Individual differences in behaviour and gut bacteria are associated in collared peccary (Mammalia, Tayassuidae).

AIMS: We tested the hypothesis that the behaviour of an individual is associated with the diversity of its gut bacteria, using the collared peccary (Pecari tajacu) as a model. METHODS AND RESULTS: In all, 24 adult male collared peccaries received either low- (n = 12) or high-fibre diet (n = 12) to induce contrasting gut 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.

Individual differences in behavior affect total tract fiber digestibility: the example of collared peccary.

Differences in how individuals cope with stressful conditions (e.g. novel/unfamiliar environment, social isolation and increases in human contact) can explain the variability in data collection from nutrient digestibility trials. We used the collared peccary (Pecari tajacu), which is under process of domestication and shows high individual behavioral distinctiveness in reactions toward humans, to test the hypothesis that behavioral differences play a role in nutrient digestibility. We assessed the individual behavioral traits of 24 adult male collared peccaries using both the 'behavioral coding' and the 'subjective ratings' approaches. For the behavioral coding assessment, we recorded the hourly frequency of behaviors potentially indicative of stress during the 30-day habituation period to the experimental housing conditions. The subjective ratings were performed based on the individuals' reactions to three short-term challenge tests (novel environment, novel object and threat from a capture net) over a period of 56 days. During the last 26 days, the collared peccaries were fed diets either high (n = 12) or low (n = 12) in dietary fiber levels, and we determined the total tract apparent digestibility of nutrients. The individual subjective ratings showed consistency in the correlated measures of 'relaxedness', 'quietness' and 'satisfaction' across the three challenge tests, which were combined to produce z score ratings of one derived variable ('calmness'). Individual frequency of BPIS/h and calmness scores were negatively correlated and both predicted the total tract digestibility of acid detergent fiber (ADF), which ranged from 0.41 to 0.79. The greater the calmness z scores (i.e. calmer individuals), the greater the total tract digestibility of ADF. In contrast, the higher the frequency of BPIS/h, the lower the total tract digestibility of ADF. Therefore, our results provide evidence that by selecting calmer collared peccaries, there will be an increase in their capacity to digest dietary fiber.

The effects of unrelated offspring whistle calls on capybaras (Hydrochoerus hydrochaeris).

Parent-offspring vocal communication, such as the isolation call, is one of the essential adaptations in mammals that adjust parental responsiveness. Thus, our aim was to test the hypothesis that the function of the capybara infants' whistle is to attract conspecifics. We designed a playback experiment to investigate the reaction of 20 adult capybaras (seven males and 13 females) to pups' whistle calls - recorded from unrelated offspring - or to bird song, as control. The adult capybaras promptly responded to playback of unrelated pup whistles, while ignoring the bird vocalisation. The adult capybaras took, on average, 2.6 ± 2.5 seconds (s) to show a response to the whistles, with no differences between males and females. However, females look longer (17.0 ± 12.9 s) than males (3.0 ± 7.2 s) toward the sound source when playing the pups' whistle playback. The females also tended to approach the playback source, while males showed just a momentary interruption of ongoing behaviour (feeding). Our results suggest that capybara pups' whistles function as the isolation call in this species, but gender influences the intensity of the response.

High prevalence of Salmonella in tegu lizards (Tupinambis merianae), and susceptibility of the serotypes to antibiotics.

Species of tegu (Tupinambis) are the largest lizards in South America. Large numbers of these lizards are hunted; there is a vigorous trade in their skins and the meat is consumed by rural and native peoples. The animals are also bred in captivity, an economic activity for rural populations which can help in the animals' conservation. Faecal samples from 30 captive-born tegus were analysed for the presence of Salmonella in two separate samplings. In the first analysis, samples from 26 animals (87%) yielded Salmonella enterica of which 23% were of Rubislaw serotype; 20% Carrau and Agona serotypes; 7% Infantis and Saint-Paul serotypes; 3% Panama and Brandenburg serotypes; 10% were S. enterica subsp. enterica and 7% were rough form. In the second analysis, four tegus (13%) which had been negative in the first sampling were positive, thus, 100% of the animals studied carried the bacterium. Antibiotic susceptibility showed resistance to sulfonamide in 82% of the isolates, streptomycin in 64%, tetracycline in 6% and Chloramphenicol in 20%. Two animals carried strains of the same serotype with different patterns of antibiotic susceptibility. Although it is well known that reptiles are a significant source of Salmonella, to our knowledge, its prevalence in tegu has not been studied previously.