A Comparison of Various Seaweed-Based Diets and Formulated Feed on Growth Rate of Abalone in a Land-Based Aquaculture System

The effects of different diets on growth in the cultured South African abalone, Haliotis midae (Linnaeus), was investigated. Growth of juvenile Haliotis midae was monitored on a commercial abalone farm over a period of 9 months in an experiment consisting of 9 treatments with 4 replicates (n = 250 individuals per replicate). The treatments were: fresh kelp (Ecklonia maxima) blades (seaweed control); Abfeed^® (formulated feed control); kelp + Abfeed^® dried kelp pellets; dried kelp blades; dried kelp stipes; fresh kelp with the epiphyte Carpoblepharis flaccida; a mixed diet (Gracilaria gracilis, Ulva lactuca, and kelp) and a rotational diet (abalone were fed 1 of the 9 treatments for the first week and them kelp for the next 3 weeks). Results show that abalone grow well on all fresh seaweed combinations, but grow best on a mixed diet. The likely reason for the success of the mixed diet is that the red and green seaweed was farm grown, with an increased protein content. Dried kelp in any form produced poor growth. Abalone fed on the mixed diet grew at 0.066 mm day^?1 shell length and 0.074 g day^?1 body weight; this corresponds to 24.09 mm shell length and 27.01 g body weight increase per annum. Abalone fed on dried kelp grew at only 0.029 mm day^?1 shell length and of 0.021 g day^?1 body weight. Abalone grown on Abfeed^® grew at 0.049 mm day^?1 shell length and 0.046 g day^?1 body weight which corresponds to 17.88 mm and 16.79 g increase per annum; this is better than the dried seaweed feeds, but poorer than the fresh seaweed combinations. This study shows that seaweed diets, particularly if the diets include seaweeds grown in animal aquaculture effluent, are good substitutes for the formulated feed generally used today.     

Intermittent aeration affects the bioremediation potential of two red algae cultured in finfish effluent

The high cost of aeration needed to tumble culture macroalgae is a limiting factor for integration with land-based finfish culture. Toward reducing this electricity cost, we compared intermittent aeration (16 h on:8 h off) with continuous aeration (24 h on) on the productivity of two strains of Chondrus crispus (Basin Head and Charlesville) and Palmaria palmata from Atlantic Canada between May and June 2011. Algal fronds were cultured under a 16:8-h light/dark photoperiod in 50-L tanks supplied with finfish effluent (49 μmol L^?1 of ammonium and 11 μmol L^?1 of phosphate) at a mean water flow rate of 0.4 L min^?1. Nitrogen (N) influx was 1.8 gN m^?2 day^?1, and phosphorus (P) influx was 0.9 gP m^?2 day^?1, with uptake rates ranging from 0.02 to 2.4 gN m^?2 day^?1 and ?0.2 to 0.4 gP m^?2 day^?1. On average, the macroalgae culture system (algae and biofilms) removed 1.0 gN m^?2 day^?1 (51.9 %). The growth of macroalgae (pooled across treatment and strain) ranged from 0.5 to 1.6 % day^?1, which accounted for a yield of 2.2 to 5.4 g DW m^?2 day^?1. Switching off aeration at night improved the growth rate of Basin Head Chondrus by 146 % and had no effect on growth rate or nitrogen and carbon removal by P. palmata and Charlesville Chondrus. Growth and yield of Basin Head Chondrus under intermittent aeration were over two times greater than both Charlesville Chondrus treatments.     

Ulva lactuca and U. flexuosa (Chlorophyta,Ulvophyceae) cultivation in Brazilian tropical waters: recruitment,growth, and ulvan yield

