Production of Lambs After the Transfer of Fresh and Cryopreserved in vitro Produced Embryos from Prepubertal Lamb Oocytes and Unsorted and Sex-sorted Frozen-thawed Spermatozoa

Cumulus-oocyte complexes from hormone-stimulated 3-4-week-old (n=43) and 6-7-week-old (n=12) prepubertal lambs were matured in vitro and incubated with unsorted, or X- or Y-spermatozoa separated with a high-speed cell sorter (SX MoFlo)frozen-thawed. Presumptive zygotes were then cultured to the blastocyst stage, and transferred to recipients fresh or after cryopreservation (frozen). Oocyte cleavage was higher (p <0.05) with unsorted (515/926, 55.6%) than X- or Y-spermatozoa (261/672, 38.8% and 229/651, 35.2%, respectively) and blastocyst formation (% zygotes) by Day 9 of in vitro culture was lower (p <0.05) for X- (102/261, 39.1%) than unsorted spermatozoa (249/515, 48.3%), but did not differ between Y-spermatozoa (103/229, 45.0%) and unsorted spermatozoa, or between X- and Y-spermatozoa (p >0.05). For fresh embryos, survival to term was 50.0% (3/6) for unsorted, 0.0% (0/6) for X- and 16.7% (1/6) for Y-spermatozoa-derived embryos (p >0.05), and for frozen embryos was 4.0% (2/50) for unsorted, 9.1% (2/22) for X- and 2.9% (1/34) Y-spermatozoa-derived embryos (p >0.05). Of the two lambs born from X-spermatozoa-derived embryos, one was female (50%), and from the two Y-spermatozoa-derived lambs, both were male (100%), demonstrating that lambs can be produced after the transfer of fresh and cryopreserved IVP embryos derived from prepubertal lamb oocytes and frozen-thawed sex-sorted sperm.     

Proportionality principle revisited – relationship between application rates and pesticide residue concentrations in food commodities

BACKGROUND

The proportionality principle has been broadly used for over 10 years in regulatory assessments of pesticide residues. It allows extrapolation of supervised field trial data conducted at lower or higher application rates compared to the use pattern under evaluation by adjustment of measured concentrations, assuming direct proportionality between the rates applied and the resulting residues. This work revisits the principle idea by using supervised residue trials sets conducted under identical conditions but with deviating application rates. Four different statistical methods were used to investigate the relationship between application rates and residue concentrations and to draw conclusions on the statistical significance of the direct proportionality assumed.

RESULTS

Based on over 5000 individual trial results, the assumption of direct proportionality was not confirmed to be statistically significant (P > 0.05) using three models: direct comparison of application rates and residue concentrations ratios and two linear log-log regression models correlating application rate and residue concentration or only residue concentrations per se. In addition, a fourth model analysed deviations between expected concentrations following direct proportional adjustment and measured residue values from corresponding field trials. In 56% of all cases, the deviation was larger than ±25%, which represents the tolerance usually accepted for the selection of supervised field trials in regulatory assessments.

CONCLUSION

Overall, the assumption of direct proportionality between application rates and resulting residue concentrations of pesticides was not statistically significant. Although the proportionality approach is highly pragmatic in regulatory practice, its use should be considered carefully on a case-by-case basis. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Laboratory investigation of the chemical disinfection against different developmental stages of the housefly (Musca domestica Linnaeus, 1758)

Possibilities for disinfection of the developmental stages from the housefly (Musca domestica) were investigated under laboratory conditions. The developmental stages (eggs, larvae I, II, III, pupae and adults) were sprayed with solutions of disinfectants on the basis of p-chlorine-m-cresol and o-phenylphenol at different concentrations (0.025%-3%). The effectiveness of both disinfectants was established by determining the emergence rate of eggs and pupae and of the live evidence of larvae and adults. Transmission electron microscopic investigations of the cover of the eggs revealed the bactericidal effect of both disinfectants. These results show the necessity of extending its use also to noxious arthropods.     

Hausrattennachweise (Rattus rattus L.) in bewohnten Wohnh?usern in Magdeburg

Storehouses and mills in the Magdeburg region are known to be infested with black (ore house) rats. In residential buildings, however, house rats (Rattus rattus L.) have not been detected for at least 20 years. Therefore, it was of much interest for the expert to note that this rat species had been seen in two occupied residential buildings (a refurbished old building and a terraced house). It has been suspected for a longer time that black rats can be found in certain residential buildings in towns or even cities.     

