85 resultados para Direct effect


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Distributive, procedural, interpersonal and informational justices were included in this study of gender differences in in-role and extra-role behavior. Distributive justice predicted performance, organizational commitment and OCB for men but only performance and job satisfaction for women. Procedural justice predicted job satisfaction for men and did not predict any outcomes for women. Informational justice predicted job satisfaction for both male and female respondents. Informational justice predicted female but not male organizational commitment and in-role performance. Interpersonal justice predicted male but not female organizational citizenship behavior. The study demonstrates important distinctions between the four organizational justice types and how men and women respond differently to those distinctions. The differences in the drivers of in-role performance between men and women may also have practical implications for managers. For example, distributive justice was a direct in-role performance driver for both genders, but informational justice provides an incremental direct effect for women.

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The effect of unions on profits continues to be an unresolved theoretical and empirical issue. In this paper, clustered data analysis and hierarchical linear meta-regression models are applied to the population of forty-five econometric studies that report 532 estimates of the direct effect of unions on profits. Unions have a significant negative effect on profits in the United States, and this effect is larger when market-based measures of profits are used. Separate meta-regression analyses are used to identify the effects of market power and long-lived assets on profits, as well as the sources of union-profit effects. The accumulated evidence rejects market power as a source of union-profit effects. While the case is not yet proven, there is some evidence in support of the appropriation of quasi-rent hypothesis. There is a clear need for further American and non-American primary research in this area.

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We examined the effects of cage size and testosterone (T) levels on basal and peak metabolic rates (BMR and PMR, respectively) and on pectoral and leg muscle masses of male house sparrows (Passer domesticus). Birds were housed either in small birdcages or in flight aviaries for at least 2 weeks prior to the initial metabolic evaluations. They were then implanted with either empty or T-filled silastic capsules and remeasured 5–6 weeks later. Birds treated with single T implants achieved breeding levels (4–6 ng/mL) and one group given double implants reached 10 ng/mL. There was no effect of T on BMR or PMR in any group studied, but there was an effect of caging. Caged birds showed significant reductions in PMR over the course of captivity, whereas PMR in aviary-housed birds were indistinguishable from their free-living counterparts. Testosterone treatment significantly increased leg muscle mass in caged birds, but had no effect on muscle mass in aviary-housed sparrows. We conclude that testosterone has no direct effect on sparrow metabolic rate or muscle mass, but may interact with cage conditions to produce indirect changes to these variables.

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The relationship between muscle strength and bone mineral density illustrates the positive effect of mechanical loading on bone. But local and systemic factors may affect both muscle and bone tissues. This study investigated the effects of long-term tennis playing on the relationship between lean tissue mass and bone mineral content in the forearms, taking the body dimensions into account. Fifty-two tennis players (age 24.2 +/- 5.8 yrs, 16.2 +/- 6.1 yrs of practice) were recruited. Lean tissue mass (LTM), bone area, bone mineral content (BMC), and bone mineral density were measured at the forearms from a DXA whole-body scan. Grip strength was assessed with a dynamometer. A marked side-to-side difference (p < 0.0001) was found in favor of the dominant forearm in all parameters. Bone area and BMC correlated with grip strength on both sides (r = 0.81 - 0.84, p < 0.0001). The correlations were still significant after adjusting for whole-body BMC body height, or forearm length. This result reinforced the putative role of the muscles in the mechanical loading on bones. In addition, forearm BMC adjusted to LTM or grip strength was higher on the dominant side, suggesting that tennis playing exerts a direct effect on bone.

