Annual variations of the plasmatic levels of glucose and amino acid and daily changes under different natural conditions of temperature and photoperiod in Gilthead Sea bream (Sparus aurata, L.)

Daily and annual changes in the plasmatic glucose and amino acid concentration have been determined in Sparus aurata L. Fish (average weight 330 g) were kept in cages under natural conditions of temperature and photoperiod and fed with a commercial diet. The months studied were chosen to establish whether there is any influence on the plasmatic glucose and amino acid concentration due to the change in temperature and photoperiod (equal photoperiod and different temperature, March and October; different photoperiod and equal temperature, May and November; and different photoperiod and temperature, June and January). To study the daily profile of glucose and amino acids concentrations, blood was extracted from six fish every 3 h during 24 h. Annual changes were determined as the average of the samples obtained during 1 day. Results show an annual rhythm with acrophase in June with a positive correlation with photoperiod for glucose and amino acids and with temperature only for amino acids. Daily profiles are rhythmical with a period of 24 h except in November with a period of 8 h for amino acids.     

Phytic Acid‐Induced Inhibition of Digestive Protease and α‐Amylase in Three Indian Major Carps: An in vitro Study

Antinutritional effects of phytic acid (myoinositol hexaphosphate, IP6) on growth and digestibility in fish have been reported. However, specific effect of IP6 on the digestive enzymes in fish has not been addressed. In this study, inhibitory effect of synthetic IP6 (Phytic acid sodium salt, 90% purity) on the activity of the digestive protease and α‐amylase in rohu, Labeo rohita; catla, Catla catla; and mrigal, Cirrhinus mrigala has been investigated in vitro. Graded levels (12.5, 25, 50, 100, 150, and 200 µg/mL) of IP6 were added to the reaction mixtures containing enzyme extracts and substrate solution in triplicate to detect any change in enzyme activity. Results of the experiment revealed that IP6 significantly inhibit/lower activities of the digestive enzymes in a dose‐dependent manner, as evident from the regression equations (F values significant at P < 0.001 level). Apparently, irrespective of the fish species studied IP6‐induced inhibition of α‐amylase activity was greater than protease activity. Among the three fish species studied, C. mrigala appeared to be more sensitive to IP6 for both α‐amylase and protease activity. Enzyme activity was least affected in C. catla. Results of the study might raise concern while incorporating IP6 rich plant‐derived feed ingredients in aqua feed preparation.     

The effects of dietary inulin on growth performances,survival and digestive enzyme activities of common carp (Cyprinus carpio) fry

This study was conducted to investigate the effects of dietary inulin on growth performance, diet utilization, survival rate, carcass composition and digestive enzymes activities (amylase, lipase and protease) of carp (Cyprinus carpio) fry (0.55 ± 0.02 g). After acclimation, fish were allocated into 9 tanks (40 fish per tank) and triplicate fish groups were fed, control diet (0 g) or diets containing 5 g and 10 g inulin kg^?1 for 7 weeks. No significant effect on growth performance and diet utilization of fish fed inulin compared with the control group was observed. However, supplementation of inulin significantly increased survival rate and carcass lipid content, while carcass protein content significantly decreased. Dietary inulin had no significant effects on digestive lipase, protease and amylase activities.     

Ontogeny of protease, amylase and lipase in the alimentary tract of hybrid Juvenile tilapia (Oreochromis niloticus × Oreochromis aureus)

