Apparent digestibility coefficients of animal and plant feed ingredients for juvenile Pseudobagrus ussuriensis

A study was conducted to determine apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipid, gross energy, phosphorus and amino acids (AAs) from Peruvian fish meal (PFM), native fish meal (NFM), meat bone meal (MBM), dried daphnia meal (DDM), soybean meal (SBM), full‐fat soybean (FSBM), cottonseed meals (CSM), rapeseed meal (RSM) and corn gluten meal (CGM) for Pseudobagrus ussuriensis (7.8 ± 0.06 g). Test diets were formulated to contain a 70:30 mixture of reference diet to test ingredient with chromic oxide (5 g kg^–1) serving as the inert marker. ADCs of DM ranged from 49.94% (CGM) to 87.11% (PFM), the highest ADCs of DM were observed in PFM and the lowest was found in CGM. ADCs of CP in the test ingredients ranged from 74.92% (CGM) to 93.41% (SBM). ADCs of crude lipid ranged from 51.80% (CGM) to 94.07% (PFM) for fish. ADCs of energy ranged from 56.42% (CGM) to 90.09% (PFM). ADCs of phosphorus ranged from 21.81% (CSM) to 65.70% (PFM). AA availability for the test ingredients followed a similar pattern to ADCs of CP, in which values for PFM, NFM and MBM were generally higher (p < .05) than those of other protein ingredients. Among all plant meals, the AA availability values in SBM were higher (p < .05) than those in CGM, CSM and RSM. The availability of most AAs in CGM was the lowest (p < .05) among all tested ingredients. In conclusion, PFM and NFM are good sources of available protein and AAs. When fishmeal supply is limited, MBM and DDM are substitutes for fishmeal reduction in P. ussuriensis diets; at the same time, SBM and FSBM are also very acceptable protein feedstuffs. However, CSM, RSM and CGM could not be used at high levels in P. ussuriensis diets because of their inferior digestibilities.     

乌龟肌肉营养价值的评定

分析结果表明,乌龟的水分、总糖、灰分含量分别为80 24%,0 66%和0 95%。乌龟肌肉的蛋白质含量达16 64%,必需氨基酸和鲜味氨基酸分别占氨基酸总量的49 16%和43 39%,氨基酸组成中以Glu含量最为丰富,Ie是第一限制性氨基酸,氨基酸分为82 63;乌龟肌肉脂肪含量为1 51%,脂肪酸组成以C18∶1为主,达39.32%,其次为C16∶0及C22∶6,不饱和脂肪酸占脂肪酸总量的76 83%。     

Intra- and interspecific phenotypic characteristics of fish-pathogenic Edwardsiella ictaluri and E. tarda

Intra‐ and interspecific characteristics of fish‐pathogenic Edwardsiella ictaluri, and E. tarda were determined by numerical analysis of gel electrophoresed protein profiles, fatty acid methyl esters (FAMEs) and immunoblotting. The 18 E. ictaluri isolates revealed a high degree of homogeneity (70% similarity or higher) in their protein profiles and 95% similarity in their FAME, while the nine E. tarda isolates revealed 30% similarity in their protein profiles and 95% similarity in their FAME. Immunoblots probed for antigenic epitopes with goat antiserum produced against E. ictaluri and E. tarda, respectively, revealed that E. ictaluri were more homogeneous compared with the E. tarda isolates. Overall, there was a considerable degree of relatedness between the two species. Our findings suggest that phenotypically E. ictaluri represents a clonal bacterial population structure compared with the less monomorphic E. tarda.     