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The benefit of impact-loading activity for bone strength depends on whether the additional bone mineral content (BMC) accrued at loaded sites is due to an increased bone size, volumetric bone mineral density (vBMD) or both. Using magnetic resonance imaging (MRI) and dual energy X-ray absorptiometry (DXA), the aim of this study was to characterize the geometric changes of the dominant radius in response to long-term tennis playing and to assess the influence of muscle forces on bone tissue by investigating the muscle–bone relationship. Twenty tennis players (10 men and 10 women, mean age: 23.1 ± 4.7 years, with 14.3 ± 3.4 years of playing) were recruited. The total bone volume, cortical volume, sub-cortical volume and muscle volume were measured at both distal radii by MRI. BMC was assessed by DXA and was divided by the total bone volume to derive vBMD. Grip strength was evaluated with a dynamometer. Significant side-to-side differences (P < 0.0001) were found in muscle volume (+9.7%), grip strength (+13.3%), BMC (+13.5%), total bone volume (+10.3%) and sub-cortical volume (+20.6%), but not in cortical volume (+2.6%, ns). The asymmetry in total bone volume explained 75% of the variance in BMC asymmetry (P < 0.0001). vBMD was slightly higher on the dominant side (+3.3%, P < 0.05). Grip strength and muscle volume correlated with all bone variables (except vBMD) on both sides (r = 0.48–0.86, P < 0.05–0.0001) but the asymmetries in muscle parameters did not correlate with those in bone parameters. After adjustment for muscle volume or grip strength, BMC was still greater on the dominant side. This study showed that the greater BMC induced by long-term tennis playing at the dominant radius was associated to a marked increase in bone size and a slight improvement in volumetric BMD, thereby improving bone strength. In addition to the muscle contractions, other mechanical stimuli seemed to exert a direct effect on bone tissue, contributing to the specific bone response to tennis playing.

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The function of avian ultraviolet (UV) vision is only just beginning to be understood. One plausible hypothesis is that UV vision enhances the foraging ability of birds. To test this, we carried out behavioural experiments using wild-caught blue tits foraging for cabbage moth and winter moth caterpillars on natural and artificial backgrounds. The light environment in our experiments was manipulated using either UV-blocking or UV-transmitting filters. We found that the blue tits tended to find the first prey item (out of four) more quickly when UV cues were present. This suggests that UV vision offers benefits to birds when searching for cryptic prey despite the prey and backgrounds reflecting relatively little UV Although there was no direct effect of UV on the time taken to find all four prey items in a trial, search performance in the absence of UV wavelengths tended to increase over the course of an experiment. This may reflect changes in the search tactics of the birds. To our knowledge, these are the first data to suggest that birds use UV cues to detect cryptic insect prey and have implications for our understanding of protective coloration.

