Performance of intensively farmed Murray cod Maccullochella peelii peelii (Mitchell) fed newly formulated vs. currently used commercial diets, and a comparison of fillet composition of farmed and wild fish

Murray cod is a top-order carnivore with high culture potential. Currently, there are no commercial diets formulated specifically for Murray cod. In this study, results of two growth trials on Murray cod (80–83.5-g mean initial weight), conducted in commercial settings, using two laboratory-formulated diets (DU1 and DU2; 48.9% and 49.1% protein, and 16.9% and 16.1% lipid, respectively, on a dry matter basis), and two commercial diets, formulated for other species (salmon – CD/S and barramundi – CD/B) but used in Murray cod farming are presented. The two commercial diets had less protein (46.6% and 44.4%) but higher lipid (21.7% and 19.5%). The energy content of the feeds tested was similar (about 20–22 kJ g−1). The growth performance and feed utilization of Murray cod did not differ significantly amongst the diets, but the food conversion ratio and % protein efficiency ratio in fish fed the DU1 and DU2 diets were consistently better. There was significantly less carcass and muscle lipid deposition in fish fed with the latter diets. Of the fatty acids in muscle, the lowest amounts (in μg mg lipid−1) of n-3 (262.5±2.9), n-6 (39.8±0.9) and polyunsaturated fatty acid (PUFA) (302.3±3.8) were observed in fish fed CD/S, and the highest in fish fed DU2 and CD/B. Fatty acids 16:0 and 18:0, 18:1n-9 and 16:1n-7, and 22:6n-3, 20:5n-3, 22:5n-3 and 18:2n-6 were the dominant fatty acids amongst the saturates, monoenes and PUFA, respectively, and accounted for 80.8–88.7% of all identified fatty acids (23) in muscle of Murray cod. The study showed that Murray cod could be cultured successfully on a diet (DU2) containing 20% soybean meal without compromising growth and/or carcass quality. Differences in the proximate composition and fatty acid composition of muscle of wild and farmed Murray cod were observed, the most obvious being in the latter. Wild Murray cod had significantly less (P<0.05) saturates (192.6±1.84 vs. 266.3±3.51), monoenes (156.5±8.7 vs. 207.6±6.19), n-3 (145.2±5.24 vs. 261.8±3.2) but higher n-6 (144.3±2.73 vs. 48.3±1.38) in muscle (all values are in μg mg lipid−1) than in farmed fish. Wild fish also had a much lower n-3 to n-6 ratio (1.0±0.03 vs. 5.4±0.09).

Consumers' readiness to eat a plant-based diet

Objective: The aim of this study was to examine consumers' readiness to change to a plant-based diet. Design: Mail survey that included questions on readiness to change, eating habits and perceived benefits and barriers to the consumption of a plant-based diet. Setting: Victoria, Australia. Subjects: A total of 415 randomly selected adults. Results: In terms of their readiness to eat a plant-based diet, the majority (58%) of participants were in the precontemplation stage of change, while 14% were in contemplation/preparation, and 28% in action/maintenance. Those in the action/maintenance stage ate more fruit, vegetables, nuts, seeds, whole-meal bread, and cooked cereals than those in earlier stages. There were statistically significant differences in age and vegetarian status between the stages of change, but not for other demographic variables. There were strong differences across the stages of change with regard to perceived benefits and barriers to plant-based diets. For example, those in action/maintenance scored highest for benefit factors associated with well-being, weight, health, convenience and finances, whereas those in the precontemplation stage did not recognise such benefits. Conclusions: These findings can be utilised to help provide appropriate nutrition education and advertising, targeted at specific stages of change. For example, education about how it is possible to obtain iron and protein from a plant-based diet and on the benefits of change, in addition to tips on how to make a gradual, easy transition to a plant-based diet, could help progress precontemplators to later stages.