The influence of dietary fatty acid and fasting on the hepatic lipid metabolism of barramundi (Lates calcarifer)

For many fish species, dietary fish oil (FO) has been substituted with other oils such as poultry oil (PO) without affecting growth performance. However, in barramundi, the mechanisms by which fatty acid metabolism is regulated are poorly understood, and the effects of FO substitution are unknown. This study defined changes in the expression of genes controlling the metabolism of fatty acids in barramundi over a 24‐h time period after a single meal. From one to 12 h after a single feeding event, the expression of fatty acid synthesis genes in the liver was upregulated, while genes involved in the β‐oxidation showed minimal alteration. However, the expression of β‐oxidation genes was significantly correlated with the expression of genes regulating fatty acid synthesis. In a second experiment, the changes in liver fatty acid composition and gene expression were defined after FO was substituted with PO. Liver fatty acid profile reflected the diet composition, with some subtle exceptions supporting the enrichment of certain long‐chain polyunsaturated fatty acids in the liver. The fish from all experimental groups preferentially retained more docosahexaenoic acid than eicosapentaenoic acid in the liver, suggesting a bioconversion of this fatty acid to intermediate fatty acids. Replacement of FO with PO significantly regulated genes controlling both fatty acid synthesis and catabolism pathways, potentially related to a higher percentage of monounsaturated fatty acids, in the livers of fish fed these diets. The results demonstrated that diet composition significantly altered the lipid metabolism in barramundi and that there was a balance between direct dietary effects and endogenous synthetic capacity.     

Preliminary study to evaluate the effects of dietary bile acids on growth performance and lipid metabolism of juvenile genetically improved farmed tilapia (Oreochromis niloticus) fed plant ingredient‐based diets

A 9‐week feeding experiment was conducted to investigate the effects of dietary bile acids (BAs) on juvenile genetically improved farmed tilapia (GIFT) (Oreochromis niloticus) based on the evaluations of growth performance and parameters relevant to lipid metabolism. Each of five vegetable protein‐based diets containing BAs at a level of 0, 0.05, 0.15, 0.45 or 1.35 g/kg diet was fed to three replicates with 40 fish (8.2 g per fish). The results showed that weight gain (WG) increased significantly with the increase in BAs from 0 to 0.15 g/kg diet and then decreased significantly at a higher BA supplementation. Dietary BAs significantly reduced the crude lipid content in the whole body, muscle and liver tissue of GIFT. Fish fed diet with 1.35 g BAs/kg diet developed serious nuclear migration and vacuolization in hepatocytes. Gall bladder appeared to contain white solid and has fragile capsules. Dietary BA supplementation had significant effects on serum biochemical indices and activities of lipid metabolism enzymes in liver and intestine. In conclusion, dietary bile acid supplementation (0.15 g/kg) can facilitate the lipid metabolism and therefore promote the growth of tilapia. However, overdosed dietary BAs induced gallstone development, disrupted lipid metabolism and depressed the growth performances of GIFT.     

Effect of dietary protein/carbohydrate ratio on activities of hepatic enzymes involved in the amino acid metabolism of Nile tilapia, Oreochromis niloticus (L.)

This study investigated the influence of different dietary protein/carbohydrate ratios on activities of enzymes involved in the amino acid metabolism as well as on growth performance and body composition of Nile tilapia (Oreo- chromis niloticus). Fish were fed semi-synthetic diets differing in their protein/carbohydrate ratio. The diets were formulated to be isolipidic and isoenergetic (on the basis of metabolizable energy). Fish were reared individually. After a prefeeding phase, tilapia were randomly assigned to three groups and were fed the experimental diets at a relatively low level. The study lasted 9 weeks. Proximate composition, gross energy content, and activities of aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) in the liver of fish were determined. While the mean growth rate and feed conversion efficiency did not differ significantly among the feeding groups, the body composition showed significant differences. The dietary protein/carbohydrate ratio had no significant effect on the protein and energy gain, but the lipid gain was significantly higher in tilapia fed the low-protein diet. The activities of ASAT and ALAT per gram of liver and per gram of soluble protein were significantly increased in fish fed the high-protein diet. There was a significant positive correlation between the activities of ASAT and ALAT. The activities of both enzymes in the liver were significantly higher in fish with a higher protein gain. Measuring the activities of enzymes involved in the amino acid metabolism can provide more information about the metabolic utilized dietary protein.     

