Comparison of taste components in cooked meats of small abalone fed different diets

ABSTRACT: Differences in taste preference and the levels of extractive components and glycogen were compared between cooked meats of small abalone Haliotis diversicolor fed either gracilar (G-small abalone) or an artificial diet (A-small abalone). Using sensory tests, taste preference of cooked meats was significantly higher for A-small abalone than for G-small abalone. Results of clustering analysis and principal component analysis of chemical data also revealed that the two cooked meats differed from each other in terms of their measured constituent compositions irrespective of sampling periods. Compared with G-small abalone, A-small abalone meats were lower in taurine and arginine, but higher in glycine (Gly), glutamic acid (Glu), alanine, serine, proline, adenosine monophosphate (AMP), and glycogen. It is concluded that the discrepancy in the levels of taste-active components of abalone, such as Gly, Glu, and AMP, is likely to be responsible for the differences in taste preference between G- and A-small abalone cooked meats.     

Growth and survival of three small abalone Haliotis diversicolor populations and their reciprocal crosses

The aquaculture industry of small abalone Haliotis diversicolor in southern China is now close to collapse because of high mortality at the grow-out stage. To examine if survival and growth (shell length increase) could be improved by cross breeding among populations, a 3 × 3 complete diallel cross was conducted among three populations from Japan (A), Taiwan (B) and Vietnam (C). Performances in growth rate and survival at early juvenile, later juvenile and grow-out stages were compared among the six reciprocal cross lines and three parental lines. Magnitude of heterosis for survival and growth varied among cross lines in the three growing stages. As to mid-parent heterosis, H _AB was significantly ( P <0.01) higher than H _AC and H _BC at all three growing stages for both growth and survival, and all mid-parent heterosis fell between the two corresponding single-parent heterosis. H _AB was 6.84% for shell length and 69.09% for survival at Day 420. Our results of high survival heterosis in line AB and line BA show that crossbreeding between different populations can benefit the small abalone breeding programs and the industry.     

Seasonal variations of chemical constituents in the muscle and viscera of small abalone fed different diets

SUMMARY: The seasonal changes in levels of chemical constituents in the muscle and viscera of small abalone Haliotis diversicolor fed gracilar and an artificial diet were investigated. Muscle yields were higher in winter and spring. In October specimens, total adenosine 5'-triphosphate (ATP)-related compounds (ARC), total free amino acids (FAA), and glycogen in both muscle and viscera decreased markedly. The artificial diet fed to small abalone had much higher glycogen in the muscle than those fed on gracilar, and showed a great seasonal change. Total amounts of ARC in the muscles were higher through March to July, while those in the viscera were maximal in January. Taurine, arginine, glycine, glutamic acid, and alanine were the major FAA in both tissues, accounting for 81–94% of the total FAA. Total amounts of FAA in the muscles were higher in the samples collected from winter and early spring than in other seasons. Glycine, glutamic acid, and adenosine monophosphate might be the most important taste components related to the palatability of small abalone. Their total amounts in the muscles of the two specimens were considerably high in December to March. This finding suggested that small abalone produced in winter and early spring might be more palatable.     

杂色鲍幼苗大规模死亡与细菌数量的关系

对杂色鲍育苗过程中养殖池、附着板上的细菌数量进行了监测,当鲍苗出现大规模死亡前后,池水及附着板上细菌数量比养殖初期高2个数量级,利用臭氧处理养殖水后,附着板上的细菌数量没有发生根本变化,鲍苗同样出现死亡,鲍苗剥离后1周左右也出现大规模死亡。在鲍苗大规模死亡前后分离的细菌经过鉴定为塔式弧菌及Vibrio sp.     

Growth of the abalone Haliotis diversicolor (Reeve) fed with macroalgae in floating net cage and plastic tank

The abalone Haliotis diversicolor (Reeve) or ‘tokobushi’ is being cultured in Kagoshima, southern Japan for stock enhancement of fishing grounds. However, with decreasing catches from the wild some fishermen's group may eventually resort to rearing tokobushi until of marketable size. Growth experiments of tokobushi fed macroalgae in floating net cage and plastic tanks were conducted to evaluate the influence of culture system, macroalgal food, age and water temperature on their culture. In floating net cage, marketable sizes were obtained at the age of 457–822‐day old (15–27‐month old) with highest growth rate of 2.36% g day^?1 and 0.21 mm day^?1. One advantage of the plastic tank culture system was that the tokobushi shell remained clean throughout the culture period. Macroalgal food affected the growth rate; Sargassum fusiforme (Setchell)‐ and Ulva pertusa (Kjellman)‐fed tokobushi were better than Meristotheca papulosa (Montagne)‐fed. Further, 1‐year‐old tokobushi had better growth performance and condition index than the 2‐year‐old cohort, and growth rates were higher at 17°C than at 12°C. These findings should help tokobushi farmers design their mariculture scheme considering both economic and environmental aspects.     