Australian sweet lupin flour addition reduces the glycaemic index of a white bread breakfast without affecting palatability in healthy human volunteers

The addition of some legume ingredients to bread has been associated with effects on glycaemic, insulinaemic and satiety responses that may be beneficial in controlling type 2 diabetes, cardiovascular disease and obesity. However, the effect of Australian sweet lupin (Lupinus angustifolius) flour (ASLF) is unknown. This investigation examined the effect of adding ASLF to standard white bread on post-meal glycaemic, insulinaemic and satiety responses and palatability in healthy subjects. Using a randomised, single-blind, cross-over design, 11 subjects consumed one breakfast of ASLF bread and two of standard white bread ≥ 7 days apart after fasting overnight. Each breakfast also included margarine, jam, and tea with milk and contained 50g available carbohydrate. On each test day, blood samples were taken after fasting, then several times over 2 hours post-prandially, and analysed for plasma glucose and serum insulin. Subjects rated breakfast palatability and perception of satiety, in the fasting state and over 3 hours post-prandially, after which food intake from an ad libitum buffet and for the rest of the day was recorded. Incremental areas under the curves for glucose, insulin and satiety, glycaemic index, insulinaemic index and satiety index were calculated. ASLF addition to the breakfast reduced its glycaemic index (mean ± SEM; ASLF bread breakfast = 74.0 ± 9.6. Standard white bread breakfast = 100, P=0.022), raised its insulinaemic index (ASLF bread breakfast = 127.7 ± 12.0. Standard white bread breakfast = 100, P=0.046), but did not affect palatability, satiety or food intake. ASLF addition resulted in a palatable breakfast; however, the potential benefits of the lowered glycaemic index may be eclipsed by the increased insulinaemic index.

In vitro carbohydrate digestibility of whole-chickpea and chickpea bread products

Pulses such as the chickpea are generally considered to be valuable dietary sources of slowly digestible starch, a form of starch that is considered beneficial to health since it results in relatively low post-meal blood glucose levels compared with more rapidly digested starch. The development of novel chickpea-based foods is necessary to help expand the worldwide consumption of the chickpea. However, the effect of different processing methods on the starch digestibility of chickpea-based foods has not been widely investigated. This study used an in vitro method simulating human carbohydrate digestion to determine levels of slowly digestible starch, rapidly digestible starch (RDS), resistant starch, total starch and rapidly available glucose (RAG) of: (i) whole-chickpea products (domestically boiled, commercially canned and commercially precooked/vacuum-packaged); and (ii) standard white bread, chickpea flour bread (25% replacement of wheat flour by chickpea flour) and extruded chickpea flour bread (25% replacement of wheat flour by extruded chickpea flour). The RAG levels were then used to predict the relative in vivo glycaemic indices of the products. The commercially precooked/vacuum-packaged whole chickpeas demonstrated higher levels of RDS than the commercially canned and domestically boiled products (P<0.05). In addition, the domestically boiled product had lower levels of RAG (g/100 g available carbohydrate) compared with the canned and precooked/vacuum-packaged products (P<0.05). There were no significant differences between any of the carbohydrate digestibility measures of the white bread, chickpea flour bread and extruded chickpea flour bread (P>0.05) and all bread products demonstrated far higher RAG (g/100 g available carbohydrate) values than the whole-chickpea products. The findings suggest that the commercially precooked/vacuum-packaged whole chickpeas and the canned product may have higher and less beneficial glycaemic indices than the domestically boiled chickpeas. It appears unlikely that the use of chickpea flour or extruded chickpea flour, at the incorporation rate investigated in this study, would modify the glycaemic index of bread. It is probable, however, that the chickpea bread products investigated would demonstrate higher and potentially less beneficial glycaemic indices than the whole-chickpea products.

