Comparison of the color stability and lipid oxidative stability of fresh and vacuum packaged lamb muscle containing elevated omega-3 and omega-6 fatty acid levels from dietary manipulation

A series of three experiments were conducted with second cross ([Merino&times;Border Leicester]&times;Poll Dorset) wether lambs to evaluate the effects of dietary treatments on manipulation of muscle long-chain (LC) omega-3 fatty acids (FA) on the color stability and oxidative stability of fresh and vacuum packaged lamb. At the end of 7-, 6- and 6-week experimental periods for experiments (Exp.) 1–3 respectively, lambs were slaughtered at a commercial abattoir. At 24 h post-mortem, muscle longissimus lumborum (LL) and longissimus thoracis (LT) were removed and evaluated for color and lipid oxidative stability under specified commercial storage and display condition. Of the dietary supplements used, fish meal and fish oil moderately (P&lt;0.01) and markedly (<i>P&lt;i>0.001) increased muscle omega-3 FA content, while both protected canola seed (<i>P&lt;i>0.001) and protected sunflower meal protein significantly (<i>P&lt;i>0.02) increased muscle omega-6 FA content or ratio of omega-6/omega-3 of the longissimus muscle. In all experiments, the substantial increase (<i>P&lt;i>0.001) in muscle LC omega-3 and omega-6 FA had no consistent significant effect on color values (redness (<i>a*i>), yellowness (<i>b*i>) and lightness (<i>L*i>)) for fresh and vacuum packaged lamb over a 6-day display period. Lipid oxidation, determined by the levels of thiobarbituric acid reactive substances (TBARS) indicated the enrichment of muscle polyunsaturated fatty acid (PUFA) levels in lambs did not produce significant differences resulting either from main treatment effects or for treatment&times;day&times;type interactions (where type was fresh and vacuum packaged). Present results demonstrated the color and lipid oxidative stability of lamb longissimus muscle during refrigerated display was not affected by enhanced levels of omega-3 and omega-6 FA due to dietary treatments.

Historical dynamics of the fur seal population : evidence of regulation by man?

The Australian fur seal (Arctocephalus pusillus doriferus) was severely over-exploited in the 18th and 19th centuries and until relatively recently its population had remained steady at well below estimated presealing levels. However, the population is now increasing rapidly (6%–20% per annum) throughout its range and there is a need to understand its dynamics in order to assess the potential extent and impact of interactions with fisheries. Age distribution (n = 156) and pregnancy rate (n = 110) were determined for adult females collected at a breeding colony on Seal Rocks, southeast Australia, in 1971–1972. Mean &plusmn; SE and maximum observed ages were 9.37 &plusmn; 0.41 and 20 years (n = 1), respectively. A stochastic modelling approach was used to fit an age distribution to the observed age-structure data and calculate rates of recruitment and adult survival. Annual adult female survival and recruitment rates between 1954 and 1971 were 0.478 &plusmn; 0.029 (mean &plusmn; SE) and 0.121 &plusmn; 0.007, respectively, suggesting that the population was experiencing a decline during the 1960s. The pregnancy rate increased from 78% at 3 years of age to an average of 85% between 4–13 years of age before significantly decreasing in older females (the oldest was 19 years of age). There was no significant effect of body mass or condition on the probability of a female being pregnant (P > 0.5 in both cases) and the nutritional burden of lactation did not appear to affect pregnancy rates or gestational performance. These findings suggest that the low survivorship was due to density-independent effects such as mortality resulting from interactions with fishers, which are known to have been common at the time. The recent increase in the population is consistent with anecdotal evidence that such interactions have decreased as fishing practices have changed.