Ulva spp. are used in a wide range of commercial applications, including bioremediation, food, bioenergy, pharmaceuticals, and agriculture. The sulfated polysaccharide ulvan obtained from Ulva spp. is of interest for triggering plant defenses against disease. However, the cultivation of Ulva spp. is still in its infancy. This study verified the feasibility of cultivating Ulva lactuca and Ulva flexuosa at two sites on the tropical Brazilian coast. We investigated the following: (a) methods to induce sporulation, (b) comparison of seeding ropes inoculated in vitro versus seeding at sea over 40 days, (c) production and harvest cycles at 15 and 30 days, (d) growth productivity of U. flexuosa at sea and in outdoor tanks, and (e) comparison of ulvan yields from biomass cultivated in tanks and the sea. High nutrient treatment was the most efficient method to induce sporulation (7,540?±?3,133 spores m^?1). Sea-based cultivation of U. flexuosa was only successful at one site. Seeding of ropes in vitro was more efficient than seeding at sea (0.31?±?0.20 g m^?2 day^?1), and 15-day harvest cycles were most efficient (20.1?±?1.8 % day^?1; 0.46?±?0.11 g m^?2 day^?1). Despite differences in plant growth in tanks (27.9?±?4.4 % day^?1) and at sea (20.1?±?1.8 % day^?1), the dry biomass and ulvan yields (17.7?±?5.0 %) did not differ between these systems. Cultivation of U. flexuosa was feasible at sea using in vitro seeding with a production cycle of 15 days in Brazilian tropical waters and tanks with high irradiance and enriched seawater.     

Inorganic carbon and pH effect on growth and lipid productivity of Tetraselmis suecica and Chlorella sp (Chlorophyta) grown outdoors in bag photobioreactors

There has been considerable interest in cultivation of green microalgae (Chlorophyta) as a source of lipid that can alternatively be converted to biodiesel. However, almost all mass cultures of algae are carbon-limited. Therefore, to reach a high biomass and oil productivities, the ideal selected microalgae will most likely need a source of inorganic carbon. Here, growth and lipid productivities of Tetraselmis suecica CS-187 and Chlorella sp were tested under various ranges of pH and different sources of inorganic carbon (untreated flue gas from coal-fired power plant, pure industrial CO₂, pH-adjusted using HCl and sodium bicarbonate). Biomass and lipid productivities were highest at pH 7.5 (320?±?29.9 mg biomass L^?1 day^?1and 92?±?13.1 mg lipid L^?1 day^?1) and pH 7 (407?±?5.5 mg biomass L^?1 day^?1 and 99?±?17.2 mg lipid L^?1 day^?1) for T. suecica CS-187 and Chlorella sp, respectively. In general, biomass and lipid productivities were pH 7.5?>?pH 7?>?pH 8?>?pH 6.5 and pH 7?>?pH 7.5?=?pH 8?>?pH 6.5?>?pH 6?>?pH 5.5 for T. suecica CS-187 and Chlorella sp, respectively. The effect of various inorganic carbon on growth and productivities of T. suecica (regulated at pH?=?7.5) and Chlorella sp (regulated at pH?=?7) grown in bag photobioreactors was also examined outdoor at the International Power Hazelwood, Gippsland, Victoria, Australia. The highest biomass and lipid productivities of T. suecica (51.45?±?2.67 mg biomass L^?1 day^?1 and 14.8?±?2.46 mg lipid L^?1 day^?1) and Chlorella sp (60.00?±?2.4 mg biomass L^?1 day^?1 and 13.70?±?1.35 mg lipid L^?1 day^?1) were achieved when grown using CO₂ as inorganic carbon source. No significant differences were found between CO₂ and flue gas biomass and lipid productivities. While grown using CO₂ and flue gas, biomass productivities were 10, 13 and 18 %, and 7, 14 and 19 % higher than NaHCO₃, HCl and unregulated pH for T. suecica and Chlorella sp, respectively. Addition of inorganic carbon increased specific growth rate and lipid content but reduced biomass yield and cell weight of T. suecica. Addition of inorganic carbon increased yield but did not change specific growth rate, cell weight or content of the cell weight of Chlorella sp. Both strains showed significantly higher maximum quantum yield (F_v/F_m) when grown under optimum pH.     