Post-migration food habits of sub-Saharan migrants in Victoria: a cross-sectional study

Objective: (i) To describe sub-Saharan African (SSA) post-migration food habits and eating patterns; and (ii) to examine how the food habits of SSA households in Victoria reflect post-migration acculturation.
Design: A cross-sectional survey using a snowball sampling technique. Data on food habits and eating patterns were obtained using semi-structured, face-to-face interviews from November 2001 to April 2002.
Subjects: A total of 139 households of demographically diverse recent migrants from across sub-Saharan Africa.
Setting: Melbourne metropolitan and Melbourne fringes.
Analysis: Data were summarised using descriptive statistics.
Results: SSA migrants and refugees indicated dietary acculturation characterised by three processes: substitution, supplementation and modification of recipes. They experienced difficulty locating their traditional foods, in particular, African vegetables (34.2%), unprocessed maize meal (29.1%), camel milk (23.1%) and maize grain (13.7%). The new foods adopted since arrival were pizza, breakfast cereals and fast foods, but also included new fruits and vegetables. Takeaway food such as Pizza Hut or McDonalds featured prominently in the SSA post-migration diet. Reasons for eating out were favourite food (48.3%), routine family outing (38.3%), special occasion (33.3%) and no time to cook (25%). A significant change in meal pattern was the inclusion of breakfast, although 21% reported skipping breakfast.
Conclusion: Many of the observed dietary changes were not consistent with good health and may predispose this population to rapid weight gain and chronic disease. Rapid modernisation and the Anglo-Australian culture interact in a complex way with traditional eating and socialisation practices of SSA migrants. Understanding these forces can allow effective health promotion and community development strategies to be developed for the future health of SSA migrants and their communities.

Effects of dietary lipid sources on flavour volatile compounds of brown trout (Salmo trutta L.) fillet

The high cost and unpredictable availability of fish meal and fish oil (FO) forced feed mill companies to look for alternative ingredients for aquafeeds. In this study, the effects of alternative dietary lipid sources [FO as control, canola oil (CO), oleine oil (OO), poultry fat (PF) and pork lard (PL)] in trout feed on flavour volatile compounds occurring in brown trout (Salmo trutta L.) fillet were evaluated after 70 days of feeding (rearing temperature 14.6°C). Total amounts of volatile compounds identified were higher for fillets of fish fed diets containing only FO as lipid sources. Total amount of alcohols and aldehydes of the fillets were linearly directly related to the percentage content of polyunsaturated fatty acids (PUFA) n-3 of brown trout flesh. The use of alternative dietary lipid sources, modifying the fillet fatty acids composition, affect the total amount of volatile compounds and, changing the relative amount of each volatile compound, affect the flavour of the fish flesh.

Identifying opportunities and promoting discourse by modeling future development initiatives

Based on the development of case study research into the proposed rapid expansion of the Deakin University waterfront campus, this paper presents a computational approach to identifying and modelling future development initiatives within the urban context. The aim of the model is to augment cross-discipline discourse by generating an array of permutations that extend the range of potential design scenarios beyond the Iimits of an ad-hoc, piece-meal or discipline specific approach.

Growth performance, feed efficiency and fatty acid composition of juvenile Murray cod, Maccullochella peelii peelii, fed graded levels of canola and linseed oil

n two independent experiments, the effects of dietary inclusion of canola and linseed oil were evaluated in juvenile Murray cod (Maccullochella peelii peelii, Mitchell) over a 112-day period. In each experiment, fish received one of five semi-purified diets in which the dietary fish oil was replaced with canola oil (Experiment A) or linseed oil (Experiment B) in graded increments of 25% (0–100%). Murray cod receiving the graded canola and linseed oil diets ranged in final weight from 112.7 ± 7.6 to 73.8 ± 9.9 g and 93.9 ± 3.6 to 74.6 ± 2.2 g, respectively, and exhibited a negative trend in growth as the inclusion level increased. The fatty acid composition of the fillet and liver were modified extensively to reflect the fatty acid composition of the respective diets. Levels of oleic acid (18:1 n-9) and linoleic acid (18:2 n-6) increased with each level of canola oil inclusion while levels of α-linolenic acid (18:3 n-3) increased with each level of linseed oil inclusion. The concentration of n-3 highly unsaturated fatty acids in the fillet and liver decreased as the amount of vegetable oil in the diets increased. It is shown that the replacement of fish oil with vegetable oils in low fish meal diets for Murray cod is possible to a limited extent. Moreover, this study reaffirms the suggestion for the need to conduct ingredient substitution studies for longer periods and where possible to base the conclusions on regression analysis in addition to anova.

