Live chilling of Atlantic salmon: physiological response to handling and temperature decrease on welfare

Investigation of the physiological effects of live chilling in Atlantic salmon, Salmo salar, has been performed in two experiments. In the first, fish (mean weight 840 g) acclimatized to either 16, 8, or 4°C were directly transferred horizontally or vertically (9 combinations) to water temperatures of 16, 8, 4, or 0°C using a dip net. Blood samples were collected at 1 and 6 h (h) post-transfer. In the second experiment, fish (mean weight 916 g) acclimatized to 16°C were exposed to four temperature-drop regimes (no physical handling): 16–4°C (over 5 h), 16–4°C (over 1 h), 16–0°C (over 5 h), and 16–0°C (over 1 h). Blood samples were collected 1 h post-temperature drop. Physical transfers in the first trial, i.e., temperature drops, resulted in immediate (1 h) increases in blood lactate concentrations at all three temperatures, but levels were significantly reduced and close to pre-transfer levels after 6 h. Horizontal transfers, i.e., 16–16°C, 8–8°C, and 4–4°C, resulted in similar increases and were not significantly different from the groups exposed to temperature drops. The most severe vertical transfer (16-0) resulted in a swift loss of equilibrium and eventually death. In experiment 2, temperature drops from 16 to 4°C and from 16 to 0°C over a period of one or 5 h, without physically handling the fish, resulted in no significant increases in any of the measured parameters 1 h post-transfer, except in the 16–0 (1 h) group. The latter experienced a significant increase in blood sodium, glucose, lactate, and cortisol levels compared to all other groups. The results suggest that salmon are capable of tolerating relatively steep temperature drops without any significant negative effects on blood stress parameters and that physical stress from handling overrides the effect of thermal insults.     

How Effective is Reduced Tillage–Cover Crop Management in Reducing N2O Fluxes from Arable Crop Soils?

Field management is expected to influence nitrous oxide (N₂O) production from arable cropping systems through effects on soil physics and biology. Measurements of N₂O flux were carried out on a weekly basis from April 2008 to August 2009 for a spring sown barley crop at Oak Park Research Centre, Carlow, Ireland. The soil was a free draining sandy loam typical of the majority of cereal growing land in Ireland. The aims of this study were to investigate the suitability of combining reduced tillage and a mustard cover crop (RT?CCC) to mitigate nitrous oxide emissions from arable soils and to validate the DeNitrification?CDeComposition (DNDC) model version (v. 9.2) for estimating N₂O emissions. In addition, the model was used to simulate N₂O emissions for two sets of future climate scenarios (period 2021?C2060). Field results showed that although the daily emissions were significantly higher for RT?CCC on two occasions (p?<?0.05), no significant effect (p?>?0.05) on the cumulative N₂O flux, compared with the CT treatment, was found. DNDC was validated using N₂O data collected from this study in combination with previously collected data and shown to be suitable for estimating N₂O emissions (r ²?=?0.70), water-filled pore space (WFPS) (r ²?=?0.58) and soil temperature (r ²?=?0.87) from this field. The relative deviations of the simulated to the measured N₂O values with the 140?kg N ha^?1 fertiliser application rate were ?36?% for RT?CCC and ?19?% for CT. Root mean square error values were 0.014 and 0.007?kg N₂O?CN ha^?1 day^?1, respectively, indicating a reasonable fit. Future cumulative N₂O fluxes and total denitrification were predicted to increase under the RT?CCC management for all future climate projections, whilst predictions were inconsistent under the CT. Our study suggests that the use of RT?CCC as an alternative farm management system for spring barley, if the sole objective is to reduce N₂O emissions, may not be successful.     

Technological Advances to Address Current Issues in Entomology: 2020 Student Debates

The 2020 Student Debates of the Entomological Society of America (ESA) were live-streamed during the Virtual Annual Meeting to debate current, prominent entomological issues of interest to members. The Student Debates Subcommittee of the National ESA Student Affairs Committee coordinated the student efforts throughout the year and hosted the live event. This year, four unbiased introductory speakers provided background for each debate topic while four multi-university teams were each assigned a debate topic under the theme ‘Technological Advances to Address Current Issues in Entomology’. The two debate topics selected were as follows: 1) What is the best taxonomic approach to identify and classify insects? and 2) What is the best current technology to address the locust swarms worldwide? Unbiased introduction speakers and debate teams began preparing approximately six months before the live event. During the live event, teams shared their critical thinking and practiced communication skills by defending their positions on either taxonomical identification and classification of insects or managing the damaging outbreaks of locusts in crops.     

治疗仔猪断奶后腹泻——复合产品是否值得一试

仔猪断奶后腹泻在猪场的发生率很高,这使养猪生产者遭受了严重的经济损失。有机酸可导致胃内pH值下降,不利于致病菌生存。但由于致病菌的固有抵抗力,含有大量游离有机酸的混合物,与植物化学物质和渗透性物质（Biotronic Top3）的联合使用可以更有效地提高动物的生产性能和控制致病菌。     

Zum Einfluß von Fumarsäure,Salzsäure,Natriumformiat, Tylosin