Assessment of oxidative damage to DNA, transcriptional expression of key genes, lipid peroxidation and histopathological changes in carp Cyprinus carpio L. following exposure to chronic hypoxic and subsequent recovery in normoxic conditions

In fish, a complex set of mechanisms deal with environmental stresses including hypoxia. In order to probe the hypothesis that hypoxia-induced stress could be manifested in varieties of pathways, a model species, mirror carp (Cyprinus carpio), were chronically exposed to hypoxic condition (dissolved oxygen level: 1.80 ± 0.6 mg/l) for 21 days and subsequently allowed to recover under normoxic condition (dissolved oxygen level: 8.2 ± 0.5 mg/l) for 7 days. At the end of these exposure periods, an integrated approach was applied to evaluate several endpoints at different levels of biological organisation. These included determination of (i) oxidative damage to DNA in erythrocytes (using modified comet assay), (ii) lipid peroxidation in liver samples by measuring the malondialdehyde production using the 2-thiobarbituric acid [i.e. thiobarbituric acid reactive substances (TBARS) assay] and (iii) histopathological changes in gills. In addition, transcriptional expression of hypoxia-inducible factor 1 α (HIF-1α) and genes involved in the repair of oxidative damage to DNA (i.e. ogg1) and base excision repair (i.e. xrcc1) using reverse transcription polymerase chain reaction in liver samples were also determined. The results suggested significantly enhanced expression of these genes in response to hypoxia compared to concurrent normoxic controls. While the expression of HIF-1α reverted to control values within 7 days exposure to normoxic condition (P < 0.05), the transcriptional expression of the two genes involved in DNA repair process remained significantly high under the recovery period, which complemented the induction of oxidative damage to DNA. Hypoxic groups showed significantly increased values for TBARS level (~2-fold) and histopathological changes in gill tissues compared to both normoxic and recovery groups. Overall, oxidative damage to DNA determined by modified comet assay reflected the observed biological responses in other tissues of the fish. Along with other parameters, this integrated experimental design further strengthens the applications of the comet assay as an important technique to assess stress-induced DNA damage in ecotoxicological studies.

Growth, Oxygen Consumption, and Behavioral Responses of Danio rerio to Variation in Dietary Protein and Lipid Levels

In recent years, there has been increasing interest in the welfare of ornamental fish. Diet can significantly impact the welfare of fish, which can manifest as changes in the fish's physical health and behavior. The zebrafish, Danio rerio, is a popular ornamental species; however, little is known about their nutritional requirements with possible implications for their welfare. Here, we investigated the effect of diets with increasing crude protein (iso-caloric diets) and lipid (iso-nitrogenous diets) on the growth performance, oxygen consumption, and behavior of zebrafish. We found no significant effects of crude protein (32%-75%) or lipid (8%-16%) on the specific growth rate or oxygen consumption of fish fed 5% of their body mass (BM)/day, although the highest crude protein and lipid diet resulted in an increase in condition factor. Furthermore, the crude protein diets did not affect zebrafish behavior when fed a 2% BM ration, once a day. This study has shown that a diet with 32% crude protein and a diet with 8% crude lipid, when fed at a 5% BM ration, were sufficient to meet the growth requirements of our zebrafish. These diets supported the fish's physical health and thus benefited their welfare.

Analgesia dose prescribing and estimated glomerular filtration rate decline: a general practice database linkage cohort study

OBJECTIVE

We aimed to quantify the short-term effect of non-steroidal anti-inflammatory drugs (NSAIDs), aspirin and paracetamol analgesia dose prescribing on estimated glomerular filtration rate (eGFR) decline in the general practice population.

DESIGN

A population-based longitudinal clinical data linkage cohort study.

SETTING

Two large general practices in North Staffordshire, UK.

PARTICIPANTS

Patients aged 40 years and over with ≥2 eGFR measurements spaced ≥90 days apart between 1 January 2009 and 31 December 2010 were selected.

EXPOSURE

Using WHO Defined Daily Dose standardised cumulative analgesia prescribing, patients were categorised into non-user, normal and high-dose groups.

OUTCOME MEASURE

The primary outcome was defined as a >5 mL/min/1.73 m(2)/year eGFR decrease between the first and last eGFR. Logistic regression analyses were used to estimate risk, adjusting for sociodemographics, comorbidity, baseline chronic kidney disease (CKD) status, renin-angiotensin-system inhibitors and other analgesia prescribing.

