Kritische Umweltbelastungen Landwirtschaft (Kul)‐Pflanzenschutzmittel‐ und Wachstumsregulatoreneinsatz

Im Rahmen einer Umweltverträglichkeitsbewertung werden quantifizierbare und kontrollfähige Kriterien des Pflanzenschutzmitteleinsatzes festgelegt und kritische Belastungen erarbeitet. Damit sollen sowohl Betriebsvergleiche ermöglicht als auch der Landwirtschaft ein Rahmen vorgegeben werden, der den tolerierbaren Bereich des Mitteleinsatzes absteckt. Mit Blick auf öffentliche Akzeptanzproblerne des Pflanzenschutzmitteleinsatzes sind neben potentiellen Umweltbeeinträchtigungen auch öffentliche Ängste in Bewertungsprozesse einzubeziehen. Die Kriterien Wirkstoffmenge, untersetzt nach Anwendungsgruppen, Mitteltoxizität und Ausbringungstechnologie könnten diesen Forderungen gerecht werden, da sie auf Minimierung der Wirkstoffmenge, Optimierung der Ausbringung und Auswahl mindertoxischer Mittel orientieren. Die kritische Belastung bildet somit nicht die Grenze zum umweltschädigenden, sondern zum unnötigen Bereich.     

Production of Oocytes of Nile Tilapia (Oreochromis niloticus) for In Vitro Fertilization via Hormonal Treatments

Only a few studies have described hormonal treatments for induction of synchronicity and gamete collection in Nile tilapia (Oreochromis niloticus), both important for assortative matings in breeding programmes and essential for polyploidy technologies. In this study, we compared the effectiveness of carp pituitary extract (CPE), Nile tilapia pituitary extract (TPE), human chorionic gonadotropin (hCG) and gonadotropin‐releasing hormone (GnRH) protocols on the induction of spawning and egg production in Nile tilapia. Among the hormonal treatments analysed, only hCG was effective for producing viable gametes for in vitro fertilization. To verify the viability of this hormonal treatment, hCG was tested using different doses (1000, 2000, 3000, 4000 and 5000 IU/kg) in a large number of females (208 animals) from two Nile tilapia lines. The results indicated that hCG doses between 1000 and 5000 IU/kg could be used to induce final oocyte maturation in Nile tilapia with collection of stripped oocytes. This is the first study to report differential reproductive responses to hormonal treatment between tilapia lines: line 1 was more efficient at producing eggs and post‐hatching larvae after hCG induction than line 2. In conclusion, we demonstrated that the hCG protocol may be applied on a large scale to induce final oocyte maturation in Nile tilapia. The development of a protocol for in vitro fertilization in Nile tilapia may aid in breeding programmes and biotechnological assays for the development of genetically modified lines of Nile tilapia.     

Dietary astaxanthin supplementation for hatchery‐cultured red king crab,Paralithodes camtschaticus,juveniles

We conducted large‐scale production trials in Seward, Alaska, USA to investigate effects of dietary astaxanthin supplementation on survival, growth and shell colouration of recently settled juvenile (C1–C4) red king crabs (Paralithodes camtschaticus). We supplemented a control diet of commercial crustacean feeds with astaxanthin, and fed these diets to juvenile king crabs at densities of 2000 and 4000 crabs m^?2 for 56 days. We assessed survival and growth by counting crabs and individually measuring carapace width and weighing crabs at the start and end of the experiment, and quantified crab colour (hue, saturation, brightness) in digital photographs. Diets containing astaxanthin had higher survival, suggesting that astaxanthin may provide nutritional or immune system benefits. Crabs had lower hue, higher saturation and lower brightness values when fed diets containing astaxanthin, suggesting that red king crab colouration is plastic and responds to diet. Astaxanthin is likely an important dietary component for hatchery or laboratory reared red king crab juveniles, and should be considered for aquaculture and other rearing of this and possibly other crustacean species.     