Molluscan grazing and macroalgal zonation on a rocky intertidal platform at Perth,Western Australia

Abstract Intertidal limestone platforms off Perth show a characteristic pattern of algal zonation, with dense macroalgal beds nearshore bounded by a ‘barren zone’ along the seaward edge. Abalone (Haliotis roei) and several species of limpets and chitons are abundant in the barren zone, which is generally devoid of non-coralline macroalgae. The relative importance of abalone versus limpets and chitons in limiting macroalgal abundance in the barren zone was evaluated by manipulating the presence of each group in a factorial experiment. Percentage algal cover was measured photographically in 0.25m² plots at 1–2 month intervals for 9 months. Mean algal cover (mainly the foliose green alga, Ulva rigida) was highest in plots where all grazers were excluded (77–99%), intermediate where only limpets and chitons were excluded (37–85%), and lowest where only abalone were excluded (4–30%) or where no grazers were excluded (2–19%). The effect of limpets and chitons accounted for 55–89% of the variance in total algal cover, whereas the effect of abalone generally accounted for <10% of the variance. Similar results were obtained in terms of the biomass of Ulva rigida at the end of the experiment. Haliotis roei are relatively large and sedentary herbivores, feeding mainly on drift algae. Their effect on algal abundance was mediated both through pre-emption of space, which might otherwise be colonized by algae, and by grazing around their home scar. Limpets and chitons are smaller than abalone, but were much more abundant. Intensive grazing of the reef surface by limpets and chitons precluded the establishment of non-coralline macroalgae, even where abalone were absent.     

Effects of nutrient enrichment and biochemical composition of diets of Palmaria mollis on growth and condition of Japanese abalone, Haliotis discus hannai and red abalone, Haliotis rufescens

Two growth experiments were conducted with juvenile red abalone, Haliotis rufescens and Japanese abalone, Haliotis discus hannai. The first experiment was set up to determine if nutrient levels used for co-culture of the Rhodophyte, Pacific dulse (Palmaria mollis) directly affected abalone growth. No significant differences (ANOVA; P=0.117) were found in growth of abalone cultured in either ambient seawater alone or seawater supplemented with different NaNO₃ loads (1176, 1765, 2353, and 2942 μM day⁻¹ NO₃-N), NaH₂PO₄ (83.3 μM day⁻¹ PO₄⁻), and a modified version of Guillard and Ryther's [Gran. Can. J. Microbiol. 8, (1962) 229] f medium containing Fe, Zn, Mn, Cu, Mo, and Co.The second experiment was designed to determine the effect of different nutrient levels on the nutritional value of P. mollis when fed to abalone. P. mollis was cultured with different NaNO₃ loads (1176, 1765, 2353, and 2942 μM day⁻¹ NO₃-N) and NaH₂PO₄ (83.3 μM day⁻¹ PO₄⁻) in the presence or absence of f medium trace metals (Fe, Zn, Mn, Cu, Mo, and Co). H. discus hannai showed the highest LGR and SGR when fed on P. mollis supplemented with nitrate loads ranging from 1176 to 2353 μM day⁻¹ NO₃-N. In contrast, H. rufescens showed the highest linear growth rate (LGR) when fed on P. mollis supplemented with higher nitrate loads of 2353 to 2942 μM day⁻¹ NO₃-N, while nitrate load had no significant effect on specific growth rate (SGR). Both abalone species grew better on P. mollis supplied with 0.75f+Zn (day⁻¹) metal solution [Gran. Can. J. Microbiol. 8 (1962) 229] compared to those without trace metal additions, with H. discus hannai showing a further improvement in food conversion efficiencies (FCE).The present work shows that understanding and manipulating the culture environment of P. mollis can significantly affect growth, FCE, and daily food consumption (DFC) of H. discus hannai and H. rufescens.     

Eisenia arborea J.E. Areschoug as abalone diet on an IMTA farm in Baja California,México

Recent progress in the domestication of Eisenia arborea lead us to test this species as an alternative to feed red abalone (Haliotis rufescens) instead of Macrocystis pyrifera, which is the main seaweed used to feed farmed abalone in Baja California, Mexico. E. arborea is the kelp with the largest and most southerly latitudinal distribution on the North Pacific East Coast capable of growing at higher temperatures and in relatively low nutrient conditions. The availability of M. pyrifera is frequently uncertain because it is strongly affected by El Niño events. In order to test E. arborea as a diet for farmed abalone, animals of two different sizes (6 and 2 cm) were fed separately for 12 months with these two seaweed species. The abalones were cultured in cages in an integrated multi-trophic aquaculture farm within San Quintín Bay, Baja California, Mexico. Seaweed was collected for chemical analysis, and every 3 months, animals were measured and weighed to estimate growth. Small size abalone doubled their size on both diets, with an average increase in length of 2.2 mm month^?1. No significant differences were observed between both treatments. Large abalone fed with M. pyrifera had slighter higher growth rates compared to those fed with E. arborea (0.57 and 0.50 % day^?1, respectively). Although M. pyrifera appeared to be a better diet for large animals, the growth rates obtained with E. arborea and the fact that this species could be cultivated in warmer conditions makes this seaweed species a good candidate to feed farmed abalone.     