Juvenile tilapias (Oreochromis niloticus × O. aureus), with average body weights of groups I, II and III of 55.14, 122.82, and 225.68 g respectively were used to study changes in the activity of protease, amylase, and lipase in different organs and sections of the alimentary tract. Additionally, tract containing digesta, which is closer to physiological conditions, may help reveal the mechanisms of whole chemical digestion process. Another group of tilapias (mean body weight of 111.81 ± 0.14 g) was used to analyze changes in activity of protease, lipase, and amylase in response to varying pH and temperatures. The activity of enzymes in all digestive organs increased when body weight increased from 55 to 122 g, and the activity further increased when the weights increased from 122 to 225 g. The rates of increase in digestive enzyme activity were significantly greater than the rates of growth of the fish. When the activity was compared in different sections of the tract, a similar regularity was found for the three enzymes in all fish. The highest amounts of activity were seen in the foregut and the lowest in the rectum, with the middle amount of activity in the hindgut. The pH ranges for the maximum activity of tilapia protease in the stomach and intestine were 1.6–3.3 and 9.5–10.5 respectively and the optimal temperature in these organs was 55°C. The pH ranges for the maximum amylase activity in the intestine and hepatopancreas were 6–7 and 7.5 respectively, and high amylase activity in these organs was found at 25–35°C. The activity of lipase in the intestine remained unchanged at pH 6.0–9.0 and with temperatures between 25 and 35°C. These results suggest that the ability of tilapia to utilize feed varies at different growth stages and remains relatively stable with changes in environmental pH and temperature, which should be taken into account when designing feed formulas for tilapia.     

Influence of 5′‐inosine monophosphate and 5′‐guanosine monophosphate on growth,feed digestibility and activity of digestive enzymes in turbot Scophthalmus maximus

We evaluated the influence of different proportions of 5′‐inosine monophosphate (IMP) and 5′‐guanosine monophosphate (GMP) on growth, feed digestibility and activity of digestive enzymes of turbot Scophthalmus maximus. Weight gain and daily feed intake were significantly higher in S. maximus fed with IMP or GMP, in comparison with fish fed with neither IMP nor GMP. The growth of 0.05% IMP + 0.05% GMP group was the best, and the intestinal digestive function was improved. The addition of IMP and GMP to fish diets significantly increased the apparent feed digestibility coefficient of dry matter and protein, as well as intestinal protease activity. The highest intestinal protease activity was observed in fish fed with 1 g/kg IMP. However, the lipase activity in hepatopancreas decreased significantly after addition of nucleic acid. According to our results, the optimal level of dietary IMP is 1 g/kg, which is in line with most of the growth performance and feed digestibility.     

Timing and duration of constant light affects rainbow trout (Oncorhynchus mykiss) growth during autumn–spring grow-out in freshwater

Photoperiod enhancement of growth is becoming an area of increasing interest as a means of enhancing rainbow trout production efficiency in commercial practice. This paper examines the possible implications of shortening periods of constant light (LL) exposure on rainbow trout growth during autumn–spring grow-out under ambient water temperatures in freshwater to portion size. Triplicate groups of juvenile all-female rainbow trout were permanently exposed to LL in October, November, December or January. Growth was monitored and compared with those maintained under a simulated natural photoperiod (SNP) until the following May. Permanent exposure to LL (all treatments) resulted in significantly greater weight gain of rainbow trout than those under SNP. Furthermore, greatest growth was achieved when fish were left permanently exposed to LL from October. These findings suggest there may be implications for fish farmers if the period of photoperiod exposure is reduced, or timing of application is not considered with regards to ambient water temperatures.     

菊黄东方鲀当年鱼种养殖阶段消化酶活性研究

为了研究池塘养殖菊黄东方鲀（Takifugu flavidus）鱼种生长及肠组织中消化酶活性随生长的变化,2012年5－11月进行室外养殖试验,池塘面积0.2 hm2,水深1.5～2.0 m,鱼苗体长1.2~1.5 cm,放养密度为22.5 万尾/hm2,试验用海水盐度5~15,水温为15~35℃,pH 8~9;测定当年鱼种不同生长阶段的体长、体质量、肝重、肠长等生长指标,通过生物化学方法测定了其肠组织主要消化酶活性。结果表明,菊黄东方鲀幼鱼体长、体质量与养殖天数均呈指数相关（L=27.07e0.0088t, W=1.0982e0.0262t）;体长与体质量呈幂函数增长相关（W=3×10-5L3.1070）,且为异速生长。不同生长阶段菊黄东方鲀肝体比、比肠长、肥满度的变化显著（P<0.05）;肝体比随生长呈显著上升趋势（P<0.05）,变化范围为4.15%~20.23%;比肠长则呈显著下降趋势（P<0.05）,变化范围为0.97%～2.33%,不同生长阶段肥满度变化为3.99%～5.11%。菊黄东方鲀肠组织碱性蛋白酶和淀粉酶活性均随生长呈显著降低趋势（P<0.05）,最大值均出现在养殖40 d（83.11 U/mg与3.13 U/mg）;酸性蛋白酶活性呈先下降、后上升趋势（P<0.05）,最小值（0.34 U/mg）与最大值（0.86 U/mg）分别出现在113 d和166 d;脂肪酶活性随生长变化不显著（P>0.05）。研究表明,菊黄东方鲀鱼种的生长与养殖条件的改变存在密切关系;肝体比、比肠长等与鱼的发育及营养摄入存在一定关系;肠组织不是生成蛋白酶和淀粉酶的主要器官。     