What help do young women want in their efforts to control their weight? Implications for program development

The aim of this study was to examine women's views on the usefulness of various types of information and practical sessions on weight control, their preferences for program delivery, and likelihood of participation. Cross-sectional survey of 462 women aged 18–33 years randomly selected from the community was conducted. We examined the perceived usefulness of various types of information and practical classes on weight control; preferred mode of delivery; willingness to participate. Among the women 82% were interested in trying to lose or control weight. Information on weight control was considered to be more useful than practical sessions. Information about meal planning, cooking and low-fat recipes and how to manage stress was considered most useful. Fifty-eight per cent of women reported they would prefer to participate in an individual face-to-face program delivered by a health professional. Thirty-one per cent of women reported it was very likely that they would participate in a program if it included the sort of things they considered useful and was offered in the way they preferred; a further 35% felt it 'likely'. It appears that health professional-delivered, individual, information-based programs appear most popular among this target group. Tailoring the content and delivery mode of weight management programs to young women's preferences may enhance program participation.

Which food-related behaviours are associated with healthier intakes of fruits and vegetables among women?

Objective To examine associations between shopping, food preparation, meal and eating behaviours and fruit and vegetable intake among women.
Design Cross-sectional survey.
Setting Community-based sample from metropolitan Melbourne, Australia.
Subjects A sample of 1136 women aged 18–65 years, randomly selected from the electoral roll.
Results Food-related behaviours reflecting organisation and forward-planning, as well as enjoyment of and high perceived value of meal shopping, preparation and consumption were associated with healthier intakes of fruits and vegetables. For example, women who more frequently planned meals before they went shopping, wrote a shopping list, enjoyed food shopping, planned in the morning what they will eat for dinner that night, planned what they will eat for lunch, reported they enjoy cooking, liked trying new recipes and who reported they sometimes prepare dishes ahead of time were more likely to consume two or more servings of vegetables daily. Conversely, women who frequently found cooking a chore, spent less than 15 minutes preparing dinner, decided on the night what they will eat for dinner, ate in a fast-food restaurant, ate takeaway meals from a fast-food restaurant, ate dinner and snacks while watching television and who frequently ate on the run were less likely to eat two or more servings of vegetables daily.
Conclusions Practical strategies based on these behavioural characteristics could be trialled in interventions aimed at promoting fruit and vegetable consumption among women.

Adolescent home food environments and socioeconomic position

Many adolescents have diets that are less than optimal, particularly adolescents of low socioeconomic position (SEP). The determinants of SEP differences in adolescent dietary intake are poorly understood. This study examined the home food environments of adolescents and specifically investigated whether low SEP adolescents have less supportive home local environments, fewer eating rules and poorer home availability of fruit and vegetables than adolescents of high SEP. A cross-sectional, self-reported survey was administered to 3,264 adolescents in years 7 and 9, from 37 secondary schools in Victoria, Australia. Adolescent perceptions of the home meal environment, eating rules and home food availability were described and compared across SEP, which was measured using maternal education. Maternal education was linked to various aspects of the home meal environment, as well as home food availability, but not to eating rules. Low SEP adolescents were more likely to report that they were always allowed to watch television during meal times, and that unhealthy foods were always or usually available at home. In contrast, high SEP adolescents were more likely to report that vegetables were always served at dinner, that the evening meal was never an unpleasant time and always or usually a time for family connectedness, and that fruit was always or usually available at home. This study highlights aspects of the home food environment that might explain SEP variation in adolescent diets. Feasible ways of increasing home availability of healthy foods, and encouraging home meal environments to be supportive of healthy eating should be explored, particularly in households of low SEP adolescents.