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Sexual arousal is a complex and dynamic element of women’s sexuality. Accounts vary, however most multidimensional models highlight the cognitive, affective and physiological components of the female sexual arousal response. While literature examining the peripheral physiological changes that occur during female sexual arousal abounds, there has been a dearth of literature pertaining to the cognitive and affective components. Thus, while many authors have included cognitive and emotions as independent components of the female sexual arousal response, there has been little empirical research to validate this approach. The aim of the current thesis was to examine the cognitive and affective components of female sexual arousal in more depth, investigating the nature of the relationship between these components under various experimental conditions. In order to do so, two integrated studies were conducted, each highlighting the effects of either external or internal variables on women’s subjective sexual arousal, absorption, positive affect and negative affect. Study One was designed to evaluate women’s emotional and cognitive processing of two elements of erotic film – foreplay and erotic context. 60 women were asked to report their subjective sexual arousal, absorption, positive affect and negative affect in response to one of four erotic film excerpts. The erotic excerpts varied in accordance with the degree of foreplay (low vs. high) depicted and the context in which the sexual activities took place (novel vs. habitual context). Women in the study responded more favourably to the high foreplay erotic film excerpt, subsequently reporting higher degrees of subjective sexual arousal, absorption and positive affect. Women also responded favourably to the erotic excerpt filmed in a novel context, reporting greater subjective sexual arousal as a result. The environment in which the sexual encounters were filmed failed to have an effect however, on women’s absorption or their positive or negative affect. The results of Study One suggest that stimulus specific variables, such as the degree of foreplay depicted, have a significant influence on female cognitive and emotional processing of erotic film. The results also suggest that a relationship exists between absorption, subjective sexual arousal and positive affect, albeit a correlational one. Specifically, there was evidence of parallel processing during sexual arousal, as participant reported sexual arousal, absorption and positive affect all increased and decreased in unison. Based on the results it was suggested that future research attempt to experimentally manipulate one of these variables, to examine its direct effect on the remaining variable. Thus, Study Two aimed to examine the effects of absorption on women’s cognitive and emotional processing of erotica. Study Two manipulated absorption at two levels (high vs. low), examining the impact of these states on participants’ subsequent absorption, subjective sexual arousal and positive and negative affect. 62 women were asked to read one of two sets of test session instructions. The first, participant-oriented instruction set, instructed participants to immerse themselves in the erotic film excerpt, as if they were active participants in the sexual exchange. The second, spectator-oriented instruction set, directed participants to observe and evaluate the erotic film. These instructions were designed to elicit high and low degrees of absorption, respectively. The utility of this approach when manipulating female absorption, was demonstrated by self reported ratings of absorption, given at the conclusion of the film presentation. Participants were also asked to report their subjective sexual arousal and positive and negative affect at the conclusion of the erotic film presentation. The findings of this study suggest that the adoption of a participant-oriented (high absorption) perspective elicits more favourable responses from participants than a spectator-oriented (low absorption) perspective, with participants in the former experimental group reporting greater degrees of subjective sexual arousal and positive affect. Negative affect was equivalent across experimental conditions, with the participants reporting that they experienced little to no aversive feelings during either of the experimental conditions. The results suggest that the degree to which a women immerses and absorbs herself in a sexual stimulus has a significant impact in her subsequent cognitive and affective processing of that stimulus. More specifically, it appears that women respond more favourably when they are highly absorbed and immersed in a stimulus, reporting greater subjective sexual arousal and positive affect. Overall, the results of Studies One and Two highlight the dynamic and complex nature of female sexual arousal. It appears that women have definite cognitive and affective responses to sexual stimuli. The magnitude of these responses may be mediated by a number of factors however, including the intrinsic qualities of the stimulus and the degree to which the woman attends to the stimulus. Both these variables act to either enhance or inhibit the sexual arousal response. There results have important implications for current sexuality literature. While women’s cognitions and emotions in response to erotic film were generally highly correlated, in some instances they differed, warranting their inclusion as separate elements in models of female sexual arousal. Furthermore, it might be suggested that the inclusion of an additional variable – absorption – into current models of female sexual arousal would prove beneficial, aiding researchers to better understand and predict the arousal process. As such, recommendations are made for a revised model of female sexual arousal. In terms of future directions, the results of the present thesis have implications for the treatment of sexual dysfunctions, suggesting that clinicians need to understand the internal and external variables that might contribute to the aetiology and maintenance of their presenting problems.