Identification of juvenile abalone <Emphasis Type="Italic">Haliotis diversicolor</Emphasis> based on number of open and sealed respiratory pores

ABSTRACT:   Changes in the number of respiratory pores (open pores) and their imprints (sealed pores) in post-larvae and juveniles were observed and compared for four abalone species Haliotis diversicolor , H. discus discus , H. madaka , and H. gigantea . The first open pore was evident at a shell length (SL) of 1.5 mm in H. diversicolor , 1.9–2.0 mm SL in H. discus discus , and 2.3–2.4 mm SL in H. madaka and H. gigantea . The number of open pores in H. diversicolor gradually increased with growth, with four to five pores at 2.5–18.0 mm SL and five to six pores at 18.0–27.0 mm SL. The other three species maintained four to five open pores after they reached 3.4–4.5 mm SL. The total number of open and sealed pores (TNP) was greater in H. diversicolor than in the other species at the same SL. Juvenile H. diversicolor were identified among field-caught abalone by the difference in the relationship between SL and TNP (SL–TNP relationship) and also by the monoclonal antibody reaction method. The results of the two methods were in perfect agreement, indicating that our method using the SL–TNP relationship is reliable for the identification of H. diversicolor .     

An assessment of the efficacy of two lysine microencapsulation techniques to determine the quantitative lysine requirement of the South African abalone, Haliotis midae L.

The quantification of the essential amino acid requirements of a species is a prerequisite to the formulation of biologically optimized diets. In this study, crystalline L -lysine was used in an attempt to determine the quantitative lysine requirement of juvenile Haliotis midae . Two microencapsulation techniques [gelatine/acacia and cellulose acetate phthalate (CAP)] were used to retard leaching of crystalline L -lysine incorporated into semipurified test diets. An assessment of the efficacy of the encapsulation techniques, revealed that despite effective lysine supplementation, H. midae fed semipurified test diets containing encapsulated crystalline L -lysine failed to promote significant improvements in either growth, feed or protein efficiency ( P  > 0.05). The failure of the crystalline L -lysine to illicit growth and nutritional responses is discussed.     

九孔鲍幼鲍生长性状的遗传参数估计

采用不平衡巢式设计方法和人工授精技术,1个父本配3个母本,建立九孔鲍(Haliotis diversicolor super-texta)12个半同胞家系和36个全同胞家系.在40日龄、120日龄、180日龄、240日龄时分别对所建36家系个体测量壳长,壳宽与体质量.采用单性状约束最大似然法(Restricted Maximum Likelihood Method, REML)估计九孔鲍(Haliotis diversicolor supertexta)各阶段体质量,壳宽与壳长性状的遗传参数.结果表明,九孔鲍幼鲍在40、120、180、240日龄时壳长遗传力估计值为(0.13±0.09)~(0.56±0.15),壳宽遗传力估计值为(0.13±0.06)~(0.62±0.13),体质量遗传力估计值为(0.18±0.15)~(0.26±0.08),均属于中等遗传力.另外,从性状的表型相关与遗传相关可以得出,九孔鲍稚鲍在不同日龄壳长、壳宽与体质量的表型相关和遗传相关均为正相关(P≤0.05).表型相关系数为0.66~0.94,遗传相关系数为0.85~0.98,研究结果表明,以3个主要生长性状之一作为选育目标,均能达到遗传改良的目的.     

Changes in taste and textural properties of the foot of the Japanese cockle (Fulvia mutica) by cooking and during storage

Physicochemical changes of Japanese cockle foot parts occurring during cooking and cold storage at 4°C for 10 days were examined. Raw samples decreased in weight by 27% during cooking at 85°C for 15 s. Both raw and cooked samples decreased in weight to the same extent of 22–23% during the 10-day cold storage. The levels of ATP and related compounds, as well as those of free amino acids, were higher in raw than in cooked samples, although the former were found by sensory evaluation to have a stronger fishy odor. Raw samples started to decrease in ATP content after 5 days of cold storage, showing K' values of 18 and 42% after 5 and 7 days, respectively. The L* value in the Hunter scale color evaluation increased during the cold storage of raw samples, revealing a gradual disappearance of its original purple–gray color. Meanwhile, the L* value of cooked samples remained constant during the cold storage. The tensile strength of cooked samples was significantly higher than those of both raw samples before and after the cold storage, indicating increased toughness by cooking.     