Effects of meiotic inhibitors and gonadotrophins on porcine oocytes in vitro maturation,fertilization and development

This study evaluated the effect of three reversible meiotic inhibitors (MINs) and their interaction with gonadotrophins (Gns) on the meiotic maturation and developmental competence of porcine oocytes. In experiment 1, the oocytes were matured for 22 hr in the presence or absence of dbcAMP (1 mM), cycloheximide (7 μM) or cilostamide (20 μM) with or without Gns, and for an additional 22 hr in the absence of MINs and Gns. At 22 hr of maturation, regardless of the presence of Gns, a higher proportion (p < .001) of oocytes cultured in the presence of MINs were effectively arrested at the germinal vesicle stage compared with the oocytes cultured without MINs. At 44 hr of maturation, the proportion of oocytes that reached MII was higher (p < .05) in groups with Gns compared with groups without Gns. In experiment 2, oocytes that were matured as in experiment 1 were inseminated and cultured for 7 days to evaluate fertilization parameters and blastocyst formation. Only oocytes from the dbcAMP + Gns group had higher (p < .05) efficiency of fertilization compared with the other treatment groups. The presence of dbcAMP during maturation also increased (p < .05) blastocyst formation and efficiency of blastocyst formation in both the presence and absence of Gns. These results indicate that the interaction of Gns with the tested MINs improved meiotic progression. In addition, regardless of supplementation with Gns, the presence of dbcAMP during the first maturation period increased and even doubled the capacity of oocytes to develop to the blastocyst stage.     

Azomethines of sec-butylamine for the control of penicillium decay of oranges

Imines, synthesised by the reaction of sec-butylamine (SBA, 2-amino-butane) with pentan-2-one, heptan-2-one, octan-2-one, undecan-2-one, benzaldehyde and 2-furaldehyde, were evaluated as vapour-phase treatments to prevent the infection of oranges by Penicillium digitatum. All the imines provided decay control equivalent to SBA when they were introduced into the fruit container at a rate equivalent to 16.4 mg SBA litre^?1 air volume. The carbonyl compound component of the imines, tested alone at a five-fold higher rate, did not reduce fruit decay. All the imines were stable in the gaseous state in dry air. The imines of pentan-2-one and undecan-2-one were hydrolysed rapidly in a humid environment, indicating that their action against P. digitatum was due to the release of SBA into the atmosphere around the fruit. The instability of the imines of the aliphatic ketones makes them unsuitable as generators of SBA in packages. The imines derived from benzaldehyde and 2-furaldehyde were stable in moist air, but were hydrolysed to a significant degree on moist filter paper, especially at pH < 7. These aromatic imines were absorbed from the atmosphere by the fruit and were hydrolysed rapidly in water, and in a buffer solution that represented the environment in fresh injuries on fruit. Apparently all the imines tested generated SBA in the fruit environment, and this SBA accumulated at potential infection sites, where it prevented the development of decay.     

Comparison of viability assays for Cryptosporidium parvum oocysts after disinfection

In order to test various viability assays for Cryptosporidium parvum oocysts were used to infect HCT-8 cells in vitro or baby mice. Infected cells were either stained with fluorescent anti-Cryptosporidium-antibody or lysed and subjected to C. parvum-specific PCR after 48 h. Titrations with infective oocysts were performed and compared to oocysts disinfected with Neopredisan for 2 h at varying concentrations. Caecal smears and histological sections from infected animals were examined in parallel. The number of foci of parasite development in vitro after immunofluorescent staining correlated well with the infection dose. PCR was less quantifiable and the results were not always reproducible, especially when low infection doses were used. Disinfection resulted in a dose-dependent reduction of oocyst infectivity when compared to the controls in all three assays. The infection of cells cultured in vitro with oocysts of C. parvum provides a suitable tool for the estimation of viability after treatment with chemical disinfectants. Immunofluorescence is easy to perform and gives quantitative results, while PCR-based detection of parasite DNA, although possible, requires the use of more sophisticated tools for quantification.     

