Chronic Copper Poisoning in Sheep: Structural Changes in Erythrocytes and Organs     

Nils E. Sli  Inger Nafstad 《Acta veterinaria Scandinavica》1976,17(3):316

Four cases of experimental copper poisoning in sheep were examined. Light microscopical and ultrastructural alterations of erythrocytes were observed a few hours before a significant haemolysis was evident. Heinz body formation in otherwise unchanged red cells was the first morphological alteration observed. The Heinz bodies were predominantly membrane-attached. During the haemolytic crisis severe erythrocytic distortion, structural membrane alteration and Heinz body-containing ghost cells were observed. Erythrophagocytosis was mainly located to the RE cells of the spleen. Intrafollicular necroses were found in all histological sections from the spleen. Pathological changes in liver and kidney were comparable to those of earlier reports, comprising hepatocellular and renal tubular necrosis.  相似文献   

Assessing the convergence of Markov Chain Monte Carlo methods: an example from evaluation of diagnostic tests in absence of a gold standard     

Toft N  Innocent GT  Gettinby G  Reid SW 《Preventive veterinary medicine》2007,79(2-4):244-256

The accessibility of Markov Chain Monte Carlo (MCMC) methods for statistical inference have improved with the advent of general purpose software. This enables researchers with limited statistical skills to perform Bayesian analysis. Using MCMC sampling to do statistical inference requires convergence of the MCMC chain to its stationary distribution. There is no certain way to prove convergence; it is only possible to ascertain when convergence definitely has not been achieved. These methods are rather subjective and not implemented as automatic safeguards in general MCMC software. This paper considers a pragmatic approach towards assessing the convergence of MCMC methods illustrated by a Bayesian analysis of the Hui–Walter model for evaluating diagnostic tests in the absence of a gold standard. The Hui–Walter model has two optimal solutions, a property which causes problems with convergence when the solutions are sufficiently close in the parameter space. Using simulated data we demonstrate tools to assess the convergence and mixing of MCMC chains using examples with and without convergence. Suggestions to remedy the situation when the MCMC sampler fails to converge are given. The epidemiological implications of the two solutions of the Hui–Walter model are discussed.  相似文献   

Aggression and cortisol levels in three different group housing routines for lactating sows     

Ola Thomsson  Ann-Sofi Bergqvist  Ylva Sjunnesson  Lena Eliasson-Selling  Nils Lundeheim  Ulf Magnusson 《Acta veterinaria Scandinavica》2015,57(1)

Background

Lactating sows in Swedish organic piglet production are commonly group-housed with piglets in a multi-suckling pen within 14 days after farrowing. Nursing behaviour may be disturbed when lactating sows are moved to a new environment and mixed with other sows, as they spend more time fighting with other sows and exploring the new surroundings. This can disrupt the inhibitory effect of suckling on ovarian activity and increase the risk of lactational oestrus, making efficient reproductive management difficult. Therefore this study evaluated aggression and levels of the stress hormone cortisol in lactating sows group-housed together with their piglets at one (W1), two (W2) or three (W3) weeks post farrowing.

Results

There was no significant difference (P > 0.05) between the three management routines (W1, W2, W3) regarding number of attacks initiated or received in the mixed group. After mixing, W2 sows had a lower number of shoulder scratches (P < 0.05) than W3 sows. Among the W3 sows, there was a lower (P < 0.01) cortisol concentration in saliva when sows were group housed compared to when they were individually housed. The cortisol response, measured as variation in cortisol concentration in saliva, was also lower (P < 0.05) in group-housed W3 sows compared with W1 sows.For all management routines, sows already living in the new environment (resident sows) initiated more attacks (P < 0.001) and received fewer attacks (P < 0.01) than sows entering the new environment (intruder sows). Overall, multiparous sows initiated more attacks and received fewer attacks than primiparous sows (P <0.001).