RESULTS

There were 4145 patients (mean age 66 years, 55% female) with an analgesia prescribing prevalence of 17.2% for NSAIDs, 39% for aspirin and 22% for paracetamol and stage 3-5 CKD prevalence was 16.1% (n=667). Normal or high-dose NSAID and paracetamol prescribing was not significantly associated with eGFR decline. High-dose aspirin prescribing was associated with a reduced risk of eGFR decline in patients with a baseline (first) eGFR ≥60 mL/min/1.73 m(2); OR=0.52 (95% CI 0.35 to 0.77).

CONCLUSIONS

NSAID, aspirin and paracetamol prescribing over 2 years did not significantly affect eGFR decline with a reduced risk of eGFR decline in high-dose aspirin users with well-preserved renal function. However, the long-term effects of analgesia use on eGFR decline remain to be determined.

Heart failure and chronic obstructive pulmonary disease multimorbidity at hospital discharge transition: a study of patient and carer experience

BACKGROUND

Care for patients with multimorbidity represents a major challenge not only for patients and carers but to health-care systems. Hospital discharge transition is a critical point at which challenges for multimorbidity may amplify.

OBJECTIVES

The main objective of the study was to explore the experiences of heart failure (HF) and chronic obstructive pulmonary disease (COPD) multimorbid patients and their carers on hospital discharge. Secondary objectives included identification of gaps in the health care of multimorbidity and optimal solutions from patients and carers' perspectives.

DESIGN

Mixed methods were applied to collect data using patient self-completion questionnaire from an adapted version of the American Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey and in-depth interviews.

SETTING

Participants were recruited from two cardiology and respiratory wards at a large regional hospital in England, and all had a multimorbidity diagnosis of COPD and HF.

RESULTS AND CONCLUSIONS

Findings revealed that patients experienced difficulties in their communication with health-care professionals and there were specific challenges with information about medication. Qualitative descriptions revealed that experiences fell into two main categories: (i) information transfer to patients with multimorbidity in terms of issues with medication and clarity of information on diagnosis and (ii) communication and continuity of care after discharge. Respondents highlighted gaps in the management of patients with multimorbidity of HF and COPD at the critical time of care transition. They suggested the need for a comprehensive, coordinated and integrated approach to incorporate patients, carers and staff preferences for treatment on discharge from hospital.

Dietary synbiotic application modulates Atlantic salmon (Salmo salar) intestinal microbial communities and intestinal immunity

A feeding trial was conducted to determine the effect of dietary administration of Pediococcus acidilactici MA18/5M and short chain fructooligosaccharides (scFOS) on Atlantic salmon (Salmo salar L.) intestinal health. Salmon (initial average weight 250 g) were allocated into triplicate sea pens and were fed either a control diet (commercial diet: 45% protein, 20% lipid) or a synbiotic treatment diet (control diet + P. acidilactici at 3.5 g kg(-1) and 7 g kg(-1) scFOS) for 63 days. At the end of this period, fish were sampled for intestinal microbiology, intestinal histology and the expression of selected immune-related genes (IL1β, TNFα, IL8, TLR3 and MX-1) in the intestine. Compared to the control fish, the total bacterial levels were significantly lower in the anterior mucosa, posterior mucosa and posterior digesta of the synbiotic fed fish. qPCR revealed good recovery (log 6 bacteria g(-1)) of the probiotic in the intestinal digesta of the synbiotic fed fish and PCR-DGGE revealed that the number of OTUs, as well as the microbial community diversity and richness were significantly higher in the anterior digesta of the synbiotic fed fish than the control. Compared to the control fed fish, the mucosal fold (villi) length and the infiltration of epithelial leucocytes were significantly higher in the anterior and posterior intestine, respectively, in the synbiotic group. Real-time PCR demonstrated that all of the genes investigated were significantly up-regulated in the anterior and posterior intestine of the synbiotic fed salmon, compared to the control group. At the systemic level, serum lysozyme activity was significantly higher in the synbiotic fed fish and growth performance, feed utilisation and biometric measurements (condition factor, gutted weight and gut loss) were not affected. Together these results suggest that the synbiotic modulation of the gut microbiota has a protective action on the intestinal mucosal cells, improving morphology and stimulating the innate immune response without negatively affecting growth performance or feed utilization of farmed Atlantic salmon.

