Case study on eye abnormalities in tank-reared hybrid walleyes (Sander vitreus×S. canadensis)     

Mary Ann Garcia-Abiado  Michael Penn  & Konrad Dabrowski 《Aquaculture Research》2006,37(5):443-448

Hybrid walleye is important for recreational fisheries and is a potential aquaculture species in the north central region of the United States. Stress related to intensive culture conditions has been documented to cause eye lesions in fish. Finfish eyes do not have eyelids, hence the cornea is permanently exposed to mechanical damage and toxic substances. We documented various disorders of the eye in juvenile hybrid walleyes reared in a flow‐through tank system. Abnormalities include exophthalmia, enophthalmia, unilateral loss of globe and bilateral loss of globe. These lesions negatively affected body weight, specific growth rate and condition factor of hybrid walleyes reared in tanks.  相似文献   

Administration of gulonolactone does not evoke ascorbic acid synthesis in teleost fish     

Konrad Dabrowski 《Fish physiology and biochemistry》1991,9(3):215-221

Evidence is presented that for common carp (Cyprinus carpio L.), intraperitoneal injection of L-gulonolactone, a precursor of ascorbic acid synthesis in the D-glucuronic acid pathway, does not result in an increased concentration of ascorbate in tissue. Control fish injected with an equimolar amount of ascorbic acid have shown a significant increase in ascorbic acid concentration in the kidney, hepatopancreas, plasma and spleen. The ascorbate status in the carp body,i.e., the ascorbate nutritional history, produced significant differences in ascorbate withdrawal from circulation and probably in the catabolic rate. Acute fasting decreased ascorbate uptake into tissues as compared to fish fed a diet lacking ascorbate. Intraperitoneally injected ascorbate affects common carp being fed a diet containing 295 mg of total ascorbic acid kg^–1 by causing tissue to become saturated with vitamin C, similar to the tissues in the group undergoing acute fasting. There was no gulonolactone oxidase activity in the hepatopancreas of the common carp. These results suggest that the metabolic rate induced by feeding is the primary factor regulating ascorbate requirement.  相似文献   

Mouth size and predicted food size preferences of larvae of three cyprinid fish species     

Konrad Dabrowski  R. Bardega 《Aquaculture (Amsterdam, Netherlands)》1984,40(1):41-46

Mouth size was examined in larvae and juveniles of three cyprinid fish species: grass carp (Ctenopharyngodon idella Val.), silver carp (Hypophthalmichthys molitrix Rich.) and bighead carp (Aristichthys nobilis Rich.). A linear relationship was found between mouth size and the total length of fish, from the initial exogenous feeding stage up to 20–30 mm. Based on the mouth size, the size of the prey which could be consumed was calculated assuming 45° of mouth opening for optimum prey width and 90° for maximum prey width. Food particle size considered to be suitable for commencement of feeding amounted to 50–90 μm for silver carp larvae, 90–150 μm for grass carp larvae and 150–270 μm for bighead carp larvae. These criteria can be applied to moving rotifiers and nauplii as well as to the motionless particles of compound, dry diets.  相似文献   

Expanding the utilization of sustainable plant products in aquafeeds: a review   总被引：9，自引：0，他引：9  

Delbert M Gatlin III    Frederic T Barrows  Paul Brown  Konrad Dabrowski  T Gibson Gaylord  Ronald W Hardy  Eliot Herman  Gongshe Hu  Åshild Krogdahl  Richard Nelson  Kenneth Overturf  Michael Rust  Wendy Sealey  Denise Skonberg  Edward J Souza  David Stone  Rich Wilson  & Eve Wurtele 《Aquaculture Research》2007,38(6):551-579

