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.     

Effects of temperature on growth of juvenile blackfoot abalone, Haliotis iris Gmelin

The effects of temperature on growth and survival of juvenile blackfoot abalone, Haliotis iris, were investigated. Animals of 10, 30 or 60 mm initial shell length were exposed to ambient (6–10°C), 14, 18, 22 and 26°C for 112 days in a flow‐through culture system. Maximum growth occurred at 22°C for the 10 and 30 mm size classes and at 18°C for the 60 mm size class. Regression analysis identified the optimal temperature for growth (T_optG) at around 21°C for the 10 and 30 mm size classes and at 17–18°C for the largest size class. In a second experiment, the critical thermal maximum of H. iris was determined as a measure of thermal tolerance. Abalone were subjected to increasing water temperatures at a rate of 2°C h^?1 until they detached from the substrate. Abalone of 10 mm displayed greater thermal tolerance than abalone of 30 and 60 mm in length. CT₅₀ temperatures were 28.8, 27.7 and 27.8°C, yielding deduced T_optG values of 19.7, 18.3 and 18.4°C for the 10, 30 and 60 mm size classes respectively. The size‐dependent nature of the relationship between growth and temperature could be capitalized upon in recirculating aquaculture systems.     

Studies on the Development of Small Abalone (Haliotis diversicolor supertexta) Essence and its Antioxidative Properties

Essences of small abalone (Haliotis diversicolor supertexta) were prepared by two methods, steaming and boiling. The chemical constituents and antioxidative properties of these essences were determined and compared to those of commercial freshwater clam essence (CFCE). Boiled small abalone essence (BSAE) contained more total soluble solids than steamed small abalone essence (SSAE). Total soluble solids and peptide content of both essences increased with longer extraction time. Glycogen contents of SSAE, BSAE, and CFCE were 14.01, 13.95, and 10.74 mg/mL, respectively. The concentrations of free amino acids in SSAE and BSAE (725.05 and 818.56 mg/100 g, respectively) were significantly higher than in CFCE (33.57 mg/100 g). The antioxidative properties of SSAE and BSAE were higher than that of CFCE. The reducing power and ferrous iron (Fe²⁺) chelating activity of 3-h SSAE were significantly higher than those of 10-min BSAE. The predominant free amino acid of both SSAE and BSAE was taurine (227.14–273.64 mg/100 g), followed by proline and arginine. Both essences also showed high correlations between peptide content and Fe²⁺ chelating activity and reducing power. Sensory evaluation trials suggested that 3-h SSAE is more favorable than BSAE in terms of appearance and overall acceptability. In conclusion, SSAE had better antioxidative properties and sensory scores than BSAE.     

诱导皱纹盘鲍浮游幼虫附着和变态的物质

根据鲍育苗中常用的6种底栖硅藻氨基酸的组成分析结果,选择15种人工合成氨基酸作为诱导物质,进行鲍浮游幼虫附着、变态的影响实验,发现天冬氨酸组附着率最高,谷氨酸组次之,但均略低于底栖硅藻组,明显高于对照组。变态率实验,天冬氨酸和谷氨酸组结果基本一致,均略高于底栖硅藻组,明显高于对照组。不同氨基酸浓度对附着、变态的影响实验结果表明:无论是天冬氨酸还是谷氨酸,实验浓度为10-5mol·L-1组的附着率和变态率最高。     

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.     

GABA受体拮抗剂荷包牡丹碱和CGP52432对厚壳贻贝幼虫附着变态的影响

为研究GABA及其受体拮抗剂荷包牡丹碱（GABA_A受体）和CGP52432 （GABA_B受体）在厚壳贻贝幼虫附着变态中的调控作用,实验通过分析厚壳贻贝不同发育阶段幼虫转录组数据获得GABA受体相关蛋白基因（GABARAP）和GABA_B2受体基因(GABA_B2R),发现GABA_B2R在变态前期的眼点幼虫阶段相较于其他阶段幼体显著高表达。通过实时荧光定量PCR验证也得到相似的表达模式,显示GABA_B2R可能参与调控厚壳贻贝幼虫变态发育。药理学实验结果显示,10^-4 mol/L GABA对厚壳贻贝幼虫的变态具有诱导活性（27.2%±3.0%）。在拮抗剂实验中,10^-6～10^-4 mol/L荷包牡丹碱和CGP52432均显著抑制了厚壳贻贝幼虫变态,且抑制作用随浓度升高而增强。实验还发现GABA及其受体拮抗剂都抑制了厚壳贻贝幼虫的游泳行为。研究表明,GABA_A或GABA_...     

