Fish oil replacement in finfish nutrition

Unsustainable fishing practices have placed a heavy emphasis on aquaculture to meet the global shortfalls in the supply of fish and seafood, which are commonly accepted as the primary source of health-promoting essential omega-3 (n-3 highly unsaturated fatty acids). However, dietary fish oil is required for the production of omega-3-rich farmed fish and this commodity, in a vicious circle, is at present derived solely from wild fisheries. Decreasing global availability coupled with the highly variable price of this resource has forced the aquaculture industry to investigate the possibilities of alternative dietary lipid sources. This review attempts to compile all principal information available regarding the effects of fish oil replacement for the diets of farmed finfish, analysing the findings using a comparative approach among different cultured fish species. The review initially focuses on the present situation with regard to the production, availability and main nutritional characteristics of fish oil and the principal alternative lipid sources (such as vegetable oils and animal fats). Following this, the effects of fish oil replacement in finfish nutrition on feed quality, fish performance, feed efficiency, fish lipid metabolism, final eating quality and related economic aspects are presented and discussed.

Conventions of pictorialism (iconic imagery, perceived space and the picture plane) deconstructed and reconstructed as alternative models of perception, embodied in paintings and drawings

This thesis is concerned with conventions of pictorialism, viz. the surface of an artwork or the plane of denotation (in my case paper, canvas or wood); and iconic imagery and the depiction of perceptual space that is connotated by marks, colours and forms upon that surface. Most importantly this thesis is concerned with the relationship between these elements and the deconstruction of them. That the reconstruction of the deconstructed language can create expressive iconic structures that perhaps contain conflicting information and elements, but are simultaneously single and self-contained perceptual models of seeing the world, and the things in it, in another way; is a major focus. The thesis is embodied in the paintings and drawings which are documented in the exegesis that follows.

Nutrition, growth and production of Cherax Destructor Clark, 1936 (Decapoda, Parastacidae)