Cultivation of the two perennial brown algae Ecklonia cava and E. stolonifera for abalone feeds in Korea

Ecklonia cava and Ecklonia stolonifera are perennial brown algae that form sea forests off the coast of Korea. Both species are cultured to supply a summer feed for the abalone industry. Recent expansion of the abalone industry in Korea has been bringing an increase in demand for fresh algal supply. Zoospores of the two algae were seeded in October 2006 on seed frames coiled with 100 m of seed fibers. After 2 months of indoor culture and 2 months of intermediate culture, growth and production of the two algae were compared during their main cultivation period from March 2007 to June 2008, in the culture ground in Wando, Korea (34°26′18.68″ N, 127°05′43.88″ E), in situ. Growth rate of E. cava and E. stolonifera was 1.058 and 3.089 mm day^?1, respectively. The mean production of E. stolonifera obtained from the culture ropes was ca. 12 kg wet wt. m^?1 of culture rope while production of E. cava was ca. 3 kg wet wt. m^?1 of culture rope. The difference in production was attributed from the different growth strategies of the two algae, with only E. stolonifera being able to regenerate blades from the holdfast. The ability to regenerate blades from the holdfast therefore makes E. stolonifera the preferred species for biomass production for abalone feeds. In a 120-day feeding experiment, growth rate, weight gain, and survival rate of abalone showed that E. cava and E. stolonifera feeds could provide an alternative feed to Saccharina japonica during summer months.     

The effect of nutrient concentrations,nutrient ratios and temperature on photosynthesis and nutrient uptake by Ulva prolifera: implications for the explosion in green tides

The green-tide macroalga, Ulva prolifera, was tested in the laboratory to determine its nutrient uptake and photosynthesis under different conditions. In the nutrient concentration experiments U. prolifera showed a saturated uptake for nitrate but an escalating uptake in the tested range for phosphorus. Both N/P and NO₃ ^?/NH₄ ⁺ ratios influenced nutrient uptake significantly (p?<?0.05) while the PSII quantum yield [Y(II)] (p?>?0.05) remained unaffected. The maximum N uptake rate (33.9?±?0.8 μmol g^?1 DW h^?1) and P uptake rate (11.1?±?4.7) was detected at N/P ratios of 7.5 and 2.2, respectively. U. prolifera preferred NH₄ ⁺-N to NO₃ ^?-N when the NO₃ ^?-N/NH₄ ⁺-N ratio was less than 2.2 (p?<?0.05). But between ratios of 2.2 and 12.9, the uptake of NO₃ ^?-N surpassed that of NH₄ ⁺-N. In the temperature experiments, the highest N uptake rate and [Y(II)] were observed at 20 °C, while the lowest rates were detected at 5 °C. P uptake rates were correlated with increasing temperature.     

Methods of improving the utilization of cereal straw by ruminants. II. Further studies on dried grass as a supplement for lambs

Sixteen growing castrated lambs (37.0 ± 3.31 kg) were used in two 5 × 5 and one 6 × 6 Latin squares to measure the intake and digestibility of: (1) urea—molasses-treated straw, or mixtures containing (2) 25; (3) 50; or (4) 75% dried grass; and (5) grass alone. The dry matter intake was 40, 50, 69, 84 and 90 g day^?1 per kg of metabolic live weight (P<0.001), and digestibility was 470, 489, 591, 671 and 735 g kg^?1, respectively, for the above treatments. The dry matter intake of lambs offered diets 2, 3 and 4 as complete diets was 47, 56 and 66 g day^?1 kg of metabolic live weight, and digestibility was 513, 621 and 673 g kg^?1, respectively. When the feeds were offered separately, dry matter intake was 54, 63 and 78 g day^?1 per kg of metabolic live weight and digestibility was 541, 582 and 662 g kg^?1, respectively. Dry matter intake for mixed diets was higher (P<0.01) than for feeds given separately.     