Effect of neuroactive compounds on larval metamorphosis of New Zealand geoduck (Panopea zelandica)

We present here the first laboratory study on the effects of pharmacologically active compounds on the larval metamorphosis of the New Zealand geoduck, Panopea zelandica (Quoy and Gaimard, 1835). Two batches of competent hatchery‐reared larvae were exposed to acetylcholine chloride, epinephrine hydrochloride and excess potassium ions in the form of KCl and K₂SO₄. None of the tested chemicals increased the proportion of metamorphosed geoducks, and in some cases, the chemical caused significant mortality, despite having been used extensively with other species, such as mussels and oysters. This might indicate that geoduck larval physiology and development differs from other bivalves. Geoducks may have evolved distinct chemoreceptor patterns that facilitate metamorphosis under environmentally favourable conditions for subtidal soft sediment habitats suitable for burrowing. Thus, further research is needed to identify alternative cues (e.g. conspecific adults, sediment characteristics and surface biofilm) and understand their role in settlement and metamorphosis. This information will aid the design of reseeding methods and contribute to the development of reliable hatchery production of geoduck spat.     

方格星虫胚胎与幼体发育的研究

为研究相同海域滩涂和池塘养殖方格星虫(Sipunculus nudus Linnaeus)营养组成的异同,比较了2种养殖方式下的方格星虫体壁脂肪酸、氨基酸、矿物元素和基本营养物质组成。结果显示,滩涂和池塘养殖方格星虫体壁的粗蛋白、粗脂肪、灰分、脂肪酸总量相近(P>0.05)。滩涂和池塘养殖星虫的C_22:0、C_{20:3 (n-3)}、C_16:1、C_{18:2 (n-6)}、C_23:0含量差异显著 (P<0.05),且作为硅藻脂肪酸特征的C_{16:1 (n-7)}/C_16:0比值和C_{20:5 (n-3)}也具有显著差异(P<0.05)。池塘养殖的方格星虫谷氨酸(Glu)、总氨基酸含量显著高于滩涂养殖(P<0.05),而必需氨基酸之间无显著差异(P>0.05)。池塘养殖方格星虫体壁和沉积物中的钾(K)、钠(Na)、镁(Mg)、钙(Ca)、硒(Se)含量均高于滩涂养殖方格星虫相应体壁和沉积物中的含量(P<0.05),而且2种养殖方式下的方格星虫体壁K、Se含量均显著高于相应沉积物中的含量(P<0.05)。综合分析表明,相同海域不同养殖方式并不会显著影响方格星虫的基本营养组成(粗蛋白、粗脂肪、灰分),但是对于Glu、总氨基酸以及C_22:0、C_{20:3 (n-3)}、C_16:1、C_{16:1 (n-7)}/C_16:0比值和C_{20:5 (n-3)}等具有影响。方格星虫对K、Na、Mg、Ca、Se具有一定程度的富集作用,而对于铁(Fe)、锌(Zn)、锰(Mn)、铜(Cu)、铅(Pb)、铬(Cr)、镉(Cd)、钴(Co)等元素无明显富集作用。     

