Exploiting flavour preferences of common marmosets to increase palatability of a dry pellet diet

Although commercially available complete diets exist for common marmosets, the animals’ consumption of these diets (available in dry pellet form) is typically very low. Increasing consumption of the pellet diet could have positive consequences for the welfare of the marmosets as the pellets are designed specifically to meet their full nutritional requirements, and therefore an increase in intake should help to ensure that they take in an appropriate balance of nutrients. We carried out a series of studies targeted towards improving the palatability, and hence increasing the intake, of a complete dry pellet diet for marmosets. In Study 1 we attempted to determine which of a wide range of flavours appeared to be preferred by the marmosets. In Study 2 we tested the marmosets’ preferences for a smaller number of highly preferred flavours (as determined in Study 1) when actually added to the dry pellet diet in a series of paired preference tests. Finally, in Study 3 we tested whether adding the most highly preferred flavours (as determined in Study 2) to the dry pellet diet would in fact increase consumption of these pellets in comparison with unflavoured pellets. Despite finding strong and consistent preferences for particular flavours amongst the marmosets, we found that adding these to the pellets did not significantly increase consumption. Reasons for this are discussed, along with other potential modifications which might prove more successful in increasing consumption of pellet diets for marmosets.     

Equality without equivalence: an anthropology of the common

This article elaborates an Amazonian conception of the common and the challenge it poses to Western thinking about individualism and equality. It is suggested that a number of distinctive features of Amazonian Urarina sociality may have their basis in a shared refusal of factors that give rise to relations of equivalence between people. This kind of singularism, or ‘individualism without individuals’, results from an orientation to the common as a collective resource that is antithetical to property, in which subjectivity is shaped in relation to wider ecological and affective resources that are continuously and collectively produced. This embraces not only shared economic resources, such as land or game animals, but also ways of organizing and producing affective, cognitive, and linguistic relations, ‘commonalities’ of various kinds which never reduce differences to an abstract subject, such as the individual of liberalism or the collective of socialism.     

The role of common reinforced comparison responses in acquired sample equivalence

Different samples occasioning the same reinforced comparison response in matching-to-sample are interchangeable for one another outside of original training. The present studies were designed to verify the role of these common responses in producing acquired sample equivalence by explicitly varying the presence or absence of this commonality during training. In each of the two experiments, one group of pigeons made the same reinforced choice response following multiple sample stimuli, whereas controls either made different reinforced choices following each sample (Experiment 1) or reinforced choices after only two of four center-key stimuli (Experiment 2). Later, two of the original samples/center-key stimuli were established as conditional cues for new comparison responses, after which the ability of the remaining samples/center-key stimuli to occasion those new responses was assessed. Following common-response training, matching accuracy was higher on class-consistent than on class-inconsistent transfer tests, whereas accuracy in the controls was generally intermediate between these two extremes, a pattern similar to that reported in the human paired-associate literature. These findings confirm that occasioning the same reinforced choice response is one means by which disparate samples become functionally equivalent.     

Acquired immunity in rats against Angiostrongylus cantonensis infection

Acquired immunity against Angiostrongylus cantonensis was induced by immunizing rats with somatic antigens from fifth-stage larvae and adult worms and live third-stage larvae. Rats immunized twice had significantly fewer worms than rats immunized three times. Fewer worms were recovered from rats immunized with 200 live third-stage larvae than from any other groups. Rats immunized with somatic antigens had higher enzyme-linked immunosorbent assay (ELISA) antibody levels than rats immunized with live larvae. Rats immunized with live third-stage larvae of Angiostrongylus cantonensis were more strongly protected against challenge infections (62-92%) than rats immunized with antigens extracted from fifth-stage larvae (0-30%) and adult worms (11-24%).     