Longitudinal study of small solute transport and peritoneal protein clearance in peritoneal dialysis patients

BACKGROUND AND OBJECTIVES

Peritoneal protein clearance (Pcl) is determined by both effective (small pores) membrane area and relative capillary leakiness (large pores). It is not known how these two components change with duration of peritoneal dialysis (PD) in the context of progressive membrane injury and differential attrition of patients with higher Pcl, which has been associated with increased mortality risk in several studies.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients treated continuously from 2000 to 2011 for a minimum of 4 years were selected from the longitudinal prospective Stoke PD Study. Pcl, membrane area (peritoneal solute transport rate [PSTR]), dialysis prescription, and residual renal function were measured every 6 months, along with comorbidity and peritonitis events. Multilevel multivariate analysis was used to determine associations with Pcl over time, taking into account within-subject correlations.

RESULTS

From 280 incident patients, 335 datasets were analyzed from 49 patients receiving treatment for 4 years. Pcl correlated with PSTR at baseline (R=0.61; P<0.01), but over time there was progressive uncoupling of this relationship (year 4, R=0.28; P=0.05) with increasing PSTR (0.66-0.74; P<0.01) and stable Pcl (78.4-81.9 ml/d; P=0.7). Multivariate analysis found that age, PSTR, daily ultrafiltration, and sodium removal were significant predictors of Pcl when adjusted for sex, comorbidity, glucose exposure, and residual renal function. Peritonitis was associated with increased PSTR but a similar pattern of uncoupling.

CONCLUSION

There is a progressive dissociation of the small- and large-pore pathways with time on PD, which would be in keeping with a switch from local inflammation early on to progressive fibrosis, combined with increased vascular surface area. Measuring longitudinal changes in Pcl may complement membrane function tests used to monitor progressive injury.

Probiotic Pediococcus acidilactici modulates both localised intestinal- and peripheral-immunity in tilapia (Oreochromis niloticus)

The application of probiotics in aquaculture has received concerted research efforts but the localised intestinal immunological response of fish to probiotic bacteria is poorly understood. Therefore, a study was conducted to evaluate the probiotic effect of Pediococcus acidilactici on Nile tilapia (Oreochromis niloticus) with specific emphasis on intestinal health and probiotic levels as well as system level responses such as growth performance, feed utilization and haemato-immunological parameters under non-challenged conditions. Fish (9.19 ± 0.04 g) were fed either a control diet or a P. acidilactici supplemented diet (at 2.81 × 10(6) CFU g(-)(1)) for six weeks. At the end of the study the probiotic was observed to populate the intestine, accounting for ca. 3% (1.59 × 10(5) CFU g(-)(1)) of the cultivable intestinal bacterial load. Real-time PCR indicated that the probiotic treatment may potentiate the immune-responsiveness of the intestine as up-regulation of the gene expression of the pro-inflammatory cytokine TNFα was observed in the probiotic fed fish (P < 0.05). Light microscopy observations revealed elevated intraepithelial leucocyte (IEL) levels in the intestine of P. acidilactici fed tilapia after six weeks (P < 0.05) of feeding and a trend towards elevated goblet cells was also observed after six weeks feeding (P = 0.08). Concomitantly at week six, along with elevated IELs and elevated TNFα mRNA levels in the intestine, an increased abundance of circulating neutrophils and monocytes were observed in fish fed the probiotic supplemented diet (P < 0.05). This haemopoietic expansion of innate immune cells could be reflective of an elevated state of immuno-readiness. Together these results suggest that the probiotic has a protective action on the intestinal mucosal cells, stimulating the innate immune response after feeding for a period of six weeks. These immunological modulations did not impair growth performance or the remaining haematological and zootechnical parameters compared to the control group (P > 0.05).

Crystalloid or colloid for goal-directed fluid therapy in colorectal surgery

BACKGROUND

Goal-directed fluid therapy has been shown to improve outcomes after colorectal surgery, but the optimal type of i.v. fluid to use is yet to be established. Theoretical advantages of using hydroxyethyl starch (HES) for goal-directed therapy include a reduction in the total volume of fluid required, resulting in less tissue oedema. Recent work has demonstrated that new generations of HES have a good safety profile, but their routine use in the perioperative setting has not been demonstrated to confer outcome benefit.