日粮中鱼蛋白水解物对黄颡鱼生长、体成分和血清生理指标的影响

为了探讨鱼蛋白水解物对黄颡鱼生产性能的影响,以日本鳀粉为对照,以实用型黄颡鱼饲料配方模式为基础开展实验:1以30.5%鱼粉为对照(FM),在相同配方模式下,以6%鱼蛋白水解物(MPH6)替代20%的鱼粉;2以30.5%鱼粉为对照(FM),在无鱼粉日粮中分别添加3%(FPH3)、6%(FPH6)、12%(FPH12)鱼蛋白水解物;共设计5组等氮等能实验日粮,在池塘网箱中养殖黄颡鱼[初始体质量(30.08±0.35)g]60 d。结果显示:与FM相比,FPH12在SGR、FCR、PRR和FRR方面均无显著差异,而MPH6、FPH3、FPH6组SGR降低了15.45%~24.39%,FCR升高了32.14%~42.86%,MPH6、FPH6差异显著,在PRR和FRR方面,MPH6、FPH3、FPH6组PRR降低了21.11%~27.78%,MPH6组FRR降低了41.51%;全鱼水分、粗蛋白、粗脂肪和灰分各组间差异不显著,FPH3、FPH6、FPH12肌肉多种游离氨基酸水平显著高于FM,其中Thr、Val、His与其在日粮中的水平显著相关;FPH6组HSI显著低于FM,鱼蛋白水解物对CP、VSI、肠体比的影响不显著;血清AST、ALT、HDL、LDL、TP、CHOL、TG无显著差异,FPH3组ALB显著低于FM。研究表明:黄颡鱼日粮中,12%鱼蛋白水解物(干物质)与30.5%鱼粉在生长速度、饲料效率、血清生理指标等方面具有一定的等效性;过高的植物蛋白日粮影响了黄颡鱼的生产性能;饲喂鱼蛋白水解物日粮使黄颡鱼肌肉游离氨基酸的含量升高,特别是呈味氨基酸的含量增加。     

饥饿对草鱼血清游离氨基酸的影响

将池塘捕获的体重(1.70±0.80)kg的草鱼(Ctenopharyngodon idella)饲养在室内水族箱内,分别测定了空腹(禁食1 d,26样本)、饥饿15 d(15样本)、饥饿30 d(15样本)的草鱼血清游离氨基酸含量。结果显示:草鱼血清游离氨基酸总量基本恒定,空腹、饥饿15 d和饥饿30 d的氨基酸总量无显著差异;处于饥饿状态的草鱼血清游离必需氨基酸总量极显著地高于空腹状态,非必需氨基酸总量极显著地低于空腹状态;血清赖氨酸、缬氨酸、异亮氨酸、亮氨酸和胱氨酸含量因饥饿显著升高,而组氨酸、苯丙氨酸、天冬氨酸、丝氨酸、谷氨酸和酪氨酸因饥饿显著降低;饥饿15 d和饥饿30 d各氨基酸含量均未见差异。草鱼血清游离氨基酸含量在正常摄食情况下主要受饲料蛋白质影响,处于饥饿状态下主要来源于肌体蛋白质的分解,比较正常摄食后和饥饿状态下血清游离氨基酸的组成可评价饲料蛋白质的质量。     

Effects of dietary chlorogenic acid on growth,flesh quality and serum biochemical indices of grass carp (Ctenopharyngodon idella)

The study was to investigate effects of dietary chlorogenic acid (CGA) on growth performance, flesh quality and serum biochemical indices of grass carp (95.1 ± 0.3 g) (Ctenopharyngodon idella) fed seven different diets, including control diet, Eucommia ulmoides (EU)‐supplemented diet (20 g kg^–1) and CGA‐supplemented diets containing 100, 200, 400, 600 and 800 mg/kg CGA. Contents of collagen and alkaline‐insoluble collagen in muscle and skin were significantly increased by dietary CGA and EU (p < .05). Total essential amino acids (TEAA) and total amino acids (TAA) in muscle of grass carp fed EU diet or 400, 600 and 800 mg/kg CGA diet were significantly higher than those of fish fed control diet and 100 and 200 mg/kg CGA diet (p < .05). Fish fed 200–800 mg/kg CGA showed significantly lower muscle crude lipid content than EU, control and 100 mg/kg CGA groups (p < .05). Fish fed CGA‐supplemented diets (100–800 mg/kg) had significantly higher muscle fibre density and lower muscle fibre diameter than control group (p < .05). In conclusion, supplementation of CGA improved flesh quality of grass carp, and supplemental level of CGA for improving flesh quality and growth was estimated to be 400 mg/kg diet.     