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Information technology research over the past two decades suggests that the installation and use of computers fundamentally affects the structure and function of organisations and, m particular, the workers in these organizations. Following the release of the IBM Personal Computer in 1982, microcomputers have become an integral part of most work environments. The accounting services industry, in particular, has felt the impact of this ‘microcomputer revolution’. In Big Six accounting firms, there is almost one microcomputer for each professional accountant employed, Notwithstanding this, little research has been done on the effect of microcomputers on the work outcomes of professional accountants working in these firms. This study addresses this issue. It assesses, in an organisational setting, how accountant’ perceptions of ease of use and usefulness of microcomputers act on their computer anxieties, microcomputer attitudes and use to affect their job satisfaction and job performance. The research also examines how different types of human-computer interfaces affect the relationships between accountants' beliefs about microcomputer utility and ease of use, computer anxiety, microcomputer attitudes and microcomputer use. To attain this research objective, a conceptual model was first developed, The model indicates that work outcomes (job satisfaction and job performance) of professional accountants using microcomputers are influenced by users' perceptions of ease of use and usefulness of microcomputers via paths through (a) the level of computer anxiety experienced by users, (b) the general attitude of users toward using microcomputers, and (c) the extent to which microcomputers are used by individuals. Empirically testable propositions were derived from the model to test the postulated relationships between these constructs. The study also tested whether or not users of different human-computer interfaces reacted differently to the perceptions and anxieties they hold about microcomputers and their use in the workplace. It was argued that users of graphical interfaces, because of the characteristics of those interfaces, react differently to their perceptions and anxieties about microcomputers compared with users of command-line (or textual-based) interfaces. A passive-observational study in a field setting was used to test the model and the research propositions. Data was collected from 164 professional accountants working in a Big Six accounting firm in a metropolitan city in Australia. Structural equation modelling techniques were used to test the, hypothesised causal relationships between the components comprising the general research model. Path analysis and ordinary least squares regression was used to estimate the parameters of the model and analyse the data obtained. Multisample analysis (or stacked model analysis) using EQS was used to test the fit of the model to the data of the different human-computer interface groups and to estimate the parameters for the paths in those different groups. The results show that the research model is a good description of the data. The job satisfaction of professional accountants is directly affected by their attitude toward using microcomputers and by microcomputer use itself. However, job performance appears to be only directly affected by microcomputer attitudes. Microcomputer use does not directly affect job performance. Along with perceived ease of use and perceived usefulness, computer anxiety is shown to be an important determinant of attitudes toward using microcomputers - higher levels of computer anxiety negatively affect attitudes toward using microcomputers. Conversely, higher levels of perceived ease of use and perceived usefulness heighten individuals' positive attitudes toward using microcomputers. Perceived ease of use and perceived usefulness also indirectly affect microcomputer attitudes through their effect on computer anxiety. The results show that higher levels of perceived ease of use and perceived usefulness result in lower levels of computer anxiety. A surprising result from the study is that while perceived ease of use is shown to directly affect the level of microcomputer usage, perceived usefulness and attitude toward using microcomputers does not. The results of the multisample analysis confirm that the research model fits the stacked model and that the stacked model is a significantly better fit if specific parameters are allowed to vary between the two human-computer interface user groups. In general, these results confirm that an interaction exists between the type of human-computer interface (the variable providing the grouping) and the other variables in the model The results show a clear difference between the two groups in the way in which perceived ease of use and perceived usefulness affect microcomputer attitude. In the case of users of command-line interfaces, these variables appear to affect microcomputer attitude via an intervening variable, computer anxiety, whereas in the graphical interface user group the effect occurs directly. Related to this, the results show that perceived ease of use and perceived usefulness have a significant direct effect on computer anxiety in command-line interface users, but no effect at all for graphical interface users. Of the two exogenous variables only perceived ease of use, and that in the case of the command-line interface users, has a direct significant effect on extent of use of microcomputers. In summary, the research has contributed to the development of a theory of individual adjustment to information technology in the workplace. It identifies certain perceptions, anxieties and attitudes about microcomputers and shows how they may affect work outcomes such as job satisfaction and job performance. It also shows that microcomputer-interface types have a differential effect on some of the hypothesised relationships represented in the general model. Future replication studies could sample a broader cross-section of the microcomputer user community. Finally, the results should help Big Six accounting firms to maximise the benefits of microcomputer use by making them aware of how working with microcomputers affects job satisfaction and job performance.

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Information technology continues to play an increasingly significant role in the development of firms competing in the vast array of markets from those classified as global markets, such as the automotive industry, to the smaller nationally-based markets such as retailing. An objective of electronic commerce is to assist organisations to remain competitive and gain entry to markets which were previously unattainable. This study focuses on the organisational impact of one form of electronic commerce (electronic data interchange) on the component sector of the Australian automotive industry and examines the extent to which trading partner relationships have been affected. The research investigates the extent to which the integration of electronic data interchange (EDI) with an organisation’s internal application system may facilitate specific net benefits. The automotive industry became the first Australian industry to cooperatively adopt EDI. Research to date has not adequately examined the organisational impact of the nature and extent of net benefits gained from EDI adoption. To achieve the objective of assessing EDI net benefits, a conceptual model was developed. The model proposed that the level of EDI net benefits expected is influenced by the size of the organisation and the concentration of trade achieved within the industry via intervening links through (a) the level of senior management commitment and (b) the extent of system integration. Nine empirically testable research propositions are derived from the model, each testing the relationship between model constructs. Data was collected from 114 component suppliers to Ford Australia in 1992 and 1994 using a repeated cross-sectional longitudinal design. Structural equation modelling using partial least squares was adopted in the analysis of the data. A pure longitudinal model together with 12 case studies of selected component manufacturers supplemented the research design. The results of the research showed that the proposed conceptual model is a good description of the data. In particular, net benefits obtained from EDI adoption are directly determined by the size of the organisation, and the extent to which firms integrate EDI into their internal application systems. The level of net benefits is only indirectly influenced by the level of senior management commitment to the EDI project through (a) management commitment’s direct effect on integration, and (b) the direct effect the volume of trade a supplier achieves with the automotive industry on senior management commitment and system integration. The major benefits organisations experienced from EDI were enhanced productivity, clerical staff savings, improved data accuracy, enhanced customer service and reduced administration costs. The research showed that few suppliers gained inventory savings from EDI, a frequently claimed benefit from EDI adoption. Evidence of small improvements in product quality emerged from the results. In summary, this research attempts to make two primary contributions to knowledge, first in providing a method by which net benefits from electronic commerce can be measured within an industry adopting electronic trading, and second, by providing organisations with the knowledge of the specific net benefits organisations could expect from EDI adoption, together with the four major factors affecting these benefits. The research concludes with possible directions for future research, in particular an assessment of the impact of incorporating financial EDI into electronic trading.