Veterinary aspects of alveolar echinococcosis--a zoonosis of public health significance

Human alveolar echinococcosis (AE), caused by the metacestode stage of Echinococcus multilocularis, is a serious zoonosis which caused up to 100% lethality in untreated patients before the 1970s, when modern methods of treatment were not yet established. AE occurs in large areas of the northern hemisphere mostly with low country-wide prevalences, but high prevalences of up to 4% have been reported from small population groups in highly endemic foci, e.g. from China. AE includes many veterinary aspects which are the topic of this review. Recent studies have shown that E. multilocularis has a wider geographic range than previously anticipated. There is evidence for growing populations of red foxes (Vulpes vulpes) in some areas, for increasing invasion of cities by foxes and also for establishment of the parasite cycle in urban areas. These and other factors may lead to an increased infection risk for humans. Significant progress has been made in the development of sensitive and specific new techniques for the intra vitam and post mortem diagnosis of intestinal E. multilocularis infection in definitive hosts, notably the detection of coproantigen by enzyme-linked immunosorbent assay and of copro-DNA by PCR. Both tests can also be used for the identification of E. multilocularis in faecal samples collected in the environment. Recommendations are given for chemotherapy and chemoprophylaxis of the intestinal infection in definitive hosts. In recent years, infections with the metacestode stage of E. multilocularis have not only been diagnosed in humans in several regions, including at least eight countries in central Europe, but also in animal species which do not play a role in the transmission cycle (wild and domestic pigs, dogs etc.). From 1987 to 2000 our group in Zurich has diagnosed 10 cases of AE in dogs and 15 in captive monkeys. In 2 dogs, concurrent infections of the intestine and of the liver with adult and larval stages of E. multilocularis, respectively, were observed for the first time. Clinical data are presented, and methods of diagnosis and treatment (surgery, chemotherapy) are described. Furthermore, small liver lesions caused by E. multilocularis were diagnosed in 10% of 90 slaughter pigs, and 2.9% of 522 breeding sows had specific serum antibodies against parasite antigens. In view of the unpredictable epidemiological situation, all possible measures for preventing E. multilocularis infections in humans and in domestic animals should be initiated by the veterinary and health authorities.     

Copper status of ewes fed increasing amounts of copper from copper sulfate or copper proteinate

The Cu status of mature, crossbred ewes fed two sources (CuSO4 vs. Cu proteinate) and three levels (10, 20, or 30 mg/kg) of dietary Cu was determined in a 73-d feeding trial. Ewes (n = 30) were fed a basal diet containing rice meal feed, cottonseed hulls, cottonseed meal, meat and bone meal, cracked corn, and vitamin-mineral supplements at 2.5% of BW to meet NRC requirements for protein, energy, macrominerals, and microminerals, excluding Cu. The basal diet contained 5 mg/kg Cu, 113 mg/kg Fe, .1 mg/kg Mo, and .17% S. Copper sulfate or Cu proteinate was added to the basal diet to supply 10, 20, or 30 mg/kg of dietary copper in a 2x3 factorial arrangement of treatments. Ewes were housed in 3.7- x 9.1-m pens in an open-sided barn. Blood samples were collected on d 28 and 73. Ewes were slaughtered on d 74, and liver and other tissues were collected to determine Cu concentrations. An interaction (P = .08) occurred between source and level for liver Cu. The interaction existed due to an increase in liver Cu concentrations when ewes were fed increasing dietary Cu from CuSO4 but not when fed Cu proteinate diets. There was no source x level interaction (P>.10) for the blood constituents measured. On d 73, plasma ceruloplasmin activity was greater (P<.05) in ewes fed Cu proteinate than in those fed CuSO4 (33.1 vs. 26.8 microM x min(-1) x L(-1)). Increasing the concentration of dietary Cu did not affect (P>.10) plasma ceruloplasmin. Packed cell volume (PCV), red blood cell count (RBC), white blood cell count, whole blood hemoglobin (wHb), plasma hemoglobin, and plasma Cu were similar between sources of Cu. Ewes fed 20 mg/kg Cu had lower (P<.05) PCV, RBC, and wHb than those fed 10 or 30 mg/kg Cu diets. Feeding up to 30 mg/kg Cu from these sources did not cause an observable Cu toxicity during the 73-d period.