饲料牛磺酸对尼罗罗非鱼生长、体成分及组织游离氨基酸含量的影响

本文探讨了饲料牛磺酸水平对尼罗罗非鱼幼鱼生长性能、体成分及游离氨基酸含量的影响。选用体重为5.89±0.03g的罗非鱼300尾,随机分为5个处理组,每个处理3个重复,每个重复20尾。在基础饲料中分别添加0、0.4%、0.8%、1.2%、1.6%的牛磺酸,配制成5种试验料,分别饲喂不同处理组的罗非鱼,饲养周期为56d。结果表明： 0.8%牛磺酸组罗非鱼增重率最高,且显著高于0%和1.6%组(P<0.05);饲料牛磺酸水平(0.4%-1.2%)显著提高了罗非鱼摄食率、肝脏指数和内脏指数,显著降低了饲料系数(P<0.05)。随着饲料牛磺酸水平的提高,鱼体粗蛋白质和粗脂肪含量随之升高,鱼体水分和粗灰分含量随之降低(P<0.05);以增重率为指标,通过二次曲线回归分析得出罗非鱼饲料牛磺酸最适需要量为0.75%。罗非鱼血清、肝脏、肌肉和全鱼中牛磺酸含量与饲料牛磺酸含量存在正相关关系,且牛磺酸添加组血清、肝脏、肌肉和全鱼牛磺酸含量显著高于对照组相(P<0.05)。罗非鱼肝脏和肌肉中游离氨基酸含量随饲料牛磺酸含量的增加均呈逐渐下降的趋势,且牛磺酸添加组肝脏和肌肉中游离氨基酸含量显著低于对照组(P<0.05)。     

The effects of methionine‐enriched Artemia nauplii on growth,amino acid profiles,absorption enzyme activity and antioxidant capability of common carp (Cyprinus carpio var. Jian) larvae

The effects of methionine‐enriched Artemia nauplii on growth, amino acid profiles and activity of absorption enzymes and antioxidant capability of common carp (Cyprinus carpio var. Jian) larvae were investigated in this study. The newly hatched Artemia nauplii enriched with methionine at four levels (0, 400, 800, 1,600 mg/L) for 16 hr was used as live food for common carp larvae for 21 days. The results demonstrated that the level of methionine in nauplii enriched with methionine increased significantly as the level of supplemental methionine rose (p < 0.05). The specific growth rate (SGR) and body length growth rate (BLGR) values in all experimental groups were significantly higher than those in the control group (p < 0.05) in the trial period. With the supplement of methionine, the amino acid profiles vary depending on the type of amino acid and/or the level of methionine applied. Further examination revealed that the activity of absorption enzymes in the 800 and 1,600 mg/L groups were all significantly higher compared to the other two groups (p < 0.05). Similar results on the antioxidant capability of fish larvae were also observed among the treatments. The changes in these physiological factors allowed for the control of the content of supplemental methionine in Artemia nauplii for larvae and potentially the ability to improve the growth performance of common carp larvae.     

Replacement of fish meal with wheat gluten in diets for Atlantic halibut (Hippoglossus hippoglossus): Effect on whole-body amino acid concentrations

The feasibility of replacing fish meal with wheat gluten (WG) in diets for Atlantic halibut (Hippoglossus hippoglossus) was studied. Four diets were produced containing 0, 10, 20 and 30% WG (60% crude protein and 27% lipid (dry matter (DM) basis)). The lysine concentration in these diets were 4.0, 3.6, 3.1 and 2.6% (dehydrated form), respectively. The diets were fed to triplicate groups of 60 g halibut in a 56-day comparative slaughter experiment. The data were analysed by ANOVA and regression. Fish growth (specific growth rate, overall mean 1.25 ± 0.03%/d) and feed efficiency (overall mean 1.63 ± 0.03 g gain/g DM intake) were good in this trial and were not influenced by dietary WG level. The whole-body protein concentration decreased significantly and the crude lipid concentration tended to increase with increasing dietary WG. These observations were taken as indications of problems with amino acid metabolism, and it was assumed that the diet containing 2.6% lysine was deficient in this amino acid. It was observed that the method of expression of the amino acid concentrations in the body was crucial for the detection of significant differences among treatments. Based on our results, we caution the use of crude protein as the denominator in the expression of amino acid concentrations. The finding in this dataset that dietary effects on the percentages of some amino acids in the fish are dependant on the use of hydrated or dehydrated amino acids encourages us to express the amino acids in the protein-bound (dehydrated) form, which also represents the form in which the overwhelming majority of amino acids are present in the body.The results from this trial indicate that WG is a suitable replacement protein source for fish meal, even at a high inclusion level of 20% of the diets. A further increase in the dietary WG level to 30% should be done with caution unless the diets are supplemented with lysine.     