长薄鳅幼鱼消化道指数和消化酶活性研究

测定了长薄鳅(Leptobotia elongate Bleeker)幼鱼(8.0～110.1 g)的消化道指数和不同体重组(10 g、30 g、50 g)幼鱼的胃、肝胰脏、前肠、中肠、后肠的淀粉酶、胃蛋白酶、胰蛋白酶及脂肪酶活性。结果:(1)长薄鳅幼鱼肝指数平均为(1.400±0.004)%,比肠长平均为(0.418±0.080),体重与体长呈幂函数相关,相关式为:W=0.019L2.818 1(R2=0.948,P<0.01,n=43);鱼体肥满度在30 g组中最高。(2)各部位消化酶活性均以蛋白酶>脂肪酶>淀粉酶;各体重组淀粉酶活性在肝胰脏中最高(P<0.05);蛋白酶活性在胃和中肠中较高;脂肪酶活性沿消化道从前至后升高;(3)各部位淀粉酶活性在各体重组间变化不大,胃蛋白酶、肠段胰蛋白酶和脂肪酶活性随体重增加而下降。本研究认为长薄鳅幼鱼为杂食、偏肉食性,其消化酶活性存在组织特异性,体重30 g左右是其营养需求转变或者生长发育的重要时期。     

Effects of rearing temperature and dietary short‐chain fructooligosaccharides supplementation on allochthonous gut microbiota,digestive enzymes activities and intestine health of turbot (Scophthalmus maximus L.) juveniles

The gut microbiomes of fish play important roles in host development, digestion and health. Evidence suggests that abiotic factors, such as diet and rearing temperature, could affect fish gut microbiota. In this study, the effect of dietary short‐chain fructooligosaccharides (scFOS) on turbot intestinal health, microbiota and digestive enzymes was investigated at two rearing temperatures: 15 and 20 °C. Four practical diets were supplemented with scFOS at 0, 5, 10 and 20 g kg^?1. scFOS did not affect fish performance. PCR‐DGGE did not show differences in bacterial profiles between dietary treatments; however, the number of operational taxonomic units, richness and diversity were higher at 20 °C. Enzyme activities in the foregut were not affected by rearing temperature, while in the hindgut, enzyme activities were higher at 15 °C. Total alkaline protease, α‐amylase and lipase activities in the foregut were higher in fish fed 20 g kg^?1 scFOS. Prebiotic supplementation had no effect on hindgut α‐amylase activity, while lipase activity of fish reared at 20 °C was higher in fish fed diet with 5 g kg^?1 scFOS. No differences were observed in intestinal morphology. This was the first study to simultaneously evaluate the effect of dietary prebiotic level and rearing temperature on fish intestinal microbiota and health.     