The role of contextual cues in operant responding in rats

Following lever-press training on a variable-interval 60-second schedule of food presentation, groups of rats either remained in their home cages or were exposed to the operant chamber, from which lever and food had been removed, for five sessions. The lever was replaced in the chamber and rats from Group 1 (exposure to chamber) and Group 3 (home cage) were returned to the variable-interval schedule. Although response rates in test sessions were somewhat lower than at the end of training, there was no statistically significant difference in rates for either group. Rats in Group 2 (exposure to chamber) and Group 4 (home cage) received two test sessions of extinction. During the first session, Group 2 rates of lever pressing were significantly higher than Group 4 rates. These findings do not support the view that associations between contextual cues and the reinforcer serve to energize instrumental behavior (Pearce & Hall, 1979), and provide only minimal support for the view that contextual cues control responses that compete with the operant (Mills, 1980).     

Acquired hemophilia in a patient with myeloma.

The generally accepted indications for stress testing in patients with coronary artery disease include confirming the diagnosis of angina, determining the limitation of activity caused by angina, assessing prognosis in patients with known coronary artery disease, assessing perioperative risk, and evaluating responses to therapy. In patients with a clinical scenario strongly suggestive of angina, testing is not necessary to diagnose coronary artery disease. The exercise treadmill-electrocardiogram test is the oldest and most extensively used stress test and can be reliably performed in patients who are clinically stable and who have an interpretable resting electrocardiogram. The addition of myocardial imaging agents such as thallium 201, technetium Tc 99m sestamibi, and technetium Tc 99m teboroxime increases the sensitivity and specificity for detecting coronary disease. Pharmacologic agents such as dipyridamole, adenosine, and dobutamine may be used in patients who cannot exercise adequately. Myocardial ischemia can also be evaluated by echocardiography, computed tomography, or magnetic resonance imaging, especially when additional information such as left ventricular and valvular function is desired. We review the indications for the noninvasive evaluation of coronary artery disease and the rationale for selecting a diagnostic test.     

Association of antecedent malnutrition with persistent diarrhoea: a case-control study.

To determine the effect of nutritional state on persistent diarrhoea a case-control study was carried out on 756 children followed up prospectively for 18 months. Children who developed persistent diarrhoea were compared with population controls and controls with acute diarrhoea. The mean weight for age in the children with persistent diarrhoea (69.9%) was significantly lower than that in the population controls (77.0%) and the diarrhoeal controls (76.2%). Weight for age of less than or equal to 70% was associated with persistent diarrhoea in both case-control analyses (population controls, matched odds ratio 3.25; diarrhoeal controls, matched odds ratio 2.46). The corrected odds (multiple logistic regression) in the two analyses were 3.2 (95% confidence interval 1.3 to 8.1) and 3.4 (1.2 to 9.1). Weight for age of less than or equal to 70% increases the risk of persistent diarrhoea. In an underweight child there is a higher risk of diarrhoea becoming persistent. Prevention of malnutrition and intensive management of acute diarrhoea in malnourished children should help reduce the risk of the diarrhoea persisting.     

Learning of auditory equivalence classes for vowels by rats

Four male Long-Evans rats were trained to discriminate between synthetic vowel sounds using a GO/NOGO response choice task. The vowels were characterized by an increase in fundamental frequency correlated with an upward shift in formant frequencies. In an initial phase we trained the subjects to discriminate between two vowel categories using two exemplars from each category. In a subsequent phase the ability of the rats to generalize the discrimination between the two categories was tested. To test whether rats might exploit the fact that attributes of training stimuli covaried, we used non-standard stimuli with a reversed relation between fundamental frequency and formants. The overall results demonstrate that rats are able to generalize the discrimination to new instances of the same vowels. We present evidence that the performance of the subjects depended on the relation between fundamental and formant frequencies that they had previously been exposed to. Simple simulation results with artificial neural networks could reproduce most of the behavioral results and support the hypothesis that equivalence classes for vowels are associated with an experience-driven process based on general properties of peripheral auditory coding mixed with elementary learning mechanisms. These results suggest that rats use spectral and temporal cues similarly to humans despite differences in basic auditory capabilities.     