Effects of short‐chain fructooligosaccharides on growth performance and hepatic intermediary metabolism in turbot (Scophthalmus maximus) reared at winter and summer temperatures

The effect of short‐chain fructooligosaccharides (scFOS) incorporation on growth, feed utilization, body composition, plasmatic metabolites and selected liver enzyme activities of turbot juveniles reared at winter (15 °C) and summer (20 °C) temperatures was studied. Four comparable diets were formulated to contain circa 50 : 50 fish meal and plant ingredients as protein sources. Experimental diets included increasing levels of scFOS (0, 5, 10 and 20 g kg^?1). Final weight was higher at 20 °C, but thermal growth unit, feed efficiency, nitrogen and energy retention were better at 15 °C. scFOS supplementation did not affect fish growth performance. Fish reared at 15 °C had higher liver glycogen, visceral and hepatosomatic indices. Liver lipids, plasma triglycerides, total lipids, cholesterol HDL and LDL were higher in turbot reared at 20 °C. Malic enzyme, fatty acid synthetase, alanine aminotransferase and glutamate dehydrogenase activities were higher in fish reared at 15 °C. Malic enzyme was lower in turbot fed with 20 g kg^?1 scFOS compared to control diet; however, fatty acid synthetase presented an increasing trend as dietary scFOS increased up to 10 g kg^?1. Glutamate dehydrogenase activity was higher in fish fed the control diet. Results seem to indicate no benefits of scFOS incorporation to diets on growth performance of turbot.     

光照强度对三疣梭子蟹呼吸代谢的影响

在实验室条件下,研究了光照强度(0,200,800,1 500,3 500 lx)对三疣梭子蟹耗氧率、排氨率、肌肉中乳酸含量、血淋巴能源物质及己糖激酶(HK)、丙酮酸激酶(PK)、琥珀酸脱氢酶(SDH)和乳酸脱氢酶(LDH)4种呼吸代谢酶活力的影响。结果发现,5种光照强度下,三疣梭子蟹的耗氧率和排氨率均有显著差异,200~1 500 lx下,蟹的耗氧率显著高于0和3 500 lx处理组(P0.05);1 500 lx下,蟹的排氨率显著低于其他处理组(P0.05);光照强度对三疣梭子蟹血淋巴中的总蛋白含量产生显著影响(P0.05),但对氧氮比和血淋巴中的其他能源物质未产生显著影响(P0.05);光照强度对三疣梭子蟹的肌肉乳酸含量产生显著影响(P0.05),1 500 lx下,蟹肌肉乳酸含量显著低于其他处理组(P0.05),说明该光照强度对蟹机体的胁迫小;1 500 lx光照下,蟹的HK和PK活力处在较高水平,表明机体糖酵解速率较高,产生更多的能量;SDH的活力处在较高水平,LDH处在较低水平,表明蟹的有氧代谢能力高,有利于蟹的持续运动。研究表明,1 500 lx光照下,三疣梭子蟹机体受到的胁迫小,整体代谢水平较高,是工厂化养殖较为理想的光照参数。     