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The potential effects of early environmental conditions on adult female mate choice have been largely neglected in studies of sexual selection. Our study tested whether developmental stress affects the mate choice behaviour of female zebra finches, Taeniopygia guttata, when choosing between potential mates. In an experiment manipulating developmental condition, female zebra finches were raised under nutritional stress or control conditions. In adulthood, female preferences were assessed using extensive four-stimulus mate choice trials. Nutritional stress affected growth rates during the period of stress, with experimentally stressed females lighter than controls. During mate choice trials stressed females were almost three times less active than controls and made fewer sampling visits to the stimulus males, although we found no evidence of a direct effect of developmental experience on which males were preferred. Thus, developmental experience had a clear effect on behavioural patterns in a mate choice context. To test whether this effect is specific to a mate choice context, we also investigated the effect of developmental stress on female activity rates in three social contexts: isolation, contact with a conspecific male (a potential mate) and contact with a conspecific female. Here, female activity did not differ between the experimental treatments in any of the social situations. Overall, our findings suggest that environmental conditions during early development can have long-term context-dependent consequences for adult female mate choice behaviour, mediated by changes in activity rates.

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Background: Much evidence has accumulated over the last three decades that low social support is related to both mental and physical health. Despite this large and convincing literature, reviewers have noted that there exists remarkably little evidence that social support can be increased by an appropriate intervention. This study reports on the development and evaluation of a new intervention for social support which takes account of the stress-buffering and direct effect models.

Method: Eighty-one individuals scoring low on social support were randomly allocated to the intervention or a waiting-list control condition. Treatment consisted of 10 weekly sessions administered in a group format, and 49 participants (nine males) completed assessments at the beginning and end of a 10-week period, and at 10-week follow-up (intervention condition only).

Results: The intervention proved to be successful at increasing functional support but not structural support. The intervention was also successful in increasing the social skill of self-disclosure, and decreasing depression. Gains made between pre- and post-treatment were maintained at 10-week follow-up.

Conclusions: Based on published analyses of the effects of social support on health, the results imply that the intervention would be useful for stress-buffering purposes, but not for the general health-promoting effects that are associated with good social integration.

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The late-2000s global financial crisis has wrought dramatic impacts on the construction industry. However, the issue of whether the crisis influenced the behaviours of the construction industry has not been addressed yet. This research presents an econometric approach to investigating the effects of the recent global financial crisis on construction labour productivity. By employing the error correction model and panel regression methods, the direct and indirect effects of the financial crisis on the changes in Australian construction labour productivity are explored at national and state levels. Neither the direct nor the indirect effects appear statistically significant. The results indicate that the direct effect of the financial crisis drives up construction labour productivity at the national level, while the indirect effect diminishes productivity. The effects of the financial crisis on the state construction labour productivity vary from state to state. The financial crisis influenced construction labour productivity directly and significantly in the northern and eastern regions, while the direct effects appear not significant in the other states and territories. The indirect effects of the financial crisis on productivity are statistically significant in three regions: the Australian Capital Territory, the Northern Territory and Western Australia. By comparison, the model with the financial effects fails to provide more accurate simulating results. As such, this research concludes that the influence of the late-2000s financial crisis on Australian national and state construction labour productivity is limited.