Snacking behaviours of adolescents and their association with skipping meals

Background: Snacking is likely to play an important role in the development of overweight and obesity, yet little is known about the contexts of snacking in adolescents or how snacking may influence other dietary habits, like meal skipping. This study examines the contexts in which adolescents snack and whether these contexts are associated with demographic characteristics of adolescents and with meal skipping.
Methods: A cross-sectional, self-reported online food habits survey was administered to 3,250 secondary students in years seven and nine. The students were drawn from 37 secondary schools in Victoria, Australia during 2004–2005. Frequencies of meal skipping, and snacking in eight contexts, were compared across gender, year level and region of residence. Logistic regressions were performed to examine associations between snacking contexts and meal skipping adjusting for gender and region.
Results: The most common contexts for snacking among adolescents were after school (4.6 times per week), while watching TV (3.5 times per week) and while hanging out with friends (2.4 times per week). Adolescents were least likely to snack all day long (0.8 times per week) or in the middle of the night (0.4 times per week). Snacking contexts were variously associated with gender, year level and region. In contrast, meal skipping was associated with gender and region of residence but not year level. Adolescents who reported more frequent snacking on the run, on the way to or from school, all day long, or in the middle of the night were more likely to skip meals.
Conclusion: These data suggest adolescents snack frequently, especially in their leisure time. In addition, adolescents who snack on the run, on the way to or from school, all day long or in the middle of the night are more likely to skip meals than are adolescents who don't snack at these times. Understanding the contexts in which adolescents snack, and their associations with skipping meals, may assist those involved in the promotion of healthy food habits among adolescents.

Pyruvate dehydrogenase activation and kinase expression in human skeletal muscle during fasting

Fasting forces adaptive changes in whole body and skeletal muscle metabolism that increase fat oxidation and decrease the oxidation of carbohydrate. We tested the hypothesis that 40 h of fasting would decrease pyruvate dehydrogenase (PDH) activity and increase PDH kinase (PDK) isoform mRNA expression in human skeletal muscle. The putative transcriptional activators of PDK isozymes, peroxisome proliferator-activated receptor-α (PPAR-α) protein, and forkhead homolog in rhabdomyosarcoma (FKHR) mRNA were also measured. Eleven healthy adults fasted after a standard meal (25% fat, 60% carbohydrate, 15% protein) with blood and skeletal muscle samples taken at 3, 15, and 40 h postprandial. Fasting increased plasma free fatty acid, glycerol, and β-hydroxybutyrate concentrations and decreased glucose and insulin concentrations. PDH activity decreased from 0.88 ± 0.11 mmol acetyl-CoA · min^-1 · kg wet muscle wt^-1 at 3 h to 0.62 ± 0.10 (P = not significant) and 0.39 ± 0.06 (P < 0.05) mmol · min^-1 · kg wet mass^-1 after 15 and 40 h of fasting. Although all four PDK isoforms were expressed in human skeletal muscle, PDK^-2 and -4 mRNA were the most abundant. PDK^-1 and ^-3 mRNA abundance was ~1 and 15% of the PDK^-2 and 4^- levels, respectively. The 40-h fast had no effect on PDK^-1, ^-2, and ^-3 mRNA expression. PDK-4 mRNA was significantly increased ~3-fold after 15 h and ~14-fold after 40 h of fasting. Skeletal muscle PPAR-α protein and FKHR mRNA abundance were unaffected by the fast. The results suggest that decreased PDH activation after 40 h of fasting may have been a function of the large increase in PDK-4 mRNA expression and possible subsequent increase in PDK protein and activity. The changes in PDK-4 expression and PDH activity did not coincide with increases in the transcriptional activators PPAR-α and FKHR.

Determination of astaxanthin steroisomers and colour attributes in flesh of rainbow trout (Oncorhynchus mykiss) as a tool to distinguish the dietary pigmentation source