日粮中添加鱼溶浆粉和鱼油对草鱼生长、肝脏脂肪含量和血清理化指标的影响

本实验探讨以猪肉粉为动物蛋白源的草鱼日粮中添加鱼溶浆粉和鱼油以补充鱼类所需的部分生长因子,对草鱼生长、肝脏脂肪含量和血清理化指标的影响,以期达到节约鱼粉的目的。在实用配方模式下,设计6种等氮等能饲料,分别是添加6%猪肉粉(6P)、3%猪肉粉+3%鱼溶浆粉(3P3SW)、6%鱼溶浆粉(6SW)、3%猪肉粉+3%鱼溶浆粉+2%鱼油(3P3SW2O)、6%鱼溶浆粉+2%鱼油(6SW2O)和6%鱼粉(6F,对照)。在池塘网箱中饲喂(80.0±2.0)g的草鱼72 d。结果表明,6P和6F在SGR、FCR、PRR、ERR和HSI方面均无显著差异(P>0.05)。添加鱼溶浆粉后,3P3SW、6SW与6F相比,SGR提高了9.1%～9.6%,FCR下降了8.5%～11.2%,差异显著(P<0.05),但3P3SW和6SW无显著差异(P>0.05),同时,在PRR、FRR和ERR方面,3P3SW、6SW均有一定程度提高。添加鱼油后,3P3SW2O、6SW2O和3P3SW、6SW比,SGR分别下降了9.7%、15.4%,FCR分别上升了6.9%、31.1%,除3P3SW2O和3P3SW的FCR之外,其余差异显著(P<0.05);在PRR和ERR方面,3P3SW2O、6SW2O均有一定程度下降;同时,3P3SW2O、6SW2O的FRR和肝脏粗脂肪含量都出现不同程度增高,HSI增大,血清TBA、CHOL、HDL和LDL与肝脏粗脂肪呈现出相同趋势,且上述指标均是6SW2O组最高,与其余各组均存在显著差异(P<0.05)。此外,在对饲料中游离氨基酸和生物胺与FCR和SGR的相关性分析中,发现游离Lys、Tau和Put与FCR和SGR的Pearsion相关系数都大于0.8,且符合二次函数关系。因此,鱼溶浆粉对草鱼的促生长作用优于鱼粉,在无鱼粉日粮中添加少量的鱼溶浆粉能满足草鱼需求,节约鱼粉用量,这种促生长作用与饲料中游离Lys、Tau和Put的关系密切;由于鱼油促使脂肪在体内和肝脏沉积,加重肝脏脂质代谢负担,加上其易氧化变质特性,限制了它在水产饲料中的使用。     

Effects of dietary amino acid profile on growth performance, key metabolic enzymes and somatotropic axis responsiveness of gilthead sea bream (Sparus aurata)

Juvenile gilthead sea bream were fed to visual satiety with isonitrogenous diets based on fish meal and different plant ingredients (33–35% replacement) supplemented with free amino acids to meet the desired indispensable amino acid (IAA) profile and dispensable amino acid (DAA) content. In diets M and WB, IAA profile and DAA content resemble that of the muscle or whole body, respectively. In diets MGlu and WBGlu, DAA content was increased by adding -glutamic acid (Glu) and thus the IAA/DAA ratio varied from 1.13 (diet M) to 0.80 (diet WBGlu). Growth rates were not significantly different among experimental groups, but feed conversion ratio and nitrogen retention were impaired by the decrease of dietary IAA/DAA ratio. Postprandial ammonia excretion increased with the increase of dietary DAA content irrespective of IAA profile. Conversely, hepatic activity of glutamate dehydrogenase (GDH) was lower in fish fed diet WBGlu than in fish fed diet M. Hepatic growth hormone (GH) binding was not significantly affected by the dietary treatment, but circulating levels of insulin-like growth factor-I (IGF-I) and GH were, respectively, down- and up-regulated in fish fed diet WBGlu, which suggests some defect in the transmission of GH receptor signal. Fat retention and hepatic activities of lipogenic enzymes (glucose-6-phosphate dehydrogenase, G6PD; malic enzyme, ME) were decreased in fish fed diet MGlu. Key metabolic enzymes of hepatic glycolysis (glucokinase, GK) and gluconeogenesis (phosphoenolpyruvate carboxykinase, PEPCK) were also altered in this group of fish. Since soybean meal concentration was highest in diet MGlu, results on lipid and carbohydrate metabolism can be primarily attributed to this component of the diet. In contrast, data on growth performance, ammonia excretion and GH axis mainly reflect changes in the dietary amino acid profile, which reveals that a muscle IAA profile and a high IAA/DAA ratio are important in feeds for gilthead sea bream.     