Variation in plasma leptin levels in response to fasting in Antarctic fur seals (Arctocephalus gazella)

Plasma leptin levels were determined in 8 lactating female and 20 pup Antarctic fur seals (<i>Arctocephalus gazellai>) during fasting periods of normal duration. Plasma leptin levels ranged from 1.35-3.19 ng&middot;ml<sup>-1 in lactating females and 1.79-4.80 ng&middot;ml<sup>-1 in pups and were not positively correlated with body mass or condition. A negative trend, however, was observed between plasma leptin levels and body condition in lactating females upon their arrival at the colony following a foraging trip (beginning of fast). In accordance with findings in other species, plasma leptin levels dropped significantly (P&lt;0.02) in response to the 17-19% drop in body mass experienced by pups during fasting. In contrast, plasma leptin levels in lactating females increased during the first 24 h of fasting before decreasing throughout the remaining 48 h of the fast. This unexpected result could be due to the high level of energy expenditure by seals as they swim back to the colony (i.e. post-exercise response) or may be influenced by the intense suckling activity experienced by females during the onshore fasting periods. The results of this study support recent findings in other carnivore species which suggest the primary physiological role of leptin in these species may not necessarily be as a signal of the magnitude of body energy reserves.

Effect of carotenoids and background colour on the skin pigmentation of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

Three 2-factor experiments were conducted to determine the effects of background colour and synthetic carotenoids on the skin colour of Australian snapper Pagrus auratus. Initially, we evaluated the effects on skin colour of supplementing diets for 50 days with 60 mg kg^&minus;1 of either astaxanthin (LP; Lucantin^®Pink), canthaxanthin (LR; Lucantin^® Red), apocarotenoic acid ethyl ester (LY; Lucantin^® Yellow), selected combinations of the above or no carotenoids and holding snapper (mean weight=88 g) in either white or black cages. In a second experiment, all snapper (mean weight=142 g) from Experiment 1 were transferred from black to white, or white to white cages to measure the short-term effects of cage colour on skin <i>L*i>,<i> a*i> and <i>b*i> colour values. Skin colour was measured after 7 and 14 days, and total carotenoid concentrations were determined after 14 days.

Cage colour was the dominant factor affecting the skin lightness of snapper with fish from white cages much lighter than fish from black cages. Diets containing astaxanthin conferred greatest skin pigmentation and there were no differences in redness (<i>a*i>) and yellowness (<i>b*i>) values between snapper fed 30 or 60 mg astaxanthin kg^&minus;1. Snapper fed astaxanthin in white cages displayed greater skin yellowness than those in black cages. Transferring snapper from black to white cages increased skin lightness but was not as effective as growing snapper in white cages for the entire duration. Snapper fed astaxanthin diets and transferred from black to white cages were less yellow than those transferred from white to white cages despite the improvement in skin lightness (<i>L*i>), and the total carotenoid concentration of the skin of fish fed astaxanthin diets was lower in white cages. Diets containing canthaxanthin led to a low level of deposition in the skin while apocarotenoic acid ethyl ester did not alter total skin carotenoid content or skin colour values in snapper.

In a third experiment, we examined the effects of dietary astaxanthin (diets had 60 mg astaxanthin kg^&minus;1 or no added carotenoids) and cage colour (black, white, red or blue) on skin colour of snapper (mean weight=88 g) after 50 days. Snapper fed the astaxanthin diet were more yellow when held in red or white cages compared with fish held in black or blue cages despite similar feed intake and growth. The skin lightness (<i>L*i> values) was correlated with cage <i>L</i>* values, with the lightest fish obtained from white cages. The results of this study suggest that snapper should be fed 30 mg astaxanthin kg^&minus;1 in white cages for 50 days to increase lightness and the red colouration prized in Australian markets.

Effects of cage netting colour and density on the skin pigmentation and stress response of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