The energetic equivalence rule rejected because of a potentially common sampling error: evidence from carabid beetles

Abundance data from pitfall traps are widely used to estimate the relationship between beetle body size and abundance. Such data probably overestimate densities of large bodied species and may overestimate slopes of size‐abundance relationships. Here, we test this idea by comparing size‐abundance patterns found using data from pitfall trapping with those found with data from a quantitative method of estimating abundance, quadrat sampling. We use data from a total of 47 communities. As expected, slopes of size‐abundance relationships are significantly more positive when estimated using data from pitfall traps compared to when using quadrat sampling data. This was seen when looking across different communities, within communities sampled by both methods and when focusing on the set of species found by both methods within a community. These results were also generally found regardless of method of analysis, which were done using regression with species values as independent data points and using the independent contrast method, and with slopes estimated using ordinary least square regression or the structural relation. Most important, slopes of size‐abundance relationships based on data from pitfall traps were on average significantly more positive than ?0.75 on log–log scales, and thus inconsistent with the energetic equivalence rule. Slopes based on quadrat sampling, on the other hand, were on average not significantly different from ?0.75. The rejection of the energetic equivalence rule based on data from pitfall traps here is therefore a sampling artefact. Similar problems may apply to abundance data from virtually all insect trapping methods, and should make us consider re‐examining many of the size‐abundance patterns documented so far. As a large proportion of all animal species are insects, and traps are widely used to estimate abundance, this is a potentially important problem for our general understanding of the relationship between species body size and abundance.     

Sensory cues mediating mating-induced potentiation of sexual receptivity in female rats

Repeated mating of estradiol-primed female rats increases sexual receptivity. Two studies were conducted to determine the contribution of vaginal--cervical stimulation (VCS) to this increase. In the first study, female rats were repeatedly mated for 165 min. The vaginas of half of the females were covered with tape (masked) to prevent intromissions by the males. The remaining females were unmasked. Only females receiving intromissions (unmasked) showed a significant increase in sexual receptivity during repeated mating, suggesting that VCS from intromissions is necessary for repeated mating to increase sexual receptivity. In the second experiment, female rats received either experimentally administered VCS or control scapular stimulation administered with a plastic probe 1 h prior to testing for sexual receptivity. VCS applied in this manner significantly increased sexual receptivity. Together, these findings suggest that VCS from intromissions is one of the primary factors responsible for increases in sexual receptivity following repeated mating.     

Eastern bluebirds Sialia sialis do not avoid nest boxes with chemical cues from two common nest predators

Chemodetection of common nest predators may be advantageous for nesting birds; however, few studies have examined the ability of songbirds to detect chemical odors from predators. Thus, in 2002, we presented eastern bluebirds Sialia sialis with pairs of nest boxes; one box in the pair was regularly scented with chemical cues from a common nest predator, the black rat snake Elaphe obsoleta , and the other with a neutral cue. In 2004, we again presented bluebirds with pairs of boxes, one scented with chemical cues from a different nest predator, the deer mouse Peromyscus maniculatus , and the other with a neutral scent. Although human females were able to correctly distinguish paper laced with predator cues from paper with neutral cues, bluebirds were as likely to lay eggs in boxes with predator cues as in boxes with neutral cues. While it remains possible that bluebirds may detect scent from potential nest predators, it appears that the presence of these chemical cues does not ultimately influence selection of nest sites.     

PCR identification of Trypanosoma lewisi,a common parasite of laboratory rats

Trypanosoma (Herpetosoma) lewisi is a trypanosome of the sub-genus Herpetosoma (Stercoraria section), parasite of rats (Rattus rattus and Rattus norvegicus) transmitted by fleas. T. lewisi has a stringent species specificity and cannot grow in other rodents such as mice. Rats are infected principally by oral route, through contamination by flea faeces or ingestion of fleas. Trypanosoma lewisi infections in rat colonies can interfere with research protocols and fleas of wild rats are often the source of such infections. Currently, diagnosis of T. lewisi in rats is performed by microscopic observation of stained blood smears. In the course of a research project at CIRDES, a T. lewisi infection was detected in the rat colony. In this study we evaluated PCR primer sets for their ability to diagnose multiple species of trypanosomes with a single amplification. We show that the use of ITS1 sequence of ribosomal DNA provides an efficient and sensitive assay for detection and identification of T. lewisi infection in rats and recommend the use of this assay for monitoring of T. lewisi infections in rat colonies.