纳米硒添加剂对褐牙鲆生长性能、耗氧率及排氨率的影响

在饲料中通过喷洒的方式添加液体纳米硒,测定不同浓度液体纳米硒对褐牙鲆生长性能、耗氧率及排氨率的影响。结果表明:与投喂基础饲料的对照组相比,饲料中添加纳米硒的试验组褐牙鲆的终末体质量、特定生长率及增重率显著提高,其中10 m L/kg组增长最为显著;肝体比、脏体比及肠体比对照组与试验组无显著差异;添加纳米硒可以增强褐牙鲆的耗氧率及排氨率,耗氧率在10 m L/kg时达到最高,排氨率在20 mL/kg时达到最高。     

Rates of oxygen consumption and ammonia excretion of juvenile Eurasian perch Perca fluviatilis L.

The impact of feeding, fish size (body weight from 18.5 to 56.5 g) and water temperature (20 and 23 °C) on oxygen consumption (OC, mg O₂ kg^–1 h^–1) and ammonia excretion (AE, mg TAN kg^–1 h^–1) was studied in Eurasian perch held in recirculation systems. OC for both fed and feed-deprived (3 days) fish was higher at 23 °C (278.5 and 150.1 mg O₂ kg^–1 h^–1) than at 20 °C (249.3 and 135.0 mg O₂ kg^–1 h^–1; P < 0.01). AEs for both fed and feed-deprived fish were also significantly higher at 23 °C than at 20 °C (P < 0.001). Water temperature and fish size had a significant impact on the oxygen:feed ratio (OFR, kg O₂ kg^–1 feed fed day^–1) and ammonia:feed ratio (AFR, kg TAN kg^–1 feed fed day^–1; P < 0.001). Their average values at temperatures of 20 and 23 °C were 0.17 and 0.19 kg O₂ kg^–1 feed fed day^–1 and 0.009 and 0.011 kg TAN kg^–1 feed fed day^–1, respectively.     

山东省牛主要污染物产生量估算及环境效应研究

[目的]估算了山东省牛粪便的总量及其养分的负荷量和占当年排泄污染物的比例。[方法]根据2010年山东省和各地市牛存栏的行业和统计局两套数据和2012年行业数据,通过计算参数和估算的方法算出了牛粪产生总量。[结果]全省牛粪总共约在7000~9700万 t 之间,占当年所有畜禽粪便产生量的34.07%~37.37%之间,即三分之一以上。德州、济南两市单是牛粪便的土地承载量分别达到了29.7 t/hm2和27.4 t/hm2,接近了欧洲标准30 t/hm2的限量值。[结论]应该引起我们对全省牛业发展方式和发展战略的高度重视。     

Estradiol-17β-induced calcium uptake and resorption in juvenile rainbow trout,Oncorhynchus mykiss

Juvenile rainbow trout, Oncorhynchus mykiss, were injected with estradiol-17β (E₂) in order to study the source of extra calcium needed during vitellogenesis. E₂-treatment increased the calcium uptake from the external medium as well as calcium mobilization from muscle and scale. Judged by the increase in plasma protein-bound calcium levels, the E₂-induced increase in calcium uptake is an apparent over-mobilization of calcium, i.e., the calcium uptake of the fish is in excess of what is found bound to plasma proteins. As the calcium excretion and calcium space (calculated from free plasma calcium levels) were unaffected, the excess calcium is suggested to be incorporated into internal calcium stores. This implies that the systems regulating vitellogenesis and calcium balance are integrated on the mechanistic or endocrine level, and that E₂ causes calcium mobilization of a magnitude geared to the needs of the sexually maturing female.     

Effects of supplemental palygorskite instead of zinc oxide on growth performance,apparent nutrient digestibility and fecal zinc excretion in weaned piglets

The aim of this study was to determine the effects of dietary supplementation of palygorskite instead of zinc oxide (ZnO) on growth performance, apparent nutrient digestibility and zinc contents in serum and feces in weaned piglets. One hundred and sixty‐five piglets (28 days of age, 7.10 ± 0.86 kg) were allotted to five treatments on the basis of weight and sex. Each treatment included three replicates of 11 piglets. The piglets were fed the same basal diet supplemented with 0 mg/kg (control group), 1800 mg/kg, 2400 mg/kg, or 3000 mg/kg palygorskite or 2500 mg/kg ZnO for 28 days. There was no significant difference for incidence of diarrhea among the four treatments during the 0–14‐day feeding period. Compared with the control group, piglets offered diets supplemented with 1800 mg/kg palygorskite had higher (P < 0.05) average daily gain (ADG) and crude protein digestibility. Fecal digestibility of energy in 1800 mg/kg palygorskite and ZnO groups were higher (P < 0.05) than that in the control group. Both the zinc concentrations in serum and fecal zinc excretion in palygorskite groups and control group were all lower (P < 0.05) than that in the ZnO group. In conclusion, dietary supplementation with 1800 mg/kg palygorskite can improve growth performance and nutrient digestibility and can also decrease zinc excretion in feces in weaned piglets.     