Continued growth and intensification of aquaculture production depends upon the development of sustainable protein sources to replace fish meal in aquafeeds. This document reviews various plant feedstuffs, which currently are or potentially may be incorporated into aquafeeds to support the sustainable production of various fish species in aquaculture. The plant feedstuffs considered include oilseeds, legumes and cereal grains, which traditionally have been used as protein or energy concentrates as well as novel products developed through various processing technologies. The nutritional composition of these various feedstuffs are considered along with the presence of any bioactive compounds that may positively or negatively affect the target organism. Lipid composition of these feedstuffs is not specifically considered although it is recognized that incorporating lipid supplements in aquafeeds to achieve proper fatty acid profiles to meet the metabolic requirements of fish and maximize human health benefits are important aspects. Specific strategies and techniques to optimize the nutritional composition of plant feedstuffs and limit potentially adverse effects of bioactive compounds are also described. Such information will provide a foundation for developing strategic research plans for increasing the use of plant feedstuffs in aquaculture to reduce dependence of animal feedstuffs and thereby enhance the sustainability of aquaculture.  相似文献   

The importance of soil microbial activity for the supply of iron to sorghum and rape   总被引：2，自引：0，他引：2  

Evan Rroo  Harald Kosegarten  Fatos Harizaj  Jafargholi Imani  Konrad Mengel 《European Journal of Agronomy》2003,19(4):487-493

It is generally accepted that soil microorganisms play an important role in producing siderophores which enhance the availability of soil Fe to higher plants. There is not much direct experimental evidence to support this supposition, however, because it is difficult to grow plants under sterile conditions over long periods. The object of this investigation was to test whether a sterile soil medium impairs Fe translocation from the soil to plant roots. The plant species selected are of agronomical importance, namely rape (Brassica napus L.) and sorghum (Sorghum bicolor L.). The latter a graminaceous species which is able to excrete phytosiderophores from the roots into the soil which allows Fe to be mobilized and transported to plant roots. Sorghum and rape were grown for 18 and 21 days, respectively, in a non-sterile soil (control) and in the same soil which was sterilized before plant cultivation. In a further treatment, the sterile grown rape plants were supplied with Fe EDDHA 1 week before harvest in order to test whether a poor growth of plants grown in the sterile soil was caused by an insufficient Fe supply. Plants cultivated on the sterile soil were significantly retarded in root and shoot growth. This was especially true for rape which produced very small leaves. Plants responded immediately to the Fe addition which induced a vigorous growth. This clearly shows that the poor growth in the sterile soil was caused at least in part by an insufficient Fe supply. In neither plant species was yellowing of young leaves observed as a symptom typical of insufficient Fe supply. From this follows that retardation of plant growth is a more sensitive indicator of an insufficient Fe supply than is yellowing of young leaves at least for rape and sorghum. This finding is of agronomical importance since a reduced growth because of insufficient Fe supply is much more difficult to identify as Fe deficieny than Fe chlorosis (yellow leaves). Iron concentrations in roots and leaves of the sterile grown plants were significantly lower than the corresponding concentrations in the non-sterile grown plants. From these findings it can be concluded that soil microbial activity is essential for Fe acquisition by soil-grown rape. Similarily, sorghum which is able to release siderophores from the roots, requires soil microbial activity to ensure satisfactory Fe supply.  相似文献   

Use of Relief Contrast® Objective to Improve Sperm Morphometric Analysis by Isas® Casa System in the Ram     

JL Yániz  S Capistrós  S Vicente‐Fiel  C Soler  M Núñez de Murga  P Santolaria 《Reproduction in domestic animals》2013,48(6):1019-1024