The unnaturally dark pigmentation of cultured Australian snapper Pagrus auratus can be improved through dietary astaxanthin supplementation and by holding fish in tanks with a white background. The practical application of these  laboratory-based findings was examined with two experiments to establish if the advantages of transferring fish to light coloured tanks before harvest could be achieved on-farm using white cages and to determine the effects of fish density on skin colour. For the first experiment, snapper (mean TL=29.7 cm) were transferred from a commercial snapper sea cage to black or white netted cages and fed diets supplemented with unesterified astaxanthin (supplied as Lucantin^® Pink, BASF) at 0 or 39 mg kg^&minus;1 for 42 days. Skin colour was measured using the CIE <i>L* i>(black–white), <i>a*i> (green–red), <i>b*i> (blue–yellow) colour scale. Snapper held in white netting cages became significantly lighter (higher <i>L*i> ) than snapper held in black cages; however, values were not as high as previous laboratory-based studies in which snapper were held in white plastic-lined cages. Snapper fed astaxanthin displayed significantly greater <i>a*i>and <i>b*i> values, and total carotenoid concentrations after 42 days. In addition, total carotenoids were higher in fish from black than white cages. The second experiment was designed to investigate whether density reduced the improvements in skin colour achieved by holding fish in white coloured cages and whether cage colour affected stress. Snapper (mean weight=435 g) were acclimated to black cages and fed 39 mg kg^&minus;1 astaxanthin for 44 days before transferring to black or white plastic-lined cages at 14 (low), 29 (mid) or 45 (high) kg m^&minus;3 for 7 days after which time skin colour, plasma cortisol and plasma glucose concentrations were measured. Skin lightness (<i>L*i> ) was greater in snapper transferred to white plastic-lined cages with the lightest coloured fish obtained from the lowest density after 7 days. Density had no effect on plasma cortisol or glucose levels after 7 days, although plasma cortisol was elevated in snapper from black cages. For improved skin colouration we recommend feeding unesterified astaxanthin at 39 mg kg^&minus;1 for approximately 6 weeks and transferring snapper to white plastic-lined cages or similar at low densities for short periods before harvest rather than producing fish in white netting sea cages subject to biofouling.

Cage colour and post-harvest K+ concentration affect skin colour of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

In an attempt to improve post-harvest skin colour in cultured Australian snapper <i>Pagrus auratusi>, a two-factor experiment was carried out to investigate the effects of a short-term change in cage colour before harvest, followed by immersion in K⁺-enriched solutions of different concentrations. Snapper supplemented with 39 mg unesterified astaxanthin kg^&minus;1 for 50 days were transferred to black (for 1 day) or white cages (for 1 or 7 days) before euthanasia by immersing fish in seawater ice slurries supplemented with 0, 150, 300, 450 or 600 mmol L<sup>&minus;1 K⁺ for 1 h. Each treatment was replicated with five snapper (mean weight=838 g) held individually within 0.2 m³ cages. <i>L*i>, <i>a*i> and <i>b*i> skin colour values of all fish were measured after removal from K⁺ solutions at 0, 3, 6, 12, 24 and 48 h. After immersion in K⁺ solutions, fish were stored on ice. Both cage colour and K⁺ concentration significantly affected post-harvest skin colour (<i>P&lt;i>0.05), and there was no interaction between these factors at any of the measurement times (<i>P>i>0.05). Conditioning dark-coloured snapper in white surroundings for 1 day was sufficient to significantly improve skin lightness (<i>L*i>) after death. Although there was no difference between skin lightness values for fish held for either 1 or 7 days in white cages at measurement times up to 12 h, fish held in white cages for 7 days had significantly higher <i>L*i> values (i.e. they were lighter) after 24 and 48 h of storage on ice than those held only in white cages for 1 day. K⁺ treatment also affected (improved) skin lightness post harvest although not until 24 and 48 h after removal of fish from solutions. Before this time, K⁺ treatment had no effect on skin lightness. Snapper killed by seawater ice slurry darkened (lower <i>L*i>) markedly during the first 3 h of storage in contrast with all K⁺ treatments that prevented darkening. After 24 and 48 h of storage on ice, fish exposed to 450 and 600 mmol L<sup>&minus;1 K⁺ were significantly lighter than fish from seawater ice slurries. In addition, skin redness (<i>a*i>) and yellowness (<i>b*i>) were strongly dependent on K⁺ concentration. The initial decline in response to K⁺ was overcome by a return of <i>a*i> and <i>b*i> values with time, most likely instigated by a redispersal of erythrosomes in skin erythrophores. Fish killed with 0 mmol L<sup>&minus;1 K⁺ maintained the highest <i>a*i> and <i>b*i> values after death, but were associated with darker (lower <i>L*i>) skin colouration. It is concluded that a combination of conditioning snapper in white surroundings for 1 day before harvest, followed by immersion in seawater ice slurries supplemented with 300–450 mmol L<sup>&minus;1 K⁺ improves skin pigmentation after >24 h of storage on ice.