In this study the nutrition, growth and production of C. destructor was examined. Selected nutritional requirements of juvenile animals were determined under controlled conditions with the aim of developing a pelleted diet for use in hatcheries, nurseries and growout situations. The best developed diet was assessed for its potential as a supplementary feed for animals cultured in earthen environments. The protein requirements were first determined simultaneously with an evaluation of the effect of replacing animal protein (fishmeal) by soybean meal. Juveniles were reared communally for 59 d on isoenergetic diets containing 15-30% protein and graded levels of soybean meal (0-60%, of protein). When soybean meal was included at a level of 40-60%, growth was reduced relative to that achieved with control diets containing 15% and 20% protein, but this was not the case at a 20% soybean meal substitution level. A two-way interaction occurred between dietary protein and soybean meal content. Higher protein feeds enabled higher soybean meal inclusion levels without significantly affecting growth. Protein increases of 5% produced better growth at the 40% and 60% soybean meal substitution levels. This effect was less pronounced in the control and the 20% soybean meal diets. Carcass %protein increased and %lipid decreased as dietary protein increased. A similar effect occurred by increasing the soybean meal level to 60%. No obvious trend in carcass moisture, energy, and ash occurred. A protein requirement of 30% was apparent when fish meal and soybean meal were included in diets at levels of 20% and 24% (dry matter) respectively. Alternative protein sources to soybean meal were subsequently identified. Juveniles were maintained for 12 weeks on isoenergetic diets containing 30% protein and differing in the primary source of protein used, with meat, snail, soybean, yabby, and zooplankton meals comprising the major protein ingredient. No significant difference occurred in mean weight (MW), percentage weight gain (%WG), SGR or survival among diets. Food conversion ratios (FCR) were low, with a minimum value of 0.95 for the snail-based diet. The apparent net protein utilisation (ANPU) varied from 29.6% (zooplankton-based diet) to 41.2% (snail-based diet). Carcass composition varied with diet, with the greatest difference occurring in carapace colour. Animals fed the zooplankton-based diet developed the strongest, most natural pigmentation. A new combination of previously used protein-based ingredients was subsequently tested with reference to two yabby species, Cherax albidus and Cherax destructor, that were grown simultaneously in identical conditions. Juvenile male animals were reared individually for 20 weeks on isoenergetic diets containing 15% or 30% protein with fish meal, soybean meal, yabby meal and wheat products forming the basis of the diets. C albidus grew the fastest and utilised the food the most effectively. Carcass composition was influenced by diet with the 30% protein diet resulting in an increase in carcass protein and ash and a decrease in carcass lipid and energy relative to the low protein diet. Carcass moisture and calcium were not affected by diet. The intermoult period (IP) was highly dependent on the premoult weight (W) but the mean moult increment (WI, as weight) was independent of the PM. The orbital carapace length (OCL) and the abdominal length (ABL) %moult increments generally declined with an increase in PM whereas the propus length (PL) %moult increment generally increased. The IP, WI, %OCL, %ABL, and %PL moult increments varied according to diet and to species. Elevated dietary protein caused a reduction to the IP (for similar sized animals) by 11 d and 7 d and an increase to the WI by 85% and 81% in C. albidus and C destructor respectively. Dietary induced morphological changes also occurred. Animals of a standard OCL (both species) had significantly larger abdomens when fed the higher protein diet. Growth on the best developed diet was compared to the growth obtained on a natural diet of freshwater zooplankton. Juveniles were reared individually for 12 weeks on the two diets. The MW, %WG and SGR were higher for the zooplankton diet. Carcass composition was influenced by diet and the zooplankton fed animals had a higher carcass %protein, %lipid, %ash and %fibre content and were more richly pigmented than animals fed pellets. The IP and the WI were highly dependent on the PM and varied according to diet; feeding with zooplankton reduced the IP by 1.2 days and increased the WI by 13.7% compared to pellets. Nutrient digestibility was determined for the pelleted diets evaluated in the growth trials. Protein digestibility (PD) and dry matter digestibility (DMD), using chromic oxide (Cr2O3) as an exogenous marker, were high for all diets, at around 93% and 83% respectively. Ash digestibility varied considerably from 17% to 73% for the snail and yabby meal diets respectively. Crude fibre digestibility was around 50% and probably indicates cellulase activity. Alternative markers to Cr2O3 were evaluated. Ash was considered to be the most suitable alternative to Cr2O3, providing a reasonable, albeit lower, estimate of nutrient digestibility. Cr2O3 and ash were preferentially excreted whereas fibre was retained in the digestive system for a longer period, consequently, the collection of a particular fraction of the deposited faeces (late or early) substantially affected the digestibility coefficients. In earthen-based environments, animals fed the best developed diet were compared to animals cultured using a forage crop of clover (Trifolium repens). Three supplementary feeding strategies representing varying levels of management intensity were evaluated in a series of trials conducted in ponds and pond microcosms. Growth on pellets consistently exceeded that obtained with the forage crop, with final MW being 67-159% higher than that using clover and appeared to be the result of direct pellet consumption and from a pellet fertiliser effect (on the sediment). Within-pond DMD and PD were high and similar for each treatment (DMD = 51-58%; PD = 89-92%). In the control pond, DMD and PD increased with each successive flood. The faecal egestion rate (PER) decreased with each successive flood in all ponds, and is negatively related to animal weight and to foregut fullness (FF) according to power curves. FF was consistently lowest in the control pond. Mean FF was 48.5%, 62.3%, and 26.7% for the pellet, crop and control ponds respectively. FF increased to the third flood in each pond. The foregut protein content was high in all samples and the mean values were 33.9%, 32.7% and 35.6% for the pellet, crop and control ponds respectively. Foregut ash was highly variable within each pond and is inversely related to the foregut protein content. In the control and pellet ponds the highest foregut ash content occurred during flood 1. The culture system (aquaria or pond) strongly influenced the composition of the foregut content. The foregut of animals fed the manufactured diet (B2) in ponds contained approximately 176% more ash and 5% more protein than the foregut of animals fed in bare-bottom tanks. The FF of the tank fed animals was approximately 45% higher than the FF of pond fed animals after a similar feeding period. Base-line yields for extensive production systems appeared to be around 400kg ha-1. The supplementary addition of T. repens produced yields of approximately 635kg ha-1 (in ponds) to around 1086kg ha-1 (in tanks). The sequential addition of cut-clover to tanks stimulated growth to levels approaching those achieved on pellets. Yabbies stocked into ponds at 15-20 m-2 with a mean weight of 2.67g and fed a 30% protein pelleted diet for 100 d, resulted in a yield of approximately 1117kg ha-1, but only 2% of the population were above a marketable size of 50g. The feed utilisation indices were better for animals reared on pellets in bare-bottom tanks than in earthen environments, indicating some degree of pellet wastage when natural feeds are simultaneously present. High apparent food conversion ratios and low protein efficiency ratios occurred when the forage crop was provided. A considerable quantity of the dry matter and protein content of the forage crop was either inefficiently utilised or directed into other production pathways. Sowing a forage crop into pond microcosms to which a pelleted diet was also provided, did not enhance growth performance. Pelleted feed inputs at a rate of approximately 129g m-2 to 198g m-2 (dry matter) and 38g -2 to 64g m-2 (protein) over 70-100 d resulted in acceptable growth and feed utilisation indices for animals reared in ponds and pond microcosms. Forage crop inputs of approximately 533g m-2 to 680g m-2 (as dry matter) or 84g m-2 to 177g m-2 (as protein) over a 70-100 d period produced reasonable growth rates but poor feed utilisation indices. Low inputs of dry matter (from 113-296g m-2) and protein (from 24-54g m-2) from clover were sufficient to maintain high growth rates in pond microcosms for around 28 d. In ponds, a very low level of 21g m-2 (dry matter) and 4.3g m-2 (protein) was sufficient for around 3 weeks. Forage depletion appeared to occur beyond week 3-4 and was probably a major growth limiting factor. The mean hepatosomatic index (HSI) was 9.44, 7.68, and 6.79 for the pellet, crop, and control ponds respectively. The relationship between hepatopancreas weight and overall animal weight was significantly different between treatments. The hepatopancreas of pellet-fed animals had the highest %lipid and lowest %ash, %protein, %carbohydrate and %moisture content. In terms of absolute quantities, the only major difference in hepatopancreas composition between treatments occurred for lipid and dry matter content. The hepatopancreas of the pellet-fed animals was a cream/cream-yellow colour and was very fragile, whereas in the other ponds it was a more ‘natural’ bright yellow colour and was structurally more robust. C. destructor has a capacious foregut, being approximately 5 times the volume of similar sized Penaeids. The foregut volume (V, ml) of the yabby is related to animal weight (W, g) according to V = 0.048 W0.9543. Animals that were starved for 96 h and then fed diet B2 were almost completely foil after 30 min. The ‘apparent enzymatic response’ of animals fed various natural and artificial diets in tanks was evaluated. Nutrient processing time and the enzymatic response following ingestion appeared to be regulated by the chemical and physical properties of the diet. For the natural feeds, foregut protein was 1.2% higher (for zooplankton) and up to 300% higher (for detritus) than dietary protein, whereas ash was 7.5% higher (zooplankton) and 46-63% lower (detritus) than dietary ash. For animals fed diet B2 after 48 h without food, FF was approximately half that of 96 h starved animals after a similar feeding period but foregut protein and ash contents were similar. Finally, the physiological and morphological attributes elucidated in this study are discussed with reference to the ecology of the yabby. High growth rates, excellent feed utilisation indices and high digestibility coefficients for a wide range of diet-types illustrate nutritional flexibility. A capacious foregut, a large hepatopancreas with a high energy storage capacity, the ability to partition and preferentially excrete the low nutrient value inorganic component of the diet, the capacity to alter body form, nutrient processing time and enzymatic secretions in relation to diet-type, and modified behaviour according to feed availability also demonstrate plasticity/adaptability/flexibility. The combined effect of these important characteristics ensures survival in environments that may be adverse and highly variable in terms of nutrient availability. Collectively the morphological and digestive traits elucidated in this study reflect the generalist-type nature of C destructor and indicate that a polytrophic classification still seems appropriate. Several priority areas for further nutrition research are identified and recommendations are made regarding the best-practices to use in the commercial culture of the yabby. Of paramount importance is the further clarification of the nutritional requirements and feeding preferences of animals in various phases of development.