Erfolgreiche Bekämpfung der Orientalischen Schabe (Blatta orientalis) (L.) (Blattodea,Blattidae) and Hand eines Beispieles aus der Praxis

Zusammenfassung Die Orientalische Schabe (Blatta orientalis) wird in komplizierten Bekämpfungsterrains oft erfolglos bekämpft. Anhand eines Beispieles aus der Praxis werden Möglichkeiten aufgezeigt, wie man erfolgreich gegen die Orientalische Schabe vorgehen kann. Als entscheidender Gesichtspunkt wird die Aufspürung der Refugien angesehen. Die Orientalische Schabe zeigt eine hohe Affinität zu ihren Refugien. Die verschiedenen Bekämpfungsmethoden sollten sinnvoll kombiniert und aufeinander abgestimmt werden. Noch zu oft werden moderne Methoden der Schabenbekämpfung nicht angewendet und damit wichtige Einsatzmöglichkeiten vergeben. Die Ergebnisse der Arbeit vonFuchs, 1987) zum Verhalten vonBlatta orientalis sollten den Schädlingsbekämpfern auf Weiterbildungsveranstaltungen vermittelt werden.

---

Successful control of the Oriental cockroach (Blatta orientalis) (L.) (Blattodea, Blattidae) demonstrated by way of an example of real control

Attempts to control the Oriental cockroach (Blatta orienitalis) have often failed in complex territories. An example of real control is presented to demonstrate how the Oriental cockroach can be satisfactorily controlled. Tracking down the refuges of the pests is considered the decisive approach to control. The Oriental cockroach shows a close affinity for its refuges. The various methods of control should be usefully combined and coordinated. It has been found that modern methods of cockroach control are not adopted in a great many cases and, therefore, potential fields of application are not adequately used. The results of the work ofFuchs (1987) investigating the behaviour ofBlatta orientalis should be conveyed to pest control experts in training courses.

     

Evaluation of von Willebrand Factor During Pregnancy,Lactation and Oestrous Cycle in Bitches Affected and Unaffected by von Willebrand Disease

Plasmatic concentrations of von Willebrand Factor (vWF) increase during pregnancy in humans and dogs; however the mechanism of such increase is still not well defined. The aims of this study were: (i) to evaluate changes in vWF concentration during pregnancy and during the subsequent oestrous cycle in bitches affected and unaffected by von Willebrand Disease (vWD); (ii) to correlate the vWF levels and cortisol levels in both groups. Seven vWD affected (GI) and nine unaffected (GII) bitches were used. The animals were assessed during pregnancy, parturition, lactation and non‐gestational oestrous cycle in 11 moments (Pregnancy 1, Pregnancy 2, Parturition, Lactation 1, Lactation 2, Lactation 3, Anestrus, Proestrus, Oestrus, Diestrus 1, and Diestrus 2). The following tests were performed; measurement of von Willebrand factor antigen (vWF:Ag), albumin and cortisol. In both groups, vWF concentration remained stable during the non‐gestational oestrous cycle, but increased during pregnancy, with the highest value observed at parturition. Increases of 70% and 124% in vWF were seen in GI and GII, respectively, compared to anestrus. No correlation was found between vWF and cortisol. Values of vWF:Ag changed during pregnancy, with a peak at parturition, both in vWD affected and unaffected animals. Values of vWF were not altered in the different phases of the oestrous cycle following pregnancy in both groups. Evaluation of vWF during pregnancy can cause false negative results for vWD, but assessment can be performed at any point in the oestrous cycle of non‐pregnant bitches.     

Development and evaluation of a rapid absorbed enzyme immunoassay test for the diagnosis of Johne''s disease in cattle

An absorbed enzyme immunoassay (EIA) test for Johne's disease in cattle was developed in which absorption of cross-reacting antibodies occurred as a rapid reaction in solution rather than overnight with whole organisms and a subsequent centrifugation step. Total test time was reduced to less than 2 h with a minimum of manipulations. The test was evaluated in cattle herds from Johne's disease-endemic and Johne's disease-free regions of Australia. Specificity was 99.8%. Calculations of sensitivity were affected by the history of the herd under test. However, the EIA detected in excess of 80% of animals before onset of clinical disease and 65% of faecal shedders were EIA positive on, or before, first detection of Mycobacterium paratuberculosis in their faeces. The test should aid epidemiological studies and be a useful tool in the management and control of Johne's disease.     

Zur Lebensweise der Hausratte (Rattus rattus L.). Langjährige Beobachtungen in einer Getreidemühle bei Magdeburg

A large flour mill near Magdeburg was built in 1912 and has since been infested with house rats (Rattus rattus L.). Observations made over the past decades by personnel interested were acquired, and recorded together with own findings, in the course of which well-known facts of the habits of house rats were confirmed and thought-provoking shades added. Reference is made in this paper to varied issues including degree of infestation, skin colours, food, reproduction, as well as behavioural patterns and the problem area of control and extermination.