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Objectives We hypothesized that the psychosocial factors perceived stress and sense of personal control mediated the relationship between self-reported racism and experience of toothache. We hypothesized that social support moderated this relationship. Methods Data from 365 pregnant Aboriginal Australian women were used to evaluate experience of toothache, socio-demographic factors, psychosocial factors, general health, risk behaviors, and self-reported racism exposure. Hierarchical logistic regression models estimated odds ratios (ORs) and 95 percent confidence intervals (CIs) for experience of toothache. Perceived stress and sense of personal control were examined as mediators of the association between self-reported racism and experience of toothache. Social support was examined as a moderator. Results Self-reported racism persisted as a risk indicator for experience of toothache (OR 1.99, 95 percent CI 1.07-3.72) after controlling for age, level of education, and difficulty paying a $100 dental bill. The relationship between self-reported racism and experience of toothache was mediated by sense of control. The direct effect of self-reported racism on experience of toothache became only marginally significant, and the indirect effect was significant (β coefficient-=-0.04, bias-corrected 95 percent CI 0.004-0.105, 21.2 percent of effect mediated). Stress was insignificant as a mediator. Social support was insignificant as a moderator. Conclusions The findings indicate that high levels of self-reported racism were associated with experience of toothache and that sense of control, but not perceived stress, mediated the association between self-reported racism and experience of toothache among this sample of pregnant Aboriginal Australian women. Social support did not moderate the association between self-reported racism and experience of toothache.

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We review recent developments in the estimation of an optimal treatment strategy or regime from longitudinal data collected in an observational study. We also propose novel methods for using the data obtained from an observational database in one health-care system to determine the optimal treatment regime for biologically similar subjects in a second health-care system when, for cultural, logistical, or financial reasons, the two health-care systems differ (and will continue to differ) in the frequency of, and reasons for, both laboratory tests and physician visits. Finally, we propose a novel method for estimating the optimal timing of expensive and/or painful diagnostic or prognostic tests. Diagnostic or prognostic tests are only useful in so far as they help a physician to determine the optimal dosing strategy, by providing information on both the current health state and the prognosis of a patient because, in contrast to drug therapies, these tests have no direct causal effect on disease progression. Our new method explicitly incorporates this no direct effect restriction.

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The objective of the present study was to evaluate the effects of altered dietary n-3/n-6 LC-PUFA ratio, adaptation to diet over time, different water temperatures, and their interactions on nutrients and fatty acids digestibility in juvenile Atlantic salmon. Three experimental diets were formulated to be identical, with the only exception of the ratio of eicosapentaenoic acid (EPA, 20:5n-3) to arachidonic acid (ARA, 20:4n-6), and fed to triplicate groups of juvenile Atlantic salmon (Salmo salar) of 55. g initial body weight. Fish were reared in a fully controlled recirculating aquaculture system, fed to apparent satiety twice daily and kept at 10. °C and for an initial period of 100. days, and faeces were collected for digestibility estimation. Then, half of the fish of each experimental tank were moved to a separate system, where the water temperature was gradually increased up to 20. °C. Fish were maintained in the two systems for an additional period of 50. days, and faeces were collected for digestibility estimation from both groups of fish at the two water temperatures. This study concluded that dietary treatments and time had only minor effects, whereas environmental temperature resulted in modified digestibility values, with increased nutrient digestibility with increasing temperature. Varying EPA/ARA ratio in the diet had only minor direct effects on digestibility, with no direct effect on overall nutrients digestibility, and fundamentally only statistically significant effects in the fatty acid digestibility of EPA and ARA themselves. Because of current increasing pressure for more efficient fish oil replacement strategies, increasing interest in dietary ARA in aquafeed and increasing relevance and occurrence of sub-optimal rearing temperature in commercial aquaculture, this study can be considered to be important as it provided a series of fundamental information, which are envisaged to be useful towards addressing these constraints and possible nutritional remedial strategies.