Envisioning Indochina : the spatial and social ordering and imagining of a French colony

The emergence of Indochina in the French imagination was articulated in both representational and institutional modes. Representation involves the transmission of colonial ideals through more obtuse means; that is, through literary texts, travelogues, exhibitions, film and advertising. However, these textual sites feed from and invest in a material situation, which was the institutional arm of colonialism. Indochina was institutionally articulated in cartographic maps and surveys, in the new social spaces of cities and towns, in architectural and technological forms, through social technologies of discipline and welfare and in cultural and religious organisations. The aim of this thesis is to analyse, across a number of textual sites, the representation and institutionalisation of Otherness through the politics of space in the French colony of Indochina, Indochine in this sense becomes a spatial discourse. The French constructed a mental and physical space for Indochina by blanketing and suffocating the original cultural landscape, which in fact had to be ignored for this process to occur. What actually became manifest as a result of this projection stemmed from the French imagination. Just as the French manipulated space, language also underwent the same process of reduction. The Vietnamese script was latinised to make it more 'useable' and ‘accessible’. Through christening the union of Indochina; initiating a comprehensive writing reform; and renaming the streets in the colonial cities, the French used language us another tool for 'making transparent'. Furthermore, the colonial powers established a communication and transport network throughout the colony in an attempt to materialise their fictive (artificial) vision of a unified French Indochinese space. The accessibility and design of these different modes of transport reflected the gendered, racial and class divisions inherent in the colonial establishment. At the heart of representing and institutionalising Indochina was the desire to control and contain. This characterised French imperial ordering of space in the city and the rural areas. In rural areas land was divided into small parcels and alienated to individuals or worked into precise grids for the rubber plantation. In urban centres the native quarter was clearly demarcated from the European quarter which functioned as its modern, progressive Other. The rationale behind this segregation was premised on European, nineteenth century discourses of race, class, gender and hygiene. Influenced by Darwinian and neo-Lamarkian theories of race, this biological discourse identified the 'working class', 'women' and 'the native' as not only biologically but also culturally inferior. They were perceived as a potential, degenerative threat to the biological, cultural and industrial development of the nation. In the colonial context, space was thus ordered and domesticated to control the native population. Coextensively, the literature which springs from such a structure will be tainted by the same ideas, and thus the spaces it formulates within the readers mind feed on and reinforce this foundation. Examples of gender and indigenous narratives which contest this imaginative, transparent topography are analysed throughout this thesis. They provide instances of struggle and resistance which undermine the ideal/stereotypical level of architectural and planned space and delineate an alternative insight into colonial spatial and social relations. The fictional accounts of European women and indigenous writers both challenge and reaffirm the fixity of some of these idealised colonial boundaries. In various literary, historical, political, architectural and cinematic discourses Indochina has been und continues to be depicted as a modern city and exotic Utopia. Informed by the mood of nostalgia, exotic images of Indochina have resurfaced in contemporary French culture. France's continued desire to create, control and maintain an Indochinese space in the French public imagination reinforces the multi-layered, interconnected and persistent nature of colonial discourse.