Accumulation of phlorotannins in the abalone Haliotis discus hannai after feeding the brown seaweed Ecklonia cava

Value-added abalone Haliotis discus hannai containing bioactive phlorotannins is produced by simply changing the feed to phlorotannin-rich brown seaweed Ecklonia cava 2 weeks prior to harvesting. We assessed the accumulation of phlorotannins by feeding with the seaweed after 4 days of starvation. Reverse-phase high-performance liquid chromatography afforded isolation of the major phlorotannins, which were identified by mass spectrometry and ¹H-nuclear magnetic resonance to be 7-phloroeckol and eckol. Throughout the E. cava feeding period of 20 days, 7-phloroeckolol accumulated in the flesh (foot muscle tissue), up to 0.85?±?0.21 mg g^?1 dry weight of tissue after 12 days. Eckol reached 0.31?±?0.08 mg g^?1 dry tissue after 14 days. Feeding Laminaria japonica as a control, we detected no phlorotannins in the abalone muscle tissue. Abalone seaweed consumption and growth rate were similar when fed with E. cava or L. japonica for 20 days. Reduction in phlorotannins to half-maximal accumulation took 1.0 and 2.7 days for 7-phloroeckol and eckol, respectively, after replacement of the feed with L. japonica.     

Effects of the dietary administration of sodium alginate on the immune responses and disease resistance of Taiwan abalone,Haliotis diversicolor supertexta

Sodium alginate extracted from brown algae was reported to enhance the immune response and resistance of fish and shrimp. In this study, survival rates of the abalone, Haliotis diversicolor supertexta, against Vibrio parahaemolyticus, and its non-specific immune parameters such as the total haemocyte count (THC), phenoloxidase (PO) activity, respiratory bursts, superoxide dismutase (SOD) activity, phagocytic activity, and clearance efficiency to V. parahaemolyticus by H. diversicolor supertexta were determined when abalone (4.5 ± 0.4 g) were fed diets containing sodium alginate at 0, 1.0, 2.0, and 3.0 g kg^?1. Abalone fed a diet containing sodium alginate at 2.0 and 3.0 g kg^?1 for 14 days and at 1.0 g kg^?1 for 21 days had significantly higher survival rates than those fed the control diet after challenge with V. parahaemolyticus. The relative survival percentages of abalone fed the 1.0, 2.0, and 3.0 g kg^?1 sodium alginate-containing diets for 14 and 21 days were 16.1%, 40.0%, and 48.0%, and 63.6%, 27.3% and 22.6%, respectively. The PO activity, respiratory bursts, SOD activity, and phagocytic activity and clearance efficiency of V. parahaemolyticus of abalone fed the sodium alginate-containing diets at 1.0, 2.0, and 3.0 g kg^?1 were significantly higher than those of abalone fed the control diet for 14 days. After 21 days, the PO activity, respiratory bursts, SOD activity, and phagocytic activity and clearance efficiency of V. parahaemolyticus by abalone fed the sodium alginate-containing diet at 1.0 g kg^?1 were significantly higher than those of abalone fed the other diets. It was concluded that sodium alginate can be used as an immunostimulant for abalone through dietary administration to enhance immune responses of abalone and resistance against V. parahaemolyticus, which were related to the dose and timing of administration.     

Effectiveness of Maifanite in Reducing the Detrimental Effects of Cadmium on Growth Performance, Cadmium Residue, Hematological Parameters, Serum Biochemistry, and the Activities of Antioxidant Enzymes in Pigs