The aim of this study was to develop a new method for morphometric assessment of the sperm head and acrosome in the ram. Ejaculates from 10 adult males were collected using an artificial vagina. For each ejaculate, 10 semen smears were prepared, air‐dried and divided (in pairs) into the following five treatment groups: (i) washed in distilled water and allowed to dry without further processing (DRY); (ii) fixed in 50% methanol (MET); (iii) fixed in 2% glutaraldehyde (GLUT); (iv) fixed and stained with Hemacolor^® (HEM) and (v) fixed and stained with SpermBlue^® (SB). The prepared slides were examined with a 40 × Relief Contrast^® objective (RC) and processed with ISAS^® commercial software. The use of RC optics increased the contrast between acrosome and sperm head, allowing capture and morphometric analysis by ISAS of sperm heads and the acrosome, even in non‐stained samples. MET and GLUT groups resulted in a lower number of acceptable, that is, correctly delineated, sperm heads than those in the SB, and SB and HEM groups, respectively (p < 0.05). The higher proportion of sperm discarded in MET and GLUT groups may be explained by a higher presence of artefacts. For the majority of the primary morphometric parameters of the sperm head and the acrosomal area, the relationship between treatments was the following: GLUT> HEM≥ MET≥ SB> DRY. When studying the proportion of the sperm head covered by the acrosome, the relation between treatments was: MET> DRY = GLUT = SB> HEM. It was concluded that the new method for sperm morphometric assessment allows the simultaneous assessment of sperm head and acrosome in the ram by the first time, even in unprocessed semen smears.  相似文献   

Influence of the FecXR Allele in Heterozygous Ewes on Follicular Population and Outcomes of IVP and ET using LOPU‐Derived Oocytes     

B Lahoz  JL Alabart  J Folch  P Sánchez  E Echegoyen  MJ Cocero 《Reproduction in domestic animals》2013,48(5):717-723

Ewes heterozygous for the FecX^R allele (R+) in the bone morphogenetic protein 15 (BMP15) gene display increased ovulation rate and prolificacy. Besides this phenotypic advantage, the influence of the FecX^R allele on follicle number and size, oocyte competence and in vitro production (IVP) remains undefined. With these aims, 8 R+ and 8 wild‐type (++) ewes were subjected to 2 laparoscopic ovum pick‐up (LOPU) trials (four sessions per trial; two with and two without FSH) and subsequent IVP and fresh embryo transfer. All follicles >3 mm were punctured (n = 1673). Genotype did not significantly affect the number of punctured follicles per ewe and session (10.4 and 10.2 in R+ and ++ untreated ewes, 17.4 and 14.3 in R+ and ++ FSH‐treated ewes, respectively), but follicular diameter of R+ ewes was significantly reduced compared with ++ ewes (?0.2 mm in untreated and ?0.8 mm in FSH‐treated ewes; p < 0.01). R+ ewes showed higher recovery rate and increased numbers of total and suitable cumulus–oocyte complexes for in vitro maturation (IVM). Similar rates of day 8 blastocysts were observed in R+ (36.1%, 147/407) and ++ (32.6%, 100/307) ewes, but the final output of day 8 blastocysts per ewe and session was higher in R+ ewes (+0.75; p < 0.005), without differences in survival rate at birth of the transferred embryos (40.4%, 21/52 vs 36.4%, 16/44, respectively). In conclusion, a higher number of oocytes proven to be competent for in vitro development and embryo survival after transfer are recovered from R+ ewes, despite the lower mean size of their follicles at puncture.  相似文献   

Implications of input estimation,residue quality and carbon saturation on the predictive power of the Rothamsted Carbon Model     

Felix Heitkamp  Matthias Wendland  Konrad Offenberger  Gerhard Gerold 《Geoderma》2012