Effect of temperature and photoperiod on the reproductive condition and performance of a tropical damselfish <Emphasis Type="Italic">Chrysiptera cyanea</Emphasis> during different phases of the reproductive season

Effects of temperature and photoperiod on the reproductive activity of a reef associated tropical damselfish Chrysiptera cyanea were evaluated under three phases with different environmental patterns, phase I (April–May; increasing water temperature and photoperiod), phase II (June–July; increasing water temperature and peak/decreasing photoperiod), and phase III (August–September; peak/decreasing water temperature and decreasing photoperiod). When the fish were reared at 20, 25, or 30°C under natural photoperiod, the reproductive conditions differed within and among the phases depending on experimental temperature and environmental patterns. From phases I through III, ovaries with vitellogenic oocytes were notable only at 25°C, whereas regressing and immature oocytes were noticed at 20 and 30°C. The fish underwent active spawning at 25°C, whereas no or few spawnings were observed at other temperatures. In phase III, there was a resultant prevention of decrease in the gonadosomatic index and disappearance of vitellogenic oocytes in the ovaries of fish under a long photoperiod (LD14:10) compared to those under a short photoperiod (LD10:14). These results indicate that a long photoperiod with a suitable range of water temperature is a principal determinant in continuity of reproductive activity and performance, and that a high temperature has a negative impact on their ovarian development.     

Effects of non-starch polysaccharides enzyme, phytase and citric acid on activities of endogenous digestive enzymes of tilapia (Oreochromis niloticus × Oreochromis aureus)

Non-starch polysaccharides (NSPs) enzyme, phytase and citric acid have been shown to increase digestibility in pigs, poultry and some fish. To examine their roles in digestion in tilapia ( Oreochromis niloticus  ×  Oreochromis aureus ), the present study was designed to evaluate their effects on activities of a number of endogenous digestive enzymes in tilapia. Neither NSPs enzyme (1 g kg⁻¹) nor phytase (1 g kg⁻¹) affected the activities of protease in digestive organs. In contrast, NSPs enzyme increased the activities of amylase in the hepatopancreas and intestine by 11.4% and 49.5%, respectively, while phytase (1 g kg⁻¹) increased the activities of amylase in the hepatopancreas and intestine by 14.0% and 24.1%, respectively. Citric acid (10 g kg⁻¹) increased the activities of protease in stomach by 29.6%, but reduced the activities of protease in the intestine by 35.1%. Citric acid increased the activities of amylase in the hepatopancreas and intestine by 30.7% and 29.4%. Lipase activities were not affected by NSPs enzyme, phytase or citric acid. Above results suggest that NSPs enzyme, phytase and citric acid primarily influence the activities of amylase in digestive tract of tilapia.     

Inhibitory effect of <Emphasis Type="Italic">Pistia</Emphasis> tannin on digestive enzymes of Indian major carps: an in vitro study

Aquatic weeds are one of the major unconventional feed ingredients tested for aquafeed formulation. Tannin content in the water lettuce, Pistia, has been quantified (26.67 mg g⁻¹; dry weight) and graded levels of which (12.5–200 μg) have been incorporated in the reaction mixtures to evaluate any change in the in vitro activity of the principal digestive enzymes from the three Indian major carps (IMC), namely rohu (Labeo rohita), catla (Catla catla) and mrigala (Cirrhinus mrigala). Result of the experiment revealed that the Pistia tannin (PT) significantly inhibit/lower the activities of the digestive enzymes from three IMCs in a dose-dependant manner, even at very low concentration. Significant variation in the reduction of the enzyme activities was noticed between the three fish species, as well as between the three enzymes studied. Among the three species studied, digestive enzymes from L. rohita were found to be the most sensitive to the PT, whereas enzymes from C. catla were found to be comparatively least affected. On the other hand, protease and lipase activities were comparatively more affected than the amylase activity. The results of the study suggest that more stress should be given on the elimination of tannin while incorporating feed ingredients of plant origin in fish diets.     