METHODS

We randomly assigned 202 medium to high-risk patients undergoing elective colorectal surgery to receive either balanced 6% HES (130/0.4, Volulyte) or balanced crystalloid (Hartmann's solution) as haemodynamic optimization fluid. The primary outcome measure was the incidence of gastrointestinal (GI) morbidity on postoperative day 5. Secondary outcome measures included the incidence of postoperative complications, hospital length of stay, and the effect of trial fluids on coagulation and inflammation.

RESULTS

No difference was seen in the number of patients who suffered GI morbidity on postoperative day 5 [30% in the HES group vs 32% in the crystalloid group; adjusted odds ratio=0.96 (0.52-1.77)]. Subjects in the crystalloid group received more fluid [median (inter-quartile ranges) 3175 (2000-3700) vs 1875 (1500-3000) ml, P<0.001] and had a higher 24 h fluid balance [+4226 (3251-5779) vs +3610 (2443-4519) ml, P<0.001]. No difference in the incidence of postoperative complications was seen between the groups.

CONCLUSIONS

Goal-directed fluid therapy is possible with either crystalloid or HES. There is no evidence of a benefit in using HES over crystalloid, despite its use resulting in a lower 24 h fluid balance.

Habitat filtering across tree life stages in tropical forest communities

Tropical tree communities are shaped by local-scale habitat heterogeneity in the form of topographic and edaphic variation, but the life-history stage at which habitat associations develop remains poorly understood. This is due, in part, to the fact that previous studies have not accounted for the widely disparate sample sizes (number of stems) that result when trees are divided into size classes. We demonstrate that the observed habitat structuring of a community is directly related to the number of individuals in the community. We then compare the relative importance of habitat heterogeneity to tree community structure for saplings, juveniles and adult trees within seven large (24-50 ha) tropical forest dynamics plots while controlling for sample size. Changes in habitat structuring through tree life stages were small and inconsistent among life stages and study sites. Where found, these differences were an order of magnitude smaller than the findings of previous studies that did not control for sample size. Moreover, community structure and composition were very similar among tree sub-communities of different life stages. We conclude that the structure of these tropical tree communities is established by the time trees are large enough to be included in the census (1 cm diameter at breast height), which indicates that habitat filtering occurs during earlier life stages.

Independent effects of systemic and peritoneal inflammation on peritoneal dialysis survival

Systemic inflammation, as evidenced by elevated inflammatory cytokines, is a feature of advanced renal failure and predicts worse survival. Dialysate IL-6 concentrations associate with variability in peritoneal small solute transport rate (PSTR), which has also been linked to patient survival. Here, we determined the link between systemic and intraperitoneal inflammation with regards to peritoneal membrane function and patient survival as part of the Global Fluid Study, a multinational, multicenter, prospective, combined incident and prevalent cohort study (n=959 patients) with up to 8 years of follow-up. Data collected included patient demographic characteristics, comorbidity, modality, dialysis prescription, and peritoneal membrane function. Dialysate and plasma cytokines were measured by electrochemiluminescence. A total of 426 survival endpoints occurred in 559 incident and 358 prevalent patients from 10 centers in Korea, Canada, and the United Kingdom. On patient entry to the study, systemic and intraperitoneal cytokine networks were dissociated, with evidence of local cytokine production within the peritoneum. After adjustment for multiple covariates, systemic inflammation was associated with age and comorbidity and independently predicted patient survival in both incident and prevalent cohorts. In contrast, intraperitoneal inflammation was the most important determinant of PSTR but did not affect survival. In prevalent patients, the relationship between local inflammation and membrane function persisted but did not account for an increased mortality associated with faster PSTR. These data suggest that systemic and local intraperitoneal inflammation reflect distinct processes and consequences in patients treated with peritoneal dialysis, so their prevention may require different therapeutic approaches; the significance of intraperitoneal inflammation requires further elucidation.

Effects of a dietary β-(1,3)(1,6)-D-glucan supplementation on intestinal microbial communities and intestinal ultrastructure of mirror carp (Cyprinus carpio L.)

AIM

To assess the effects of dietary Saccharomyces cerevisiae β-(1,3)(1,6)-D-glucan supplementation (MacroGard(®)) on mirror carp (Cyprinus carpio L.) intestinal microbiota and ultrastructure of the enterocyte apical brush border.