Influence of temperature on evaporative water loss and cutaneous resistance to water vapour diffusion in the orange-thighed frog (Litoria xanthomera)

We evaluated the effect of ambient temperatures between 25 and 43°C on the rate of evaporative water loss (EWL) in eight adult <i>Litoria xanthomerai> (average body mass = 7.3 &plusmn; 0.6 g). Frogs were placed in a cylindrical chamber that permitted them to fully conceal their ventral surfaces using a water-conserving posture. Their EWL was 7.1 &plusmn; 0.7 mg g^–1 h^–1 at 25°C and reached 28.0 &plusmn; 2.5 mg g^–1 h^–1 at 43°C. Agar replicas of the frogs were used to evaluate boundary-layer resistances associated with the EWL measurements and, thus, to permit evaluation of cutaneous resistance to vapour diffusion (r_c) in live frogs. The r_c of <i>L. xanthomerai> was stable over the temperature range of 25–35°C, averaging about 28 s cm^–1, and then declined stepwise with ambient temperatures above 37°C. The highest r_c recorded for each individual over the range of temperatures studied averaged 32.0 &plusmn; 1.2 s cm^–1. The thermolabile nature of r_c demonstrates a well developed thermoregulatory control of EWL in this species, a trait very similar in pattern and extent to that previously measured in the closely related <i>Litoria chlorisi>.

Do green and golden bell frogs (Litoria aurea) occupy habitats with fungicidal properties?

The Green and Golden Bell frog <i>Litoria aureoi> is in major decline in Australia, where its distribution is now confined mainly to the east coast of New South Wales (NSW). Infection by the newly emerged amphibian fungal pathogen <i>Batrachochytrium dendrobatidisi> has been identified as one of the main threats affecting <i>L. aureai>. Surprisingly, some of the sites in NSW sustaining the largest populations of this species are industrial and urban habitats that are often disturbed and polluted, which could protect <i>L. aureai> from chytrid infection if pollution had fungicidal capacity.The aim of this study was to characterise the trace metal concentration of several <i>L. aureai> breeding sites in the Sydney and IIlawarra regions of NSW and to evaluate the fungicidal efficacy of the main "'ace metals identified. Selected <i>L. aureai> sites were sampled throughout the breeding season (September to February) to establish the concentration of trace metals in both surface sediment and waters. Physico-chemical parameters including pH and salinity were also measured. Of the trace metals identified, copper and zinc were consistently elevated across sites. Over 50% of sites exceeded the National Sediment Quality Guideline for both copper and zinc concentration, and over 90% of sites exceeded the National Water Quality Guideline for these metals. Consequently, we evaluated their effect on the growth and survival of a laboratory culture of B. dendrobatidis,These tests were performed in media containing dissolved metal concentrations of 0.02 - 0.65 mgL<sup>-1 Cu and 0.24 - 5.0 mgL<sup>-1 Zn. Growth rates were inferred by total fungal density in liquid culture (based on spectral absorbance measurements), final dry weight, and the density of zoospores in fungal cultures grown for 28 days. Both copper and zinc were found to reduce the growth and proliferation of <i>B. dendrobatidisi>, but in a non-linear manner. This suggests that <i>L. aureai> may be gaining some protection from <i>B. dendrobatidisi> infection at several of the sites examined.

