents, associated with caecotrophy, serves to retain microbial protein. As tropical fruits have low protein concentrations, caecotrophy could be an important microbial protein source in frugivorous rodents such as the paca (Cuniculus paca). Due to conflicting reports on the occurrence of caecotrophy in this species, we obtained digestive tracts of three adult animals and observed the behaviour of four specimens maintained on a diet of a pelleted feed (P) and a supplemental mix of fruits and sweet potato (S, a source of structural fibre). In a Latin square design, P and S were both offered either in the morning (M) or in the afternoon (A), or with one item in the morning and the other in the afternoon (SP or PS). The paca's proximal colon is characterized by a distinct furrow typical for the colonic separation mechanism of hystricomorph rodents. Caecotrophy, both "direct" (from the anus) and "indirect" (from a pile of defecated faeces), was a regular component of the paca's behavioural repertoire, and caecotrophs contained more nitrogen and less fibre than hard faeces. Higher food intake led to less overall caecotrophy. With afternoon feeding of S, the onset of caecotrophy was delayed and the proportion of indirect caecotrophy increased, with hard faeces and caecotrophs often defecated together. No indirect caecotrophy occurred on treatment M. The results suggest that the time available after ingestion of structural fibre determines the efficiency of the colonic mechanism for the separation of hard faeces and caecotrophs.

Non-invasive monitoring of stress in captive wild animals. In recent decades, concerns about the welfare of captive-bred animals have intensified and, in parallel, measures addressed to evaluating the effects of an artificial environment and animal welfare are in demand. One way to assess animal stress is to perform noninvasive monitoring by evaluating the concentration of glucocorticoid metabolites in samples of feces. This technique is safe, convenient and practical, because there is no need to immobilize the animals, and feces collection is part of the daily routine adopted in captive breeding, so it hardly disturbs the subjects. The evaluation, however, needs to be interpreted with caution, because a rise in the concentration of glucocorticoid metabolites is not always related to poor welfare. For instance, positive behaviors such as play, copula and environmental enrichment can also increase glucocorticoid production by the hypothalamic-pituitary-adrenal axis. In addition, animals with chronic stress may become habituated to their conditions and present a low production of glucocorticoid. Therefore, besides monitoring physiology, it is advisable to analyze behavioral responses to assess stress. The emergence or increase in the occurrence or frequency of behavior that is potentially indicative of stress, such as pacing and other stereotyped behaviors, may denote poor animal welfare. Therefore, in this paper we reviewed the methods used for non-invasive monitoring of physiological stress in Neotropical animals kept in captivity and highlighted the gaps to stimulate further research.Keywords: abnormal behavior, animal welfare, fecal glucocorticoids, HPA axis, stereotyped behavior.Resumo. Nas últimas décadas a preocupação com o bem-estar de animais criados em cativeiro foi intensificada e, paralelamente, houve aumento da demanda por estudos relacionados à avaliação do bem-estar desses animais. Uma das maneiras de avaliar o estresse dos animais é realizar o monitoramento não invasivo por meio da quantificação da concentração de metabólitos de glicocorticóides em amostras de fezes. Esta técnica é conveniente porque causa pouca perturbação aos animais durante a coleta das amostras, pois não há necessidade de imobilização dos animais; além disso, a coleta diária das fezes faz parte da rotina dos animais criados em cativeiro. A elevação na concentração de metabólitos de glicocorticoides, contudo, nem sempre está relacionada ao bem-estar empobrecido. Alguns exemplos confirmam que comportamentos positivos ao bem-estar dos animais, tais como brincadeira, cópula e o uso de enriquecimento ambiental também estimulam a produção e a elevação de glicocorticoides pelo eixo hipotálamo-pituitária-adrenal. Além disso, animais com estresse crônico também podem se habituar às condições do ambiente e apresentarem baixa produção de glicocorticoides. Dessa forma, além do monitoramento fisiológico, é recomendada a análise das respostas comportamentais para acessar o estresse. O aparecimento ou aumento na ocorrência ou frequência de com...

Monitoring the concentration of glucocorticoid metabolites (GCMs) in faecal samples is a non-invasive tool for physiological stress evaluation, particularly useful when studying wild species. However, both negative and positive stimuli (distress and eustress, respectively) can lead to a rise in glucocorticoids. Thus, besides validating whether GCM concentration in faeces reflects endogenous adrenal activity, we also need to identify behavioural indicators of distress to avoid misinterpretation. Therefore, we submitted four adult male spotted pacas (Cuniculus paca) to an exogenous adrenocorticotropic hormone (ACTH) challenge-test in a Latin square design (4 × 4) to monitor changes in the GCM concentration in faeces. We also aimed to describe behaviours potentially indicative of distress. We collected excreted faeces and video-recorded the animals’ behaviours for five consecutive days, one day before and four days after application of the following four treatments: 1st control (no-handling); 2nd control (intra-muscular [IM] injection of saline solution); low-dose ACTH (IM injection of 0.18 ml ACTH); and high-dose ACTH (IM injection of 0.37 ml ACTH). There was a peak in the concentration of GCM in faeces collected 24 h after the injection of the high-dose ACTH treatment. Additionally, independent of the treatments, spotted pacas spent less time on exploration and feeding states, while spending more time in the inactive but awake (IBA) state following the treatment application (challenge day). The use of GCM concentration in faecal samples together with the behavioural changes (less exploration and feeding, and more IBA) showed to be efficient as a non-invasive tool for welfare assessment of farmed spotted paca.

Aims: We tested the hypothesis that the behaviour of an individual is associated with the diversity of its gut bacteria, using the collared peccary () as a model. Pecari tajacu Methods and Results: In all, 24 adult male collared peccaries received either low-( 12) or high-fibre diet ( 12) to induce contrasting gut n = n = fermentation profiles. They were submitted to three short-term challenges, allowing us to rate the animals in a coping-style dimension named 'calmness'. At the end of the experimental period, we collected samples of peccaries' forestomach contents to characterize bacterial diversity. We found a significant positive association between individual 'calmness' z-scores and the bacterial evenness index in gut bacteria (and a similar trend with the Simpson's diversity index), suggesting a more homogeneous bacterial community of calmer individuals. We also found a positive association between fibres digestibility and gut bacterial diversity in the peccaries' forestomach, but no effect of the dietary fibre level. Conclusions: Gut bacteria evenness increases with 'calmness' z-scores, suggesting a more homogeneous bacterial community of calmer individuals, compared with the more heterogeneous of the most distressed ones. Our results also suggest associations between the digestibility of ADF with the gut bacterial diversity indices and with the relative abundance of the Actinobacteria phylum. Significance and Impact of the Study: Our data showed that the hosts' individual behavioural differences are potentially aligned with gut bacterial diversity. The behaviour-microbiota link is correlated with host feed efficiency and, ultimately, may have implications for animal health and welfare of farm animals.