Conclusions

Overall, the results suggest that mixing and group housing sows at three weeks post farrowing is less stressful than mixing and group housing sows at one week post farrowing. The results also indicate that parity and whether a sow is a resident or intruder in the group housing environment may have an effect on aggression levels when sows are group-housed.  相似文献   

Weaner production with low antimicrobial usage: a descriptive study     

Mette Fertner  Anette Boklund  Nana Dupont  Claes En?e  Helle Stege  Nils Toft 《Acta veterinaria Scandinavica》2015,57(1)

Background

Health, productivity and antimicrobial use in the production of pigs are expected to be interrelated to some extent. Previous studies on register-based data have investigated these correlations with a subsequent large variation residing at the farm level. In order to study such farm factors in more detail we designed an elaborate interview-guide. By in-depth interviews of farmers with well-managed 7–30 kg (weaner) productions we sought to describe a set of common key-factors characterizing their management practices. Identification of such common practices could be used in follow-up projects, investigating whether identified factors really are characteristic for good-practicing famers.

Results

Eleven farms were selected for a farm visit and in-depth interview. Participating farms used less antimicrobials than the national median (8.2 animal daily doses/100 weaners/day), had a mortality below the national average (2.9%) and an average daily weight gain above the national average (443 g/day). Similarities were observed among participating farms, including the sectioning of farms, use of all-in-all-out procedures with subsequent cleaning, purchasing 7 kg weaners from only one source, as well as active participation in management by a committed farm owner. Most farmers had a specific point of focus in their management, and were convinced that this was the reason for their success. This included; feeding, treatment strategy, refurbishment of facilities and presence in the shed.

Conclusion

According to register data, participating farms were alike; in the good league regarding use of antimicrobials, mortality and daily growth. However, on-farm interviews elucidated more heterogeneity among farmers than expected. Most of the farmers had a specific point of focus, which they considered to be crucial for their good results. These results indicate the importance of non-registerable factors, highlighting the value of qualitative study techniques in the understanding of human actions. Further studies on the effect of various farmer types are recommended.  相似文献   

Assessment of the diversity of comfrey (Symphytum officinale L. and S. × uplandicum Nyman)     

Ruzicka  Joana  Berger-Büter  Karin  Esslinger  Nils  Novak  Johannes 《Genetic Resources and Crop Evolution》2021,68(7):2813-2825

Genetic Resources and Crop Evolution - Comfrey Symphytum officinale L. (true comfrey) and S.?×?uplandicum Nyman (a hybrid between S. asperum Lepech?×?S. officinale...  相似文献   

Heat flux anomalies in Antarctica revealed by satellite magnetic data   总被引：1，自引：0，他引：1  

Maule CF  Purucker ME  Olsen N  Mosegaard K 《Science (New York, N.Y.)》2005,309(5733):464-467

The geothermal heat flux is an important factor in the dynamics of ice sheets; it affects the occurrence of subglacial lakes, the onset of ice streams, and mass losses from the ice sheet base. Because direct heat flux measurements in ice-covered regions are difficult to obtain, we developed a method that uses satellite magnetic data to estimate the heat flux underneath the Antarctic ice sheet. We found that the heat flux underneath the ice sheet varies from 40 to 185 megawatts per square meter and that areas of high heat flux coincide with known current volcanism and some areas known to have ice streams.  相似文献   

Measuring specialization in species interaction networks     

Nico Blüthgen  Florian Menzel  Nils Blüthgen 《BMC ecology》2006,6(1):9-12

Background  

Network analyses of plant-animal interactions hold valuable biological information. They are often used to quantify the degree of specialization between partners, but usually based on qualitative indices such as 'connectance' or number of links. These measures ignore interaction frequencies or sampling intensity, and strongly depend on network size.  相似文献   

A critique of models for freshwater and soil acidification     

John O. Reuss  Nils Christophersen  Hans M. Seip 《Water, air, and soil pollution》1986,30(3-4):909-930

Four types of models quantifying effects of acid deposition on freshwaters are reviewed. These include Henriksen's empirical model, an adsorption isotherm model, soil-oriented charge balance models (Reuss-Johnson, Birkenes, MAGIC, ILWAS), and the Trickle Down model. Emphasis is on an assessment of critical assumptions; no attempt has been made to run the various models and compare results. The models range from simple to very complex and from empirical to highly process oriented. The various types have all proven useful and there has been a significant convergence concerning key processes. The importance of anion mobility, sulfate adsorption, ion exchange, dissolution of Al bearing minerals and weathering seems to be accepted by most workers. Future model improvement, however, relies to a large extent on further checking against observations.  相似文献   