This study was conducted to investigate the toxicity of cadmium and to evaluate the effectiveness of maifanite in preventing cadmium-induced adverse effects. Thirty-two crossbred pigs (Duroc × Landrace × Large white, sex balanced, 17.25?±?0.07 kg average body weight) were randomly allotted to one of four dietary treatments in a 2?×?2 factorial arrangement, with eight replicates per treatment and one pig per replicate. The dietary treatments included two cadmium (as CdCl₂) doses (0.32 and 30.49 mg/kg) and two maifanite doses (0 and 1 %). The results showed that pigs treated with cadmium decreased their average daily feed intake (P?<?0.05) and increased (P?<?0.05) the feed/gain ratio. Cadmium was found in the tissues of pigs that were fed with cadmium-contaminated diets, but the level of cadmium was much lower when maifanite was added to the cadmium-contaminated diets. Ingestion of diets that were artificially contaminated with cadmium (30.49 mg/kg of cadmium) reduced (P?<?0.05) the number of lymphocytes, the total erythrocyte count, the hemoglobin level, and the hematocrit. However, the activities of serum aspartate aminotransferase and gamma glutamyltransferase were increased (P?<?0.05). The total protein level was lower (P?<?0.05) in pigs fed with cadmium-contaminated diets. The contents of malondialdehyde increased (P?<?0.05), while the total antioxidant capacity and the activities of total superoxide dismutase, glutathione peroxidase, glutathione S-transferase, and catalase decreased (P?<?0.05) in pigs fed with cadmium-contaminated diets. Dietary addition of maifanite can, to some extent, prevent the negative effects associated with feeding cadmium diets (30.49 mg/kg of cadmium) to pigs.     

Effects of Iron Glycine Chelate on Growth, Tissue Mineral Concentrations, Fecal Mineral Excretion, and Liver Antioxidant Enzyme Activities in Broilers

The study was conducted to determine the effects of iron glycine chelate (Fe-Gly) on growth, tissue mineral concentrations, fecal mineral excretion, and liver antioxidant enzyme activities in broilers. A total of 360 1-day-old commercial broilers (Ross?×?Ross) were randomly allotted to six dietary treatments with six replications of ten chicks per replicate. Broilers were fed a control diet with no Fe supplementation, while five other treatments consisted of 40, 80, 120, and 160?mg Fe/kg diets from Fe-Gly, and 160?mg Fe/kg from ferrous sulfate, respectively. After a 42-day feeding trial, the results showed that 120 and 160?mg Fe/kg as Fe-Gly improved the average daily gain (P?<?0.05) and average daily feed intake (P?<?0.05) of broilers (4?C6?weeks). Addition with 120 and 160?mg Fe/kg from Fe-Gly and 160?mg Fe/kg from FeSO₄ increased Fe concentration in serum (P?<?0.05), liver (P?<?0.05), breast muscle (P?<?0.05), tibia (P?<?0.05), and feces (P?<?0.01) at 21 and 42?days. There were linear responses to the addition of Fe-Gly from 0 to 160?mg/kg Fe on Fe concentration in serum (21?days, P?=?0.005; 42?days, P?=?0.001), liver (P?=?0.001), breast muscle (P?=?0.001), tibia (P?=?0.001), and feces (21?days, P?=?0.011; 42?days, P?=?0.032). Liver Cu/Zn superoxide dismutase activities of chicks were increased by the addition of 80, 120, and 160?mg Fe/kg as Fe-Gly to diets at 42?days. There were no differences in liver catalase activities of chicks among the treatments (P?>?0.05). This study indicates that addition with Fe-Gly could improve growth performance and iron tissue storage and improves the antioxidant status of broiler chickens.     

Pterocladia (Rhodophyta) and Ulva (Chlorophyta) as feed supplements for European seabass, Dicentrarchus labrax L., fry

The aim of this study was to evaluate the suitability of two marine macroalgae, Ulva lactuca (Chlorophyta) and Pterocladia capillacea (Rhodophyta), meals as a supplement to enhance the nutritional value of formulated feeds for European seabass Dicentrarchus labrax fry. Seven isoproteic (50 % crude protein), isocaloric (500 Kcal/100 g gross energy) diets containing four levels (0 or control, 5, 10, and 15 %) of either Ulva meal (UM) or Pterocladia meal (PM) were tested. Each diet was fed to triplicate groups of D. labrax fry (initial body weight, 0.23?±?0.02 g for Ulva- and 0.14?±?0.01 g for Pterocladia-fed fish), to apparent visual satiety for 8 weeks. The results indicated that feeding seabass at 5 % UM or PM level (U₅ and P₅ diets) produced the best growth, feed utilization, nutrient retention, and survival rates among all the dietary groups. Feeding fish with a 5 % PM-added diet has also improved stress response after a 5-min air exposure test, prior to the termination of the feeding trial. These findings suggest that both Pterocladia and Ulva meals could be potentially used as an additional feed component (at 5 %) for enhancement of seabass D. labrax fry performance, nutrients composition, and stress resistance especially when subjected to transportation from hatchery to weaning ponds/tanks.     