Extractive component changes in the foot muscle of live small abalone during storage

ABSTRACT: Changes in the freshness indices and extractive components in the foot muscle of live small abalone Haliotis diversicolor during storage at 5°C, 15°C, and 25°C were investigated. The pH values declined with storage time. Volatile basic nitrogen and the K -value increased gradually with storage time at 15°C and 25°C, but changes were small at 5°C. The onset of initial decomposition of samples was observed after 3.5 days at 5°C, after 2.5 days at 15°C, and after one day at 25°C. Adenosine triphosphate and adenosine diphosphate degraded rapidly within the early days of storage. In contrast, levels of adenosine monophosphate increased and exhibited prolonged accumulation throughout the storage period. The total amount of free amino acids increased markedly during storage. The dominant free amino acids, such as taurine, glutamic acid, glycine, alanine, and arginine, also increased after storage.     

Community and trophic structures of abalone <Emphasis Type="Italic">Haliotis diversicolor</Emphasis> habitat in Sagami Bay,Japan

Abstract:   The community and trophic structures of the subtidal habitat of the abalone Haliotis diversicolor were examined in Nagai, Sagami Bay, Japan. Conventional community indices showed no significant differences among three sampling stations. The overall continuum of stable isotope ratios was structured into three different trophic linkages: (i) brown algae-dependent benthic food chain; (ii) red algae-dependent benthic food chain; and (iii) planktonic food chain. Brown algae and red algae likely play different roles with respect to carbon sources in the habitat. Conventional fractionation values indicated that the abalone H. diversicolor (δ¹³C = −12.4 ± 1.0‰, δ¹⁵N = 9.3 ± 0.5‰) feeds on the lamina of Undaria pinnatifida during juvenile and adult stages (8.0–65.6 mm shell length). Stable isotope signatures suggested that the juveniles of other abalone species as well as some amphipods and a sea cucumber Holothuria decorata are competitors of H. diversicolor , whereas some Muricidae gastropods such as Thais bronni and Ergalatax contractus are predators. The isotopic differences among macroalgal species and the subsequent transfer to consumers indicate that stable isotopic analysis is an effective means of studying food webs in an open rocky shore community with little influence from external primary production such as terrestrial vegetation.     

Effects of oxygen supersaturation and temperature on juvenile greenlip, Haliotis laevigata Donovan, and blacklip, Haliotis rubra Leach, abalone

Growth and survival of juvenile greenlip (39.03 (SD 3.80) mm (n=524)) and blacklip (31.92 (SD 4.19) mm (n=531) abalone were investigated at high dissolved oxygen levels (95–120% saturation) between 17 and 19°C. Abalone were fed the same artificial diet and each species was contained in groups of approximately 30 individuals within triplicate tanks for each of six treatments and were exposed to flow through water adjusted to give experimental conditions for up to 75 days. Blacklip abalone held at 16.9°C and 97% oxygen saturation grew in shell length significantly faster than all other treatments of blacklip abalone held at 19°C, and significantly faster than blacklip abalone maintained at 111% oxygen saturation and 17.5°C. Both temperature and oxygen saturation significantly affected the survival of this species. Blacklip abalone held at 19°C had significantly lower survival for both 96% oxygen saturation and 120% oxygen saturation, compared with blacklip abalone maintained at either 110% oxygen saturation and 19°C, or for any 17°C treatment. No significant differences were noted for greenlip abalone within the range tested in terms of growth rate, food consumption rate or survival, indicating that greenlip abalone tolerated these conditions better than did blacklip abalone.     

Growth and reproductive performance of triploid and diploid blacklip abalone, Haliotis rubra (Leach, 1814)

Growth and reproduction of triploid and diploid blacklip abalone Haliotis rubra (Leach, 1814) were compared in a 30-month study. Triploidy was induced by inhibition of the second polar body formation using 6-dimethylaminopurine (6-DMAP) or cytochalasin B (CB). There were no significant differences in growth and survivorship between triploid and diploid abalone. However, triploid abalone had a more elongated shell and greater foot muscles than diploid abalone. A slightly curvilinear growth in shell length was conformed to all treatments. While diploid abalone had reached sexual maturity and spawned during the study, gonadal development and gamete maturation were abnormal in triploids. Female triploids lacked an apparent gonad at the macroscopic level but microscopic examination revealed that they had a thin layer of oogonia development. In contrast, male triploids were able to form similar-sized gonads to diploids during most of the reproductive period, but with brown-yellow discolouration and stalled gametogenesis at spermatocyte formation. Sex ratio of triploid abalone did not deviate from 1:1. With the onset of sexual maturation, growth and gonadal maturation occurred concurrently in diploid abalone, and there was no indication that growth of (diploid) abalone was reduced.     