Changes in skin colour and cortisol response of Australian snapper Pagrus auratus (Bloch & Schneider, 1801) to different background colours

A two-factor experiment was carried out to investigate the change in skin colour and plasma cortisol response of cultured Australian snapper Pagrus auratus to a change in background colour. Snapper (mean weight=437 g) were held in black or white tanks and fed diets containing 39 mg unesterified astaxanthin kg^&minus;1 for 49 days before being transferred from white tanks to black cages (WB) or black tanks to white cages (BW). Skin colour values [<i>L<sup>*i> (lightness), <i>a^*i> (redness) and <i>b^*i> (yellowness)] of all snapper were measured at stocking (<i>ti>=0 days) and from cages of fish randomly assigned to each sampling time at 0.25, 0.5, 1, 2, 3, 5 and 7 days. Plasma cortisol was measured in anaesthetized snapper following colour measurements at 0, 1 and 7 days. Fish from additional black-to-black (BB) and white-to-white (WW) control treatments were also sampled for colour and cortisol at those times. Rapid changes occurred in skin lightness (<i>L<sup>*i> values) after altering background colour with maximum change in <i>L<sup>* i>values for BW and WB treatments occurring within 1 day. Skin redness (<i>a*i>) of BW snapper continued to steadily decrease over the 7 days (<i>a*i>=7.93 &times; e^{&minus;0.051 &times; time}). Plasma cortisol concentrations were highest at stocking when fish were held at greater densities and were not affected by cage colour. The results of this study suggest that transferring dark coloured snapper to white cages for 1 day is sufficient to affect the greatest benefit in terms of producing light coloured fish while minimizing the reduction in favourable red skin colouration.

Staff and student perceptions of an online learning environment : difference and development

Academic staff play a fundamental role in the use of online learning by students. Yet, compared to studies reporting student perspectives on online learning, studies investigating the perspectives of academic staff are much more limited. Perhaps the least common investigations are those that compare the perceptions of academic staff and students using the same online learning environment (OLE). Much research indicates, at least initially, academic staff most value OLE systems as a mechanism for efficient delivery of learning materials to students. Following the mainstreaming of an OLE at Deakin University in 2004, the data from a large, repeated, representative and quantitative survey were analysed to investigate comparative staff and student evaluations of an OLE, and to explore the evidence for development in the use of an OLE by academic staff. Generally, students were found to give higher importance and satisfaction ratings to elements of the OLE than staff. Students were also more likely than staff to agree that the OLE enhanced their learning. A comparison of the mean ratings recorded for staff in 2004 and 2005 showed that both importance and satisfaction ratings of elements of the OLE were almost universally higher after a year of use of the OLE.

Use of phosphite as a control for Phytophthora cinnamomi in southeastern Victorian vegetation communities

One of the major aims of the research presented in this thesis was to assist managers of native vegetation communities in southeastern Australia in understanding the dynamics of P. cinnamomi with an important ecological species, Xanthorrhoea australis. It trialed the use of phosphite in large-scale field applications to establish the usefulness of this management option for the first time on Victorian flora. This thesis describes the process of disease development within mature X. Australia plants. For the first time it was shown that within X. australis plants, secondary disease symptoms are related to the percentage of stem that has been infested by the disease. It was evident that after initial invasion the pathogen moves via root xylem and throughout the plant within vascular to the stem, especially within the desmium. The research shows that the pathogen could not be isolated consistently even though it was considered to be responsible for disease symptoms. Trials of a control fungicide (Foli-R-fos 200) shows that protection occurs in many susceptible plants when 2 and 6g a.i./L phosphite is applied. Phytotoxicity occurred in native plants at Anglesea and within controlled environment trials when using ≥ 6g a.i./L. It will be shown that 2g a.i./L phosphite controls disease in sprayed plots within heathlands at Anglesea and a recently burnt coastal woodland community at Wilson’s Promontory. The proportion of healthy X. australis plants treated with phosphite was significantly higher than the proportion in control plots without phosphite. The research shows that phosphite was recovered from leaves of three species treated with Foli-R-fos 200 in the field. For the first time it has been shown that seed germination was reduced in two species when high concentrations of phosphite were applied. The first documentation of the effect that phosphite has on soil properties showed that nitrogen and oxidised organic carbon were the only parameters to alter significantly. This thesis provides answers to some important questions, answers that can now be used by managers in formulating better policies and actions at an operational level. There has been a dire need in Victoria to address many issues regarding P. cinnamomi and this thesis provides relevant and informative approaches to disease control, and a better understanding of the disease progress.