METHODS AND RESULTS

Carp were fed either a control diet or diets supplemented with 0.1, 1 or 2% w/w MacroGard(®). Culture-dependent microbiology revealed that aerobic heterotrophic bacterial levels were unaffected by dietary MacroGard(®) after 2 and 4 weeks. No effects were observed on the allochthonous lactic acid bacteria (LAB) populations at either time point; however, reduced autochthonous LAB populations were observed at week 4. PCR-DGGE confirmed these findings through a reduction in the abundance of autochthonous Lactococcus sp. and Vagococcus sp. in MacroGard(®)--fed fish compared with the control-fed fish. Overall, sequence analysis detected microbiota belonging to the phyla Proteobacteria, Firmicutes, Fusobacteria and unidentified uncultured bacteria. DGGE analyses also revealed that dietary MacroGard(®) reduced the number of observed taxonomical units (OTUs) and the species richness of the allochthonous microbiota after 2 weeks, but not after 4 weeks. In contrast, dietary MacroGard(®) reduced the number of OTUs, the species richness and diversity of the autochthonous microbiota after 2 weeks, and those parameters remained reduced after 4 weeks. Transmission electron microscopy revealed that intestinal microvilli length and density were significantly increased after 4 weeks in fish fed diets supplemented with 1% MacroGard(®).

CONCLUSIONS

This study indicates that dietary MacroGard(®) supplementation modulates intestinal microbial communities of mirror carp and influences the morphology of the apical brush border.

SIGNIFICANCE AND IMPACT OF THE STUDY

To the authors' knowledge, this is the first study to investigate the effects of β-(1,3)(1,6)-D-glucans on fish gut microbial communities, using culture-independent methods, and the ultrastructure of the apical brush border of the enterocytes in fish. This prebiotic-type effect may help to explain the mechanisms in which β-glucans provide benefits when fed to fish.

Comparison of stroke volume and fluid responsiveness measurements in commonly used technologies for goal-directed therapy

STUDY OBJECTIVE

To compare stroke volume (SV) and preload responsiveness measurements from different technologies with the esophageal Doppler monitor (EDM).

DESIGN

Prospective measurement study.

SETTING

Operating room.

PATIENTS

20 ASA physical status 3 patients undergoing vascular, major urological, and bariatric surgery.

INTERVENTIONS

Subjects received fluids using a standard Doppler protocol of 250 mL of colloid administered until SV no longer increased by >10%, and again when the measured SV decreased by 10%.

MEASUREMENTS

Simultaneous readings of SV, stroke volume variation (SVV) and pulse pressure variation (PPV) from the LiDCOrapid, and SVV from the FloTrac/Vigileo were compared with EDM measurements. The pleth variability index (PVI) also was recorded.

MAIN RESULTS

No correlation was seen in percentage SV change as measured by either the LiDCOrapid (r=0.05, P=0.616) or FloTrac (r=0.09, P= 0.363) systems compared with the EDM. Correlation was present between the LiDCOrapid and FloTrac (r=0.515, P<0.0001). Percentage error compared with the EDM was 81% for the FloTrac and 90% for the LiDCOrapid. SVV as measured by LiDCOrapid differed for fluid responders and nonresponders (10% vs 7%; P=0.021). Receiver operator curve analysis to predict a 10% increase in SV from the measured variables showed an area under the curve of 0.57 (95% CI 0.43-0.72) for SVV(FloTrac), 0.64 (95% CI 0.52-0.78) for SVV(LiDCO), 0.61 (95% CI 0.46 -0.76) for PPV, and 0.59 (95% CI 0.46 -0.71) for PVI.

CONCLUSIONS

Stroke volume as measured by the FloTrac and LiDCOrapid systems does not correlate with the esphageal Doppler, has poor concordance, and a clinically unacceptable percentage error. The predictive value of the fluid responsiveness parameters is low, with only SVV measured by the LiDCOrapid having clinical utility.

Non-steroidal anti-inflammatory drugs and chronic kidney disease progression: a systematic review

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely regarded as one risk factor, which influences chronic kidney disease (CKD) progression. However, previous literature reviews have not quantified the risk in moderate to severe CKD patients.

OBJECTIVE

To estimate the strength of association between chronic NSAID use and CKD progression.