卵形鲳鲶消化酶活性的研究I．成鱼和幼鱼消化酶活性在不同消化器官中的分布及其比较

比较研究了卯形鲳够（Trachinotus ovatus）成鱼和幼鱼阶段消化酶（蛋白酶、淀粉酶、脂肪酶）在不同消化器官中的活性。结果表明：1）成鱼蛋白酶在不同消化器官中的活性大小依次为胃〉前肠〉中肠〉幽门盲囊〉后肠〉肝;淀粉酶活性为前肠〉后肠〉幽门盲囊〉中肠〉肝〉胃;脂肪酶活性为前肠〉中肠〉后肠〉幽门盲囊〉肝〉胃。2）幼鱼蛋白酶在不同消化器官中的活性大小依次为胃〉肠〉幽门盲囊〉肝;淀粉酶活性为肠〉幽门盲囊〉肝〉胃;脂肪酶活性为肠〉幽门盲囊〉肝〉胃。3）成鱼不同消化器官中蛋白酶和淀粉酶的活性均小于幼鱼,成鱼胃和幽门盲囊的淀粉酶活性与幼鱼的差异显著;幼鱼胃脂肪酶活性大于成鱼,但其他器官的活性均小于成鱼。卵形鲳鳕幼鱼不同消化器官中的3种消化酶活性大小顺序与成鱼基本相似。     

Differences in the digestive biochemistry between the intertidal clam, Ruditapes decussatus, and the subtidal clam, Venerupis pullastra

The present study was aimed to evaluate differences in physicochemical characteristics (pH and temperature optima) of the main digestive enzymes (amylase, cellulase, laminarinase, and protease) in two commercially important bivalves, the intertidal clam, Ruditapes decussatus, and the subtidal clam, Venerupis pullastra, as well to assess individual variability of such activities. The assays were performed on extracts obtained from the digestive glands and crystalline styles of individuals collected in the wild and laboratory-conditioned during 1 week. In both species, maximum activity for amylase and cellulase was measured at pH 6 and that of laminarinase at pH 5.5, while pH profiles of protease activity showed important differences between them. Temperature profiles also showed interspecific variations, mainly in laminarinase. Carbohydrase activities were comparatively much higher in R. decussatus and proteolytic activities in V. pullastra. The observed differences both in physicochemical characteristics and relative importance of digestive enzymes are discussed in relation to the amount and type of food available in their respective habitats.     

Temperature and dietary starch level affected protein but not starch digestibility in gilthead sea bream juveniles

A study was carried out with gilthead sea bream juveniles to assess the effect of water temperature (18 and 25°C) and dietary pregelatinized starch level (10, 20 and 30%) on digestibility of protein and starch and on the activity of proteolytic and amylolytic enzymes. ADC of pregelatinized starch was very high (>99%) irrespectively of dietary inclusion level, and it was not affected by water temperature. ADC of protein was also high (>90%) but improved at the higher water temperature. Dietary starch interacted with protein digestibility, which decreased as dietary starch level increased. Temperature affected both acid and basic protease activities, with acid protease activity being higher at 25°C and basic protease activity being higher at 18°C. However, total proteolytic activity and amylase activities were not affected by water temperature. Dietary carbohydrate exerted no effect on proteolytic or amylolitic activities. It is concluded that gilthead sea bream juveniles digest pregelatinized starch very efficiently irrespective of water temperature, due to adjustments of amylase activity to cope with temperature differences. Pregelatinized starch interacts negatively with protein digestibility, with the ADC of protein decreasing as dietary starch levels increase.     

温度和pH对马氏珠母贝肝胰脏消化酶活力的影响

2006年4月,从湛江市流沙港马氏珠母贝养殖群体中挑选黄壳色个体为亲本.繁殖黄壳色选系F1.2007年10月,在黄壳色选系F1随机取样,分析了温度和pH对马氏珠母贝肝胰脏消化酶活力的影响.试验结果表明,温度为15～50℃时,淀粉酶和纤维素酶的最适温度分别为25,40℃;温度为15～75℃时,蛋白酶的最适温度为55℃.不...     