Polymer electrolytes for electrochromic window applications

Polymer electrolytes suitable for use in electrochromic window devices for architectural applications have been developed. The electrolyte properties required for a large area, long lifetime, long cycle life and wide temperature range application such as this place some restrictions on the type of polymer system required. The electrolytes developed in this work are based on LiClO₄ in a polyether copolymer which is cured in place to produce a clear elastomer. The material properties and conductivity of electrolytes with and without the plasticizers are presented. Electrochromic device performance tests show that the electrolyte impedance is a factor in the device performance, but not the limiting factor.

Ageing mallee eucalypt vegetation after fire : insights for successional trajectories in semi-arid mallee ecosystems

A critical requirement in the ecological management of fire is knowledge of the age-class distribution of the vegetation. Such knowledge is important because it underpins the distribution of ecological features important to plants and animals including retreat sites, food sources and foraging microhabitats. However, in many regions, knowledge of the age-class distribution of vegetation is severely constrained by the limited data available on fire history. Much fire-history mapping is restricted to post-1972 fires, following satellite imagery becoming widely available. To investigate fire history in the semi-arid Murray Mallee region in southern Australia, we developed regression models for six species of mallee eucalypt (<i>Eucalyptusi> <i>oleosai> F.Muell. ex. Miq. subsp. <i>oleosa, E. leptophylla i>F.Muell. ex. Miq., <i>E.i> <i>dumosai> J. Oxley, <i>E. costata i>subsp. <i>murrayana i>L. A. S. Johnson & K. D. Hill, <i>E. gracilisi> F.Muell. and <i>E. socialisi> F.Muell. ex. Miq.) to quantify the relationship between mean stem diameter and stem age (indicated by fire-year) at sites of known time since fire. We then used these models to predict mean stem age, and thus infer fire-year, for sites where the time since fire was not known. Validation of the models with independent data revealed a highly significant correlation between the actual and predicted time since fire (r = 0.71, P &lt; 0.001, <i>ni> = 88), confirming the utility of this method for ageing stands of mallee eucalypt vegetation. Validation data suggest the models provide a conservative estimate of the age of a site (i.e. they may under-estimate the minimum age of sites >35 years since fire). Nevertheless, this approach enables examination of post-fire chronosequences in semi-arid mallee ecosystems to be extended from 35 years post-fire to over 100 years. The predicted ages identified for mallee stands imply a need for redefining what is meant by &lsquo;old-growth’ mallee, and challenges current perceptions of an over-abundance of &lsquo;long-unburnt’ mallee vegetation. Given the strong influence of fire on semi-arid mallee vegetation, this approach offers the potential for a better understanding of long-term successional dynamics and the status of biota in an ecosystem that encompasses more than 250 000 km² of southern Australia.

Marking machinima : a case study in assessing student use of a Web 2.0 technology

The model of learning best suited to the future may be one which sees learning as the process of managing the different kinds of participation an individual might have in complex social systems. Learning capability and engagement is thus dependent on the relationship between an individual identity and social systems. We report on the incorporation of machinima, a Web 2.0 technology, as part of an interdisciplinary and collaborative project where the focus is not on the mastery of the tools or the acquisition of predetermined knowledge, but on the development of learning engagement. We provide the case study of a pilot project involving students across two Arts disciplines collaborating via the game, World of Warcraft, to produce an animated adaptation of one of Geoffrey Chaucer's Canterbury Tales. Their contributions were differently assessed according to the pre-existing requirements of their home disciplines. We argue that the assessment in such projects, in conjunction with innovations and experimentation with Web 2.0 technologies, should shift from an emphasis on product to process. We believe that this has a sound pedagogical and theoretical foundation, and also fits better with the increasingly digitalised, unfixed and interdisciplinary world that students will face on graduation.