光照强度对九孔鲍幼虫及幼鲍生长存活的影响

在自然光周期下，分别在高温长光照和低温短光照的两个节季节，采用控制光照强度的方法进行对九孔鲍幼虫及幼鲍50d左右培育的小型试验。结果表明，光照强度对附着基上摄食微藻的幼虫及幼鲍生长和存活等有重要的影响。对幼虫及幼鲍最适宜的光照强度，在高温长光照下为700－1200lx，在低温短光照下为1300－2000lx。选用适宜的光照强度在高温长光照和低温短光照下先后进行了3次经量育苗试验，获得了与小型试验相同的结果。     

Effect of dietary protein and temperature on the growth and health of juvenile New Zealand black‐footed abalone (Haliotis iris)

The protein requirements for optimal growth and health of juvenile New Zealand black‐footed abalone (Haliotis iris) under different water temperatures were investigated. Six diets with different crude protein amounts (0, 10, 20, 30, 40 and 45%) and two temperature regimes (13–21 and 8–16 °C) were used to culture juvenile abalone over a 4‐month period. Growth (shell lengths and animal weights) and health (survival, activity and mucous production) parameters were recorded for animals within all protein and temperature combinations. Proximate analyses and amino acid profiles were also performed on the diets, soft bodies (including gonad), and shells to evaluate the overall nutrient contents (diet and animal) and requirements (animal). The results indicate that the protein requirements for juvenile H. iris are higher when the environmental temperatures are low. Thus, increasing the dietary protein level results in better growth [i.e. increase in soft body (including gonad) crude protein and mean protein gain] and health (i.e. more goblet cells and thicker epithelial layers). Results from amino acid profiles in abalone soft bodies (including gonad) and shells show that these parameters did not change considerably with different dietary protein levels, but temperature did affect the concentration of several amino acids in both soft bodies (including gonad) and shells.     

Supplementary oxygen and temperature management during live transportation of greenlip abalone, Haliotis laevigata (Donovan, 1808)

Live greenlip abalone, Haliotis laevigata , are highly valued in Australian export markets with demand increasingly being met with cultured stock. Live transportation of abalone requires the maintenance of favourable conditions within transport containers for periods exceeding 35 h. We examined the combined effects of temperature regulation (ice provision) and of supplemental oxygen (60% and 100% concentrations) on mortality rates of abalone over 7 days following a 35-h simulated live-transport experiment. We also examined the physiological condition of greenlip abalone (oxygen consumption rate, haemolymph pH and weight) during the simulation experiment. The provision of ice and supplementary oxygen reduced abalone mortalities. Omission of ice and supplementary oxygen during the transport simulation resulted in mortality rates ranging from 70% to 100%. The addition of ice to containers with ambient oxygen concentrations decreased average mortality rates by 50%. While supplementary oxygen further reduced these rates, the provision of both ice and 100% oxygen was by far the most effective combination, reducing mortalities to between 2% and 6%. Supplementary oxygen increased oxygen consumption rates of abalone above those transported at ambient oxygen concentrations. Live-transport decreased haemolymph pH in all treatments but was most pronounced in treatments without ice or supplementary oxygen. On average, abalone lost 7–13% of their weight during the simulation but this loss was independent of transport treatment.     

Effects of alternate starvation and refeeding cycles on food consumption and compensatory growth of abalone, Haliotis asinina (Linnaeus)

The effects of alternate starvation and refeeding on food consumption and compensatory growth of hatchery‐bred abalone, Haliotis asinina (Linnaeus), were determined. Two groups of abalone juveniles (mean shell length = 29 mm, body weight = 5 g) were alternately starved and refed a macro‐alga, Gracilariopsis bailinae at equal duration (5/5 or 10/10) over 140 days. A control group (FR) was fed the seaweed ad libitum throughout a 200‐day experimental period. Starved and refed abalone showed slower growth rates (DGR, 63 and 70 mg/day in the 5/5 and 10/10 groups respectively), as a result of reduced food intake (DFI 15% and 16% day^?1 respectively), after repeated starvation and refeeding cycles. Percentage weight gains (5/5 = 196%, 10/10 = 177%) were significantly lower than that of the control (397%). When refed continuously over 60 days, the starved groups exhibited increased DFI and fed at the rate of 24% and 25% day^?1, which were not significantly different from that of the control at 26% day^?1. At the end of the experiment, no significant differences were observed among three treatments in terms of shell length (range: 46–48 mm), body weight (range 25–28 g), % weight gain (392–465%) and per cent survival (range 87–98%). The results indicated that H. asinina had a complete compensatory growth following a return to full rations after a series of intermittent starvation and refeeding cycles.