Growth performance and body composition of pike perch (Sander lucioperca) fed varying formulated and natural diets     

Carsten Schulz  Steffen Günther  Manfred Wirth  Bernhard Rennert 《Aquaculture International》2006,14(6):577-586

To assess the effect of dietary composition on growth performance and body composition of pike perch (Sander lucioperca), fingerlings with an initial body weight of 1.36 g (just trained to accept formulated feed) were fed three experimental diets in triplicate for 90 days. Two feeding groups were fed with formulated diets (CD, CD+7) containing varying levels of crude lipid (CL) of 14.65% and 21.94% dry matter (d.m.) with crude protein (CP) levels of 59.73% and 56.56%, and one feeding group was fed a natural diet (chironomids, CP = 65.93% d.m.; CL = 7.20% d.m.). Furthermore, pike perch of the same age caught in different natural habitats were analysed to determine their naturally fluctuations in body composition. Specific growth rate (SGR; CD = 3.36, CD+7 = 3.47) and feed conversion ratio (FCR; CD = 1.02, CD+7 = 0.93) of fish fed formulated diets did not differ significantly with rising dietary lipid content, due to high variability within the individuals of each feeding groups. In contrast, pike perch fed with chironomids showed a significantly lower SGR of 2.49 and higher FCR of 2.37 (on a dry matter basis). Body composition of pike perch fed formulated diets was affected by dietary composition and showed increased lipid contents [CD=6.25% original matter (o.m.), CD+7 = 9.00% o.m.] with rising dietary lipid levels. Pike perch of CD and CD+7 feeding groups showed significant increased hepatosomatic indices (HSIs) of 1.99 and 2.05 in contrast to fish fed chironomids with HSI of 1.11. Fish caught in the different natural habitats were characterised by low body lipid and dry matter contents of 0.64–1.88% o.m. and 21.08–23.75% o.m. Higher lipid incorporation of fish fed with formulated diets accompanied with poor benefit on growth performance at higher dietary lipid content indicated that pike perch ability to utilise lipids is low when dietary crude protein content is higher than 56.56%.  相似文献   

Hormone Profiles of Captive Striped Bass Morone saxatilis During Spermiation, and Long-Term Enhancement of Milt Production   总被引：2，自引：0，他引：2  

Constantinos C.  Mylonas Yonathan  Zohar L. Curry  Woods III Peter  Thomas Rüdiger W.  Schulz 《Journal of the World Aquaculture Society》1998,29(4):379-392

Abstract— Plasma profiles of reproductive and thyroid hormones were studied in captive striped bass Morone saxatilis during an 11-wk period encompassing the spawning season, and the effect of a sustained-release gonadotropin-releasing hormone agonist (GnRHa)-delivery system (GnRHa-implant) on milt production was evaluated. The highest percentage of spermiating fish was observed between mid-April and mid-May, and mean total expressible milt ranged from 3.5 to 6.0 mL/kg. Plasma gonadotropin II (GtH II) increased significantly, though inconsistently, during the spermiation period, whereas testosterone and 11-ketotestosterone levels declined continually. Plasma 17,20β-dihydroxy-4-pregnen-3-one and 17,20β,21-dihydroxy-4-pregnen-3-one remained low and unchanged during the peak of the spermiation period, while thyroid hormones were high and fluctuated without exhibiting a trend consistent with spermiation. The observed endocrine profiles suggest that captivity can diminish plasma GtH II and triiodothyronine levels in striped bass. Transfer of spermiating males from large holding tanks to small spawning tanks reduced total expressible milt after 14 d, but treatment with a GnRHa-implant restored milt volume, presumably due to the prolonged elevation of plasma GnRHa and GtH II induced by the GnRHa-implant. Also, treatment with the GnRHa-implant induced a two- to four-fold elevation of expressible milt for at least 20 d compared to control fish, while resulting in only a 5 to 15% decrease in sperm density. It appears that captivity and hatchery operations can diminish milt production in striped bass, and that GnRHa-delivery systems, via sustained elevation of plasma GtH II, can induce long-term enhancement in milt volume without affecting sperm density greatly.  相似文献   

Development options of natural habitats in a post‐mining landscape     

F. Schulz  G. Wiegleb 《Land Degradation \u0026amp; Development》2000,11(2):99-110

Rehabilitation of the post‐mining landscape of Lower Lusatia (Brandenburg, Germany) represents a complex problem: 85 per cent of this area is currently being recultivated for forests or agriculture and 15 per cent is reserved for nature development. After mining, soil conditions are dry, acidic and nutrient poor. The ‘LENAB’ project aimed at conservation strategies and management options for natural habitats. Two competing basic motives of nature conservation on a small or medium scale were defined: (1) close‐to‐naturalness (allowing natural dynamics to take place without human interference) and (2) biodiversity (selective species and habitat protection). An overall strategy for sustainability of a cultural landscape can only be applied to the entire post‐mining landscape. The application of the two basic motives leads to different management options; this is illustrated by two important vegetation types. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Correction to: Maintenance requirement and utilisation efficiency of energy and protein for ongrowing pikeperch (Sander lucioperca (L.))     

Zimmermann  J.  Steinberg  K.  Hund  C.  Meyer  S.  Schulz  C. 《Aquaculture International》2022,30(4):2199-2199

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