Potential nitrogen and phosphorus leaching from soils fertilized with meat and bone meal     

Alhaji S. Jeng  Nils Vagstad 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):238-245

Abstract

The nitrogen and phosphorus contents of meat and bone meal (MBM) make it a potentially valuable nutrient source in agriculture. Its narrow N:P ratio, however, makes it a potential environmental risk if it is not utilized with caution. A column-leaching experiment was conducted to assess potential nitrogen and phosphorus leaching from bare soils fertilized with MBM. This should give an idea of the efficacy of autumn or early spring MBM application on land devoid of vegetation cover. Earlier greenhouse and field experiments have indicated that nitrogen mineralization after MBM application takes place relatively rapidly. The column experiment conducted here has indicated that spring application of MBM prior to planting can result in the loss of mineral nitrogen, reducing the total amount of N available to the crop. A higher initial loss (up to 47 mg l^?1) of ammonium was found for the MBM treated soils, but this declined to less than 0.1 mg l^?1 by the end of the experiment, 11 weeks later. Nitrate loss was highest at the onset of the experiment for the soils that received mineral N fertilizer. With time, however, the largest nitrate losses were associated with the MBM-treated soils. Nitrate leaching continued to well beyond the end of the experiment. The effect will most certainly be exacerbated when the crop N (rather than crop P) requirement forms the basis for MBM application. The amount of P leached as ortho-P is probably small but may also represent an environmental risk if N remains to be the basis of MBM application. Based on the results presented here and considering the dangers of elevated nutrient losses, autumn and early spring MBM application may not be recommended.  相似文献   

Effects of replacing fish meal with soy cake in a diet based on urea-treated rice straw on performance of growing Laisind beef cattle   总被引：1，自引：1，他引：0  

Duong Van Nhiem  Jan Berg  Nils Petter Kjos  Nguyen Xuan Trach  Bui Quang Tuan 《Tropical animal health and production》2013,45(4):901-909

The present study was to test if different ratios of fish meal to soy cake as protein supplements in the diet are not significantly different in effects on feed intakes and performance of growing beef cattle fed urea-treated rice straw (URTRS) as basal diet under local conditions in North Vietnam. Thirty-six male cattle of Laisind (50 % local Yellow cattle and 50 % Sindhi, both Bos indicus) at around 12 months of age with an average live weight of 124?±?12 kg at start were used in six groups of the experiment. Six diets named A, B, C, D, E, and F used in the experiment were similar in crude protein (CP) level, except for diet A with no supplementation, but different in fish meal/soy cake ratio based on CP content as follows: diet A 0/0, diet B 100/0, diet C 75/25, diet D 50/50, diet E 25/75, and diet F 0/100. Following a 4-week adaptation period, a comparison period lasted 24 weeks. The total intakes of dry matter (DM), DM from roughage, metabolizable energy (ME), and CP were 6, 7, 6, and 20 % higher in diets B–F than diet A with P values ≤0.05, 0.05, 0.05, and 0.001, respectively. The average daily gain (ADG) was 50 % higher (P?<?0.001) in diets B–F than that in diet A. Compared to diet A, diets B–F had lower feed conversion ratio (FCR)_DM, FCR_ME, and FCR_CP by 30, 20, and 30 %, respectively (all at P?<?0.001). There were no significant differences between diets B–F in the intakes, FCRs, and ADG. The apparent digestibility of CP was 12 to 24 % higher (P?<?0.001) in diets B–F than that in diet A. There was a tendency that the apparent digestibilities of DM, CP, and CF were increasing with increasing level of soy cake in this study. The ratio of fish meal to soy cake did not significantly affect feed intakes, ADG, FCR, and apparent nutrient digestibilities of the cattle. Soy cake can therefore be used to partially or fully replace fish meal as a protein supplement in the diet of growing beef cattle fed URTRS without any negative effects on animal performance.  相似文献