饲料磷水平对吉富罗非鱼肠道磷和脂肪酸转运及甘油三酯沉积的影响

摘要:为了探究饲料中不同磷水平对罗非鱼肠道磷和脂肪酸转运及甘油三脂沉积的影响,我们配制了3组不同磷水平的饲料,饲料中磷含量分别为1.21 %（LPD）、1.75 %（MPD）和2.66 %（HPD））,用配制的饲料投喂罗非鱼10周。结果显示：与LPD组相比,HPD组显著增加罗非鱼肠道钠磷协同转运体SLC34A2基因（95.7%）和蛋白（200.1%）的表达,增加肠道组织总磷含量（79.2%）;HPD组上调脂肪酸吸收基因cd36、fabp1、fabp2和fatp1及甘油三酯合成基因dgat1的表达（11.2%~54.0%）,下调脂肪酸转运基因apob-100的表达（37.7%）,增加游离脂肪酸（NEFA）的含量（241.1%）。与LPD组相比,HPD组显著增加罗非鱼肠道组织甘油三酯（TG）的含量（42.9%）。 综上,我们的研究表明,饲料中高磷水平增加肠道组织TG的含量,上调脂肪酸吸收途径和抑制脂肪酸排出途径。我们的研究为深入揭示磷影响鱼类磷代谢及脂类代谢的机理奠定基础。     

越冬期间投喂不同饵料对中华绒螯蟹扣蟹存活、营养组成、消化及免疫力的影响

为研究越冬期间投喂不同饵料对中华绒螯蟹扣蟹存活、营养组成、消化及免疫力的影响,本实验比较了越冬期间不投喂(NF组)、投喂配合饲料(CF组)以及投喂冰鲜鱼(CTF组)对扣蟹存活率、营养组成、消化酶、抗氧化酶和免疫酶活性的影响。每个处理3个重复,实验周期为70d。结果表明：（1）越冬过后,CF组和CTF组扣蟹的增重率和肝胰腺指数显著高于NF组(P＜0.05),而三组间存活率无显著差异(P＞0.05);（2）越冬过后,CF组和CTF组扣蟹躯体和肝胰腺中脂肪和碳水化合物含量显著高于NF组(P＜0.05),CF组扣蟹躯体和肝胰腺碳水化合含量显著高于CTF组(P＜0.05 ),而NF组扣蟹肝胰腺水分显著高于CF组和CTF组(P＜0.05)。无论投喂与否,越冬过后躯体蛋白质含量显著下降,而肝胰腺中蛋白质显著增加(P＜0.05);（3）脂肪酸组成,CF组扣蟹躯体和肝胰腺中C18:2n6(LA)含量显著高于NF组和CTF组,而CTF组C20:5n3(EPA)和C22:6n3(DHA)含量显著高于NF组和CF组(P＜0.05);（4）越冬过后,扣蟹肝胰腺消化酶CF组胃蛋白酶(pepsin)和α-淀粉酶(α-AMS)活性显著高于NF组和CTF组(P＜0.05);（5）扣蟹抗氧化能力,肝胰腺和血淋巴中NF组超氧化物歧化酶(SOD)活性显著高于CF组和CTF组(P＜0.05),CF组总抗氧化能力(T-AOC)活性显著高于NF组和CTF组(P＜0.05),CTF组扣蟹血淋巴和雌性扣蟹肝胰腺丙二醛(MDA)含量显著高于NF组和CF组(P＜0.05);（6）扣蟹免疫能力,CF组酸性磷酸酶(ACP)和碱性磷酸酶(AKP)活性显著高于NF组(P＜0.05)。综上所述,中华绒螯蟹扣蟹越冬期间应该适量投喂饵料,投喂配合饲料组扣蟹的存活率、肝胰腺指数、增重率以及营养物质积累优于投喂冰鲜鱼组,而且投喂配合饲料有利于扣蟹消化,增强扣蟹抗氧化和免疫能力。本研究为中华绒螯蟹扣蟹越冬饵料的合理投喂提供科学参考和理论基础。