Re-engaging learners in schooling through applied learning reform : exploring the Victorian Certificate of Applied Learning as an 'alternative' senior schooling pathway in Australia

The Victorian Certificate of Applied Learning (VCAL) emerged in Australia to provide more relevant curriculum programs that would cater for increasing retention rates of high school students. It is also an example of the ‘new’ learning arising from contemporary debates and reforms that highlight inadequacies of the more traditional modes of learning. This book focuses on the pedagogical and sociological issues emerging from the VCAL being introduced as an ‘alternative’ learning pathway for ‘at-risk’ students within a traditional high school culture. Through the eyes of an insider- researcher, the book argues for a deeper understanding of applied learning as a ‘re-engaging’ pedagogy by studying the schooling experience of VCAL students and teachers. The book concludes that traditional modes of school teaching contribute to the social construction of ‘at-risk’ students and argues that high school pedagogy needs to be redefined as a cultural phenomenon requiring teachers to be reflexively aware of their role in bridging the gap between students’ life experiences and the curriculum.

An alternative approach to understanding second-order conditions for constrained optimization - lagrange multipliers

This paper presents an alternative approach to solving a standard problem, frequently encountered in advanced microeconomics, using the technique of Lagrange multipliers. The objective is to enhance the understanding of students as to the derivation of the second-order conditions.

Alternative naming strategies : family versus individual brand names

Increased competition in the consumer goods marketplace has resulted in too many brands chasing too few consumers. In an attempt to ease pressure on margins, and both brand and product range profitability, marketers would be well advised to reinspect their policies towards brand naming and the attendant costs associated with those policies. Is it really necessary for each new product to be individually named? If it is, then what are the strategic and financial implications of this decision? Why is it that the practice in some companies is to resort to a string of unrelated brand names whereas the practice elsewhere is to use an umbrella family name, with or without, a brand name as a suffix? The answers to such questions are by no means obvious and closer inspection of the issues relating to naming policy fails to yield any consensus let alone a definitive approach. This article seeks to depict the alternative naming strategies engaged by marketers and to focus on those considerations that would favour a family name in preference to an individualised brand name. The article concludes with recommendations that are drawn from current literature and the experience of marketers with a view to determining those circumstances that may influence the formulation of a more appropriate naming policy.

Teacher education and critical inquiry : the use of activity theory in exploring alternative understandings of language and literacy

This paper explores the challenges of espousing a critical pedagogy within the managerial climate that presently shapes teacher education. It argues that current discourses of professionalism are incommensurate with a view of literacy as social practice and that they disregard complex semiotic ecologies in which both school and university students operate. Graduate teachers are constructed as the ‘providers’ of decontextualised literacy skills to school students whose existing communication networks are ignored. Rejecting this narrow view of professional practice, we draw on activity theory to analyse the social configuration of tertiary students’ identities and the textual resources that mediate their professional learning. This kind of research is needed to reveal the contradictions within and between activity systems in which tertiary students participate as well as to construct possible solutions to the contradictions identified.

Teacher education and critical inquiry : the use of activity theory in exploring alternative understandings of language and literacy

This article explores the challenges of espousing a critical pedagogy within the managerial climate that presently shapes teacher education. Current discourses of professionalism are incommensurate with an understanding of the way that literacy practices are grounded in the social worlds in which both school and university students operate. Such discourses construct graduate teachers as the providers of decontextualised literacy skills to school students whose existing communication networks are ignored. We argue that an alternative understanding of professional practice can be developed by focusing on the textual resources university students use to mediate their learning, and by locating their emerging professional identities within the activity systems and meaning-making practices in which they participate.