Short Communication

Abalone farmed in Australia are predominantly fed formulated feeds, while in the wild, their diet consists of a mix of macroalgae. Here we investigated the feeding behaviour of juvenile greenlip abalone, Haliotis laevigata; fed live macroalgae and formulated diets at different rations; and observed their feeding behaviour using a novel ventral video monitoring technique. Four different diets (commercial chip, experimental flake, Ulva sp. and Gracilaria cliftonii) at two feeding rations (excess vs. restricted) were tested. Diet type had no effect on abalone movement, but macroalgal diets resulted in higher feed intakes. Restricting feed rations induced greater movement. Abalone moved little during the light period and moved mostly during darkness, except for animals on the restricted feed ration where feeding commenced during the light period. On farms, this phenomenon may be a useful behavioural indicator for identifying underfed abalone. Despite their lower intake, formulated diets promoted higher energy and nutritional intake, indicating that quantity of feed consumed is not solely indicative of nutritional gain. From a research perspective, the novel ventral monitoring method has created opportunities for further behavioural studies in molluscs.     

Effects of wild and farm-grown macroalgae on the growth of juvenile South African abalone Haliotis midae Linnaeus

The effect of various macroalgal diets on the growth of grow-out (>20 mm shell length) South African abalone Haliotis midae was investigated on a commercial abalone farm. The experiment consisted of four treatments: fresh kelp blades (Ecklonia maxima (Osbeck) Papenfuss) (c. 10% protein); farmed, protein-enriched Ulva lactuca Linnaeus (c. 26% protein) grown in aquaculture effluent; wild U. lactuca (c. 20% protein); and a combination diet of kelp blades + farmed U. lactuca. Abalone grew best on the combination diet (0.423 ± 0.02% weight d^?1 SGR [specific growth rate]; 59.593 ± 0.02 ?m d^?1 DISL [daily increment in shell length]; 1.093 final CF [condition factor]) followed by the kelp only diet (0.367 ± 0.02% weight d^?1 SGR; 53.148 ± 0.02 ?m d^?1 DISL; 1.047 final CF), then the farmed, protein-enriched U. lactuca only diet (0.290 ± 0.02% weight d^?1 SGR; 42.988 ± 0.03 um d”¹ DISL; 1.013 final CF) that in turn outperformed the wild U. lactuca only diet (-0.079 ± 0.01% weight d^?1 SGR; 3.745 ± 0.02 ?m d”^?1 DISL; 0.812 final CF). The results suggest that protein alone could not have accounted for the differences produced by the varieties of U. lactuca and that the gross energy content is probably important.     

Comparison of growth and lipid composition in the green abalone, Haliotis fulgens, provided specific macroalgal diets

Lipid composition of abalone was examined over a one-year interval. A feeding trial was designed to cover a full reproductive cycle in young adult green abalone, Haliotis fulgens, consisting of five diet treatments: the macrophytic algal phaeophyte Egregia menziesii, rhodophyte Chondracanthus canaliculatus, chlorophyte Ulva lobata, a composite of the three algae and a starvation control. The lipid class, fatty acid, sterol and 1-O-alkyl glyceryl ether profiles were determined for foot, hepatopancreas/gonad tissues and larvae. The major fatty acids were 16:0, 18:0, 18:1(n-7)c, 18:1(n-9)c, 20:4(n-6), 20:5(n-3) and 22:5(n-3), as well as 14:0 for abalone fed brown and red algae. 4,8,12-Trimethyltridecanoic acid, derived from algae, was detected for the first time in H. fulgens (hepatopancreas complex, 1.2–13.9%; larvae, 0.5% of total fatty acids). Diacylglyceryl ethers were present in larvae (0.6% of total lipid). The major 1-O-alkyl glycerols were 16:0, 16:1 and 18:0. Additionally, 18:1(n-9) was a major component in hepatopancreas/gonad and larvae. The major sterol was cholesterol (96–100% of total sterols). Highest growth rates were linked to temperature and occurred in abalone fed the phaeophyte E. menziesii (43 μm·day^–1, 56 mg·day^–1 yearly mean), an alga containing the highest levels of C₂₀ polyunsaturated fatty acids and the highest ratio of 20:4(n-6) to 20:5(n-3). This study provides evidence of the influence of diet and temperature on seasonal changes in abalone lipid profiles, where diet is most strongly related to body mass and temperature to shell length. The allocation of lipids to specific tissues in green abalone clarifies their lipid metabolism. These results provide a basis for improving nutrition of abalone in mariculture through formulation of artificial feeds.     