The effect of hepatic passage on postprandial plasma lipid profile of rainbow trout (Oncorhynchus mykiss) after a single meal

For the first time, pre‐ and post‐hepatic plasma lipid profiles were monitored following a single meal in a free‐swimming, non‐anaesthetized fish. Rainbow trout (Oncorhynchus mykiss; 700–1500 g; 10 °C) were equipped with cannulae in the dorsal aorta (DA) and hepatic portal vein (HPV). Simultaneous blood samples, taken from both cannulae at 0, 3, 6, 12, 24 and 48 h postprandial, revealed the time course of the plasma lipid profiles following a single meal (1% of body mass). Primarily monounsaturated fatty acids with the exception of 18:1n ? 9, increased significantly from baseline by 12 h postprandial without greatly affecting total plasma lipid concentrations. Total plasma lipids then showed a small peak at 24 h postprandial, coinciding with a peak in triacylglycerols. We conclude that assimilation of lipids from the digest into the plasma is slower than reported for proteins and carbohydrates in the same species. Furthermore, as there were no significant differences between the HPV and DA, no measurable effect of hepatic passage on plasma lipid levels was resolved. Therefore, we also conclude that, in contrast to that in higher vertebrates, hepatic passage does not seem to have a major role in rainbow trout for modulating the postprandial plasma profile of lipids.     

褶皱臂尾轮虫土池低盐度培育及其脂肪酸营养评价

2003年4～5月利用低盐度(12)河口水在上海崇明进行了轮虫土池培育实验,并对其脂肪酸营养进行了分析和评价。经过33d培养,结果表明,(1)只要管理得当,低盐度、自然水温(平均水温为18.2℃)条件,土池培育轮虫可以实现持续稳定供应,采收时间、每日采收量和亩总产量分别达到28～29d、9.2kg/667m2·d和259kg/667m2,最高密度可达45个/ml;(2)敌害生物和饵料条件是土池培育轮虫持续稳产的关键因素;(3)土池培育轮虫EPA、DHA、AA等HUFA含量高于酵母和微绿球藻培育的轮虫,因此土池培育轮虫的营养价值好,适用于海水苗种培育。     

Effect of Artificial Diets on Growth,Survival and Condition of Adult Cuttlefish, <Emphasis Type="Italic">Sepia officinalis</Emphasis> Linnaeus, 1758

The effects of artificial diets on growth and body condition of adult cuttlefish, Sepia officinalis were tested in two experiments. Supplemented prepared diets (fish myofibrillar protein concentrate) were fed during a 30-day and a 21-day experiments. Growth, feeding rate and food conversion of group-reared cuttlefish were analyzed. The first of these experiments tested four artificial diets, made with increasing levels of lysine, on adult cuttlefish. According to the chemical analysis, diets 1–3 had limiting concentrations of lysine and other essential amino acids (compared to mantle composition of the cuttlefish), while diet 4 was the only one where almost all essential amino acids were present in concentrations similar or higher than the ones present in cuttlefish mantle. A second experiment was conducted by isolating 16 adult cuttlefish individually, and feeding them the same four artificial diets, in order to obtain individual data. During Experiment 1, only the diet with the best chemical score (diet 4) produced growth (p < 0.05), with a mean instantaneous growth rate (MIGR) of 0.30% wet body weight (BW) d⁻¹. Similarly, individually reared cuttlefish fed diet 4 produced the highest IGR’s (0.26, 0.38 and 0.48% BW d⁻¹) and grew larger (p < 0.01). Comparison of cuttlefish fed the artificial diets vs. thawed shrimp and unfed cuttlefish indicated that cuttlefish fed the artificial diets were in an intermediate state. Growth rates obtained with the artificial diets (<0.4% BW d⁻¹) were considerably lower compared to natural prey, live or frozen, reported by other authors.     

海蜇和沙蜇的氨基酸分析

海蜇和沙蜇是同属于腔肠动物门的大型食用水母 ,分为伞部和口腕部两部分。为了进一步开发利用海蜇和沙蜇资源 ,本文用氨基酸自动分析仪测定了其各部位的氨基酸种类和含量 ,并对其营养价值作了初步评价。结果表明 :海蜇和沙蜇中均含有 18种氨基酸 ,其中必需氨基酸 7种 ,含量分别占海蜇口腕部、海蜇伞部、沙蜇口腕部、沙蜇伞部中氨基酸总量的 2 6 .6 2 %、2 6 .6 6 %、31.0 4 %、36 .2 0 %。