METHODS

We conducted a systematic review and meta-analysis of observational general practice or population studies featuring patients aged 45 years and over. The electronic databases searched were MEDLINE, EMBASE, Cochrane, AMED, BNI and CINAHL until September 2011 without date or language restrictions. Searches included the reference lists of relevant identified studies, WEB of KNOWLEDGE, openSIGLE, specific journals, the British Library and expert networks. For relevant studies, random effects meta-analysis was used to estimate the association between NSAID use and accelerated CKD progression (estimated glomerular filtration rate decline ≥ 15 ml/min/1.73 m2).

RESULTS

From a possible 768 articles, after screening and selection, seven studies were identified (5 cohort, 1 case-control and 1 cross-sectional) and three were included in the meta-analysis. Regular-dose NSAID use did not significantly affect the risk of accelerated CKD progression; pooled odds ratio (OR) = 0.96 (95%CI: 0.86-1.07), but high-dose NSAID use significantly increased the risk of accelerated CKD progression; pooled OR = 1.26 (95%CI: 1.06-1.50).

CONCLUSIONS

The avoidance of NSAIDs in the medium term is unnecessary in patients with moderate to severe CKD, if not otherwise contraindicated. As the definition of high-dose of NSAID use remains unclear, the lowest effective dose of NSAIDs should be prescribed where indicated.

Peritoneal dialysis--current status and future challenges

Peritoneal dialysis is now a well established, mature treatment modality for advanced chronic kidney disease. The medium term (at least 5 year) survival of patients on peritoneal dialysis is currently equivalent to that of those on haemodialysis, and is particularly good in patients who are new to renal replacement therapy and have less comorbidity. Nevertheless the modality needs to keep pace with the constantly evolving challenges associated with the provision and delivery of health care. These challenges, which are gradually converging at a global level, include ageing of the population, multimorbidity of patients, containment of cost, increasing self care and environmental issues. In this context, peritoneal dialysis faces particular challenges that include multiple barriers to the therapy and unsatisfactory and poorly defined technique survival as well as limitations relating to intrinsic aspects of the therapy, such as peritoneal membrane longevity and hypoalbuminaemia. To move the therapy forward and favourably influence health-care policy, the peritoneal dialysis community needs to integrate their research effort more effectively by undertaking clinically meaningful studies-with a strong focus on technique survival--that are supported by multidisciplinary expertise in patient-centred outcomes, study design and analysis.

Effects of dietary β-(1,3)(1,6)-D-glucan supplementation on growth performance, intestinal morphology and haemato-immunological profile of mirror carp (Cyprinus carpio L.)

In recent years, aquaculture research has focused on probiotics, prebiotics, and β-glucans, in order to improve health status and growth performance. Information regarding the effects of β-glucan on growth performance and intestinal immunity of mirror carp (Cyprinus carpio L.) is scarce. An experiment was therefore conducted to investigate the effects of a yeast β-glucan preparation (MacroGard(®) ) on growth performance, intestinal morphology and haemato-immunological indices of mirror carp. Carp (initial weight 11.1 ± 0.0 g) were fed highly purified diets supplemented with 0% (control), 0.1%, 1% or 2% MacroGard(®) for 8 weeks. Fish fed diets containing 1% and 2% MacroGard(®) showed significant improvements in weight gain, specific growth rate and feed conversion ratio compared to fish fed both the control and the 0.1% MacroGard(®) containing diet. Histological appraisal of the intestine showed a significantly higher infiltration of leucocytes into the epithelial layer of fish fed diets supplemented with 1% and 2% MacroGard(®) in the anterior intestine compared to fish fed the control and 0.1% MacroGard(®) diet. This effect was not observed in the posterior intestine. There were no significant differences in the intestinal absorptive surface area and number of goblet cells in either intestinal region. At the end of the experiment, the haematological status of the fish was examined. Compared to control fed fish, the haematocrit value was significantly elevated in fish fed the 2% MacroGard(®) diet. Furthermore, the blood monocyte fraction was significantly higher in fish fed the 1% and 2% MacroGard(®) diets. No significant changes were observed in the other blood parameters assessed. The present study shows that high dietary β-glucan inclusion increases growth performance without detrimental effects on the health indicators assessed. Increased intraepithelial leucocytes in the anterior intestine may indicate a localized immune response; no detrimental effects on intestinal morphology were observed.