盐度对大菱鲆幼鱼耗氧率和排氨率的影响

研究了大菱鲆(Scophamusmaximus)幼鱼由盐度34向低盐(盐度28、23、18、12、6)以及向高盐(盐度40)适应过程中代谢率的变化。结果表明:盐度改变后,各突变组大菱鲆幼鱼的耗氧率和排氨率都呈现出不同程度的逐渐升高趋势,随着盐度突变范围的增大,变化趋势更为明显。在突变后24h左右,各突变组大菱鲆幼鱼耗氧率出现高峰值,48h后恢复到突变前的水平,此时各实验组大菱鲆的耗氧率没有显著的差异性(P>0.05)。在突变后9～15h排氨率出现高峰值,48h后各组大菱鲆幼鱼的排氨率恢复到突变前的水平,此时各实验组大菱鲆的排氨率没有显著的差异性(P>0.05)。     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.     

Ammonia distribution and excretion in fish

This paper reviews the literature concerning ammonia production, storage and excretion in fish. Ammonia is the end product of protein catabolism and is stored in the body of fish in high concentrations relative to basal excretion rates. Ammonia, if allowed to accumulate, is toxic and is converted to less toxic compounds or excreted. Like other weak acids and bases, ammonia is distributed between tissue compartments in relation to transmembrane pH gradients. NH₃ is generally equilibrated between compartments but NH₄ ⁺ is distributed according to pH. Ammonia is eliminated from the blood upon passage through the gills. The mechanisms of branchial ammonia excretion vary between different species of fish and different environments, and primarily involves NH₃ passive diffusion and NH₄ ⁺/Na⁺ exchange. Water chemistry near the gill surface may also be important to ammonia excretion, but a more accurate measurement of the NH₃ gradient across the gill epithelium is required before a more detailed analysis of NH₃ and NH₄ ⁺ excretion can be made.     

Effect of dietary vitamin C supplementation on the oxygen consumption, ammonia-N excretion and Na/K ATPase of Macrobrachium nipponense exposed to ambient ammonia

The 96-h LC₅₀ of ammonia-N and the effects of dietary vitamin C on oxygen consumption, ammonia-N excretion and Na⁺/K⁺ ATPase activity of Macrobrachium nipponense exposed to ambient ammonia were investigated. The results showed that the 96-h LC₅₀ of ammonia-N was 36.6 mg l⁻¹ for the freshwater prawn, M. nipponense, at pH 8.0. When prawns were exposed to high ambient ammonia-N concentrations, the oxygen consumption rate increased and ammonia excretion decreased. Dietary vitamin C supplementation led to higher oxygen consumption and lower ammonia excretion. Na⁺/K⁺ ATPase activity increased with increased ambient ammonia-N exposure in the range of 0–18.3 mg l⁻¹, and then was reduced at ambient ammonia-N 36.6 mg l⁻¹. Na⁺/K⁺ ATPase activities of prawns fed a vitamin C-supplemented diet were significantly lower than those of prawns fed a diet which was not supplemented with vitamin C.     

Biochemistry and physiology of a family of eel natriuretic peptides

Three natriuretic peptides with similar structures were isolated from eels and their amino acid sequences determined; atrial natriuretic peptide (ANP) from atria, ventricular natriuretic peptide (VNP) from ventricles, and C-type natriuretic peptide (CNP) from brains. All three hormones were circulating in eel blood, and their plasma levels invariably decreased when eels were transferred from fresh water (FW) to seawater (SW). Eel ANP and VNP inhibited drinking in FW and SW eels. Eel ANP inhibited water and Na⁺ absorption by the intestine of SW eels. The potency of these ANP effects was 2–3 orders greater than those of other hormones which are known to have similar effects. Eel ANP and VNP induced antidiuresis but not antinatriuresis in FW eels. Eel ANP increased plasma cortisol level in SW eels but not in FW eels. The antidiuretic effect and the stimulation of cortisol secretion in eels are opposite to the ANP effects reported in mammals. These data suggest that ANP plays a complex role in the eel osmoregulation.

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Résumé Trois peptides natriurétiques présentant des structures similaires ont été isolés chez l'anguille et leurs séquences en acides aminés a été déterminées; le peptide atrial natriurétique (ANP) dans l'atria, le peptide ventriculaire natriurétique (VNP) dans les ventricules et le peptide natriurétique de type C dans le cerveau. Ces trois hormones sont présents dans le sang d'anguille et leur niveau plasmatique decroit invariablement quand les anguilles sont transférées d'eau douce en eau de mer. L'ANP et le VNP d'anguille inhibent l'action de boire chez les anguilles d'eau douce et d'eau de mer. L'ANP d'anguille inhibe l'absorption d'eau et de Na⁺ par l'intestin d'anguille en eau de mer. Ces effets de l'ANP sont 2 à 3 fois plus grands que ceux observés avec d'autres hormones qui sont connues pour avoir des effets similaires. L'ANP et le VNP d'anguille induisent l'antidiurèse mais pas l'antinatriurèse chez les anguilles d'eau douce. L'ANP d'anguille augmente chez ce poisson les niveaux de cortisol plasmatique en eau de mer mais pas en eau douce. L'effet antidiurétique et la stimulation de la sécrétion de cortisol chez l'anguille sont contraire aux effets de l'ANP observés chez les mammifères. Ces résultats suggèrent que l'ANP joue un role complexe dans l'osmorégulation de l'anguille.