Lack of Effect of Dietary Chromium Supplementation on Growth Performance and Serum Insulin, Glucose, and Lipoprotein Levels in Broilers Reared Under Heat Stress Condition

This study evaluated the effects of supplemental dietary chromium (Cr) on the performance, carcass traits, and some serum parameters of broilers under a heat stress (23.9 to 37 °C cycling) condition. A total of 150 1-day-old broiler chicks (Cobb 500) according to a completely randomized design were assigned into five treatment groups. Each treatment consisted of three replicates and each replicate contained ten chicks. Treatments were supplemented with 0 (control), 600, and 1,200 μg kg^?1 Cr in the form of Cr chloride (CrCl₃) and Cr L-methionine from 1 to 49 days of age. Blood samples were collected from two birds in each replicate to determine serum parameters at 35 and 49 days of age. The body mass, feed intake, and conversion ratio were not influenced by dietary Cr (P?>?0.05). Dietary supplementation of Cr from either CrCl₃ or Cr L-methionine caused increased serum concentrations of Cr (P?<?0.05), but had no effect on serum insulin and glucose concentrations at both sampling times (P?>?0.05). Serum triglycerides, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were also not significantly affected (P?>?0.05) by dietary treatments, whereas total cholesterol concentration decreased in chicks fed Cr L-methionine compared to the control (P?<?0.05).     

Effect of Seawater–Sewage Cross-Transplants on Bacterial Metabolism and Diversity

Bioassays experiments were conducted to determine the metabolic and community composition response of bacteria to transplants between relatively pristine coastal seawater and sewage-impacted seawater. There were four treatments: (1) pristine seawater bacteria?+?pristine seawater (Pb?+?Pw), (2) sewage-impacted bacteria?+?sewage-impacted water (Sb?+?Sw), (3) pristine seawater bacteria?+?sewage-impacted water (Pb?+?Sw), and (4) sewage-impacted bacteria?+?pristine seawater (Sb?+?Pw). Sewage-derived DOC was more labile and readily utilized by bacteria, which favored the growth of high nucleic acid (HNA) bacteria, resulting in high bacterial production (BP, 113?±?4.92 to 130?±?15.8 μg C l^?1?day^?1) and low respiration rate (BR, <67?±?11.3 μg C l^?1?day^?1), as well as high bacterial growth efficiency (BGE, 0.68?±?0.09 to 0.71?±?0.05). In contrast, at the relatively pristine site, bacteria utilized natural marine-derived dissolved organic matter (DOM) at the expense of lowering their growth efficiency (BGE, <0.32?±?0.02) with low BP (<62?±?6.3 μg C l^?1?day^?1) and high BR 133?±?14.2 μg C l^?1?day^?1). Sewage DOM input appeared to alter the partitioning of carbon between respiration and production of bacteria, resulting in a shift toward higher BGE, which would not enhance oxygen consumption. Taxonomic classification based on 454 pyrosequencing reads of the 16S rRNA gene amplicons revealed that changes in bacterial community structure occurred when seawater bacteria were transferred to the eutrophic sewage-impacted water. Sewage DOM fueled the growth of Gammma-proteobacteria and Epsilson-proteobacteria and reduced the bacterial richness, but the changes in the community were not apparent when sewage-impacted bacteria were transferred to pristine seawater.