Effects of fertilisation and cropland management on soil organic carbon (SOC) dynamics can be assessed best in long-term experiments. Using data from the long-term fertilisation experiment in Puch, Germany (part of the series “Internationale Organische Stickstoff Dauerversuche”, IOSDV), we tested the performance of the Rothamsted Carbon Model 26.3 (RothC). The objectives of this work were: (i) quantify the C-input and the efficiency of SOC stabilisation, (ii) test the performance of different input estimates on predictive power of the RothC and (iii) test implementations of residue quality and C-saturation on model predictions. The experiment is a full-factorial strip design, the factors being “organic amendment” and “level of N-fertiliser”. Each treatment was replicated three times. The crop rotation is silage maize–winter wheat–winter barley. Five levels of the factor “organic amendment” were considered: (i) CON: no organic amendment; (ii) SLU: slurry application (on average 0.8 Mg C ha^? 1 year^? 1); (iii) FYM: application of farmyard manure (30 to 40 Mg ha^? 1 fresh mass every third year to maize, on average 1.0 Mg C ha^? 1 year^? 1); (iv) STR: straw incorporation after harvest of wheat and barley (depending on straw yield on average 0.7 to 2.2 Mg C ha^? 1 year^? 1); (v) STSL: slurry application plus straw incorporation (on average 1.1 to 2.4 Mg C ha^? 1 year^? 1). All treatments (including CON) were combined with five different levels of N-fertilisation (N0 to N4), whereas N0 was nil N application and N4 averaged 177 kg N ha^? 1 year^? 1. N-rates increased gradually and differed depending on the crop. Starting values for SOC stocks (Mg ha^? 1) were measured in 1983 as a mean among N-rates for organic amendment treatments (CON: 42; SLU: 39.8; FYM: 40.5; STR 39.8; STSL: 40.5). SOC stocks (0–25 cm) in 2004 (35.5 to 46.6 Mg C ha^? 1) were in the order STSL > FYM = SLU > STR = CON (p ≤ 0.001). However, slightly different starting values indicated a higher loss of SOC after 21 years in the CON (11–14%) compared to the STR treatments (1–10%). Effect of N-rate was not significant. The observed relation between change of SOC and C-input was quadratic (Y_O = ? 13.4 + 7.5x ? 0.9x²; R² = 0.74, p ≤ 0.001), which contrasted the linear relationship predicted by RothC (Y_P = ? 12.9 + 5.5x; R² = 0.97, p ≤ 0.0001). Serious deviation between observed and predicted relationship occurred above C-inputs of 2.5 Mg C ha^? 1 year^? 1. Mechanistic explanation (e.g. C-saturation or increased mineralisation by N-fertilisation) for the observation needs further exploration, but implication on regional estimates for C-accumulation for different cropland management scenarios is obvious: potential gain in SOC storage by increasing C-inputs may be overestimated, at least under conditions of the Puch site. Independent model predictions (i.e. no parameter adjustment and independent estimation and measurement of C-input) were successful for treatments without straw incorporation (CON, SLU, FYM). Using a regression between crop yields and crop residue input yielded better results than using a constant belowground-to-aboveground biomass ratio. SOC stocks of treatments STR and STSL were seriously overestimated by the model. Using a higher decomposability of crop residue improved result only marginally and required the change of a standard parameter. Using a simple implementation of C-saturation improved predictions for STR and STSL but failed to simulate dynamics in all other treatments. Overall, our results showed that it is important to recognise that relation between SOC change and C-input is not necessarily linear. However, the RothC model predicted SOC dynamics well at lower input levels. Observation that a regression equation for input estimation is superior to a constant biomass ratio for modelling purposes has to be tested further. An implementation of residue quality or saturation capacity in the RothC model may be promising for a better mechanistic understanding of SOC dynamics. However, this requires careful calibration and will increase the number of parameters to be fitted.  相似文献   

Spatial pattern formation in an insect host-parasitoid system     

JL Maron  S Harrison 《Science (New York, N.Y.)》1997,278(5343):1619-1621

Spatial models in ecology predict that populations may form patchy distributions within continuous habitats, through strong predator-prey or host-parasitoid interactions combined with limited dispersal. Empirical support of these models is provided. Parasitoids emanating from a population outbreak of tussock moths (Orgyia vetusta) suppressed the growth of nearby experimental populations of the moth, while experimental populations farther away were able to grow. This result explains the observed localized nature of tussock moth outbreaks and illustrates how population distributions can be regulated by dynamic spatial processes.  相似文献   

Radar characteristics of birds in flight. Radar tracking of known single birds indicates a characteristic radar "signature"     

T G Konrad  J J Hicks  E B Dobson 《Science (New York, N.Y.)》1968,159(812):274-280

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