The presence of carotenoids in animal tissue reflects their sources along the food chain. Astaxanthin, the main carotenoid used for salmonid pigmentation, is usually included in the feed as a synthetic product. However, other dietary sources of astaxanthin such as shrimp or krill wastes, algae meal or yeasts are also available on the market. Astaxanthin possesses two identical asymmetric atoms at C-3 and C-3' making possible three optical isomers with all-trans configuration of the chain: 3S,3'S, 3R,3'S, and 3R,3'R. The distribution of the isomers in natural astaxanthin differs from that of the synthetic product. This latter is a racemic mixture, with a typical ratio of 1:2:1 (3S,3'S:3R,3'S:3R,3'R), while astaxanthin from natural sources has a variable distribution of the isomers deriving from the different biological organism that synthesized it. The high-performance liquid chromatographic (HPLC) analysis of all-trans isomers of astaxanthin was performed in different pigment sources, such as red yeast Phaffia rhodozyma, alga meal Haematococcus pluvialis, krill meal and oil, and shrimp meal. With the aim to investigate astaxanthin isomer ratios in flesh of fish fed different carotenoid sources, three groups of rainbow trout were fed for 60 days diets containing astaxanthin from synthetic source, H. pluvialis algae meal and P. rhodozyma red yeast. Moreover, the distribution of optical isomers of astaxanthin in trout purchased on the Italian market was investigated. A characteristic distribution of astaxanthin stereoisomers was detected for each pigment sources and such distribution was reproduced in the flesh of trout fed with that source. Colour values measured in different sites of fillet of rainbow trout fed with different pigment sources showed no significant differences. Similarly, different sources of pigment (natural or synthetic) produced colour values of fresh fillet with no relevant or significant differences. The coefficient of distance computed amongst the feed ingredient and the trout fillet astaxanthin stereoisomers was a useful tool to identify the origin of the pigment used on farm.

Effect of dietary modificatio of muscle long-chainN-3 fatty acid on plasma insulin and lipid metabolite, carcass traits, and fat deposition in lambs

In a previous study we showed that feeding fish meal significantly increased muscle long chain n-3 fatty acids (FA) and hot carcass weight. In this study we compared the effect of fish meal and fish oil on increasing muscle long-chain FA. We also investigated whether the increase in carcass weight was due to the effect of dietary enrichment of muscle long-chain n-3 FA on muscle membrane phospholipids and(or) to rumen by-pass protein provided by fish meal. Forty crossbred ([Merino x Border Leicester] x Poll Dorset) wether lambs between 26 and 33 kg BW were randomly assigned to one of five treatments: 1) basal diet of oaten:lucerne chaff (Basal); 2) Basal + fish meal (9% DM) = FM; 3) Basal + fish oil (1.5% DM) with protected sunflower meal (9% DM ) = FOSMP; 4) Basal + fish oil (1.5% DM) = FO; or 5) Basal + protected sunflower meal (10.5% DM) = SMP. Daily intake of ME (9.60 - 10.5 MJ ME/d) and CP (150 to 168 g/d) in all treatments was kept similar by varying the ratio of oaten:lucerne chaff and by feeding the animals at 90% ad libitum intake. Blood samples were collected at the start of the experiment and on the day (d 42) prior to slaughter. Lambs were then slaughtered at a commercial abattoir. At 24 h postmortem carcass traits were measured and longis-simus thoracis muscle taken for analysis of FA of phospholipid and triglyceride fractions. Lambs fed FO and FOSMP showed a marked increase in muscle longchain n-3 FA (P < 0.001) and a reduction in magnitude of the rise in insulin concentration (P < 0.001) after feeding compared with lambs fed Basal and SMP diets. Lambs in FM had a moderate increase (P < 0.001) in muscle long-chain n-3 FA content. Compared with Basal diet, both plasma total cholesterol (P < 0.02) and high-density lipoprotein cholesterol (P < 0.001) levels were greater in SMP and less in FO and FOSMP treat- ments. The i.m. fat content was reduced (P < 0.05) in FM and FO treatments, but carcass weight was increased only with fish meal (P < 0.03). Adding SMP to FO produced muscle with an intermediate level of i.m. fat, whereas muscle long-chain n-3 FA, i.m. fat, and insulin concentration were unchanged with SMP treatment. These results indicate that an increase in carcass weight in FM may be due to the supply of ruminally undegraded protein. They also suggest that fish oil along with fish meal can increase long-chain n-3 FA content in phospholipid of muscle membrane. This may be associated with reduced i.m. fat content and altered insulin action and lipoprotein metabolism.