温度对沙塘鳢消化酶活力的影响

通过改变反应温度分析了一定pH值下沙塘鳢(Odontobutis obscura)三种主要消化酶活性的变化。结果表明:pH6.0时,沙塘鳢肝胰脏、胃、肠道淀粉酶的最适温度分别为25℃、35℃、25～30℃;肝胰脏和肠道pH7.5时,胃pH2.0时,蛋白酶的最适温度分别为40℃、35℃、35℃;pH7.5时,肝胰脏、胃、肠道脂肪酶的最适温度分别为30℃,40℃,25℃。淀粉酶和脂肪酶活性分布是肝胰脏最高,胃次之,肠道最低;蛋白酶活性分布是胃最高,肝胰脏和肠道稍低。     

Ontogeny of the digestive tract of thick lipped grey mullet (Chelon labrosus) larvae reared in “mesocosms”

This work describes the ontogeny of the digestive tract in thick lipped grey mullet (Chelon labrosus) larvae reared until day 36 post-hatching with the semi-extensive technology in mesocosms. Diet was constituted by live preys, rotifers, Artemia and wild zooplankton, then compound diet was added from day 20 (p. h.). Linear growth, weight growth and digestive enzymes specific activities were studied during larval ontogeny. Pancreatic enzymes (trypsin and amylase) and intestinal enzymes (leucine-alanine peptidase “Leu-ala”, aminopeptidase N “AN” and alkaline phosphatase “AP”) were assayed in larvae sampled throughout the rearing trial to evaluate gastrointestinal maturation along the development.The trypsin specific activities were very high during the first two weeks and then declined as observed in marine fish species. A following increase in trypsin specific activity from day 20 was attributed notably to ingestion of particle compound diet. In contrast to the pattern generally described in fish larvae, amylase specific activity showed a continuous increase. This could be attributed to the fact that C. labrosus is an omnivorous species and suggests that the fish might be able to use efficiently diets containing higher levels of starch or other carbohydrates since the end of larval development.Relative expression of intestinal brush border membrane enzymes (AP and AN) and cytosolic enzyme (Leu-ala), showed an abrupt increase of both AP/leu-ala and AN/leu-ala ratios at day 8 (p. h.), indicating that maturation of intestinal tract in C. labrosus larvae is particularly precocious. It is assumed that larvae of C. labrosus might support early co-feeding and weaning strategies, which could reasonably be initiated since mouth opening.     

澳洲宝石鱼营养成分和消化酶活性的研究

采用多重比较法分析澳洲宝石鱼肝胰脏、肠道、胃组织的淀粉酶、蛋白酶和脂肪酶活性以及肌肉的营养成份。结果表明,宝石鱼肌肉中蛋白质含量为17.87%,脂肪含量为8.05%,糖类含量为3.21%,灰分含量为2.83%,水分含量为70.29%。说明宝石鱼是营养价值较高的鱼种。三种消化酶活力分布不同,淀粉酶、蛋白酶比活力大小均为:肠道>胃>肝胰脏,且三者间均存在极显著差异(P<0.01),而胃蛋白酶活力(pH3.0)最高;脂肪酶比活力在胃、肠道不存在显著性差异,但极明显高于肝胰脏(P<0.01)。三种消化酶在同一消化器官内的活性,肝胰脏、肠道和胃均表现为蛋白酶>淀粉酶>脂肪酶,A/P比值均小于1。表明澳洲宝石鱼为肉食性或偏肉食性鱼类。     

Enzymes from the gut bacteria of Atlantic cod,Gadus morhua and their influence on intestinal enzyme activity

Gut‐associated bacteria of fish are known to produce enzymes which aid in digestion. The presence and activities of these bacteria in cold‐water fishes like Atlantic cod are less known. Therefore, we have characterized the activities of extracellular enzymes of GP21 (Pseudomonas sp.) and GP12 (Psychrobacter sp.), two bacteria isolated from the gastrointestinal tract of Atlantic cod. Additionally, we examined if these bacteria when delivered through feeds could influence the activity of selected intestinal enzymes. GP21 was able to produce amylase, chitinase, cellulase and protease, whereas GP12 could produce only chitinase and protease. These enzymes were produced extracellularly and they were found to be catalytically active at acidic conditions (pH 2–5) and at temperatures ranging from 15 to 30 °C. Orally delivered bacteria could possibly influence the activity of intestinal enzymes after 40 days, rather than after 20 days of feeding. Thus GP21 and GP12, the potential probiotic organisms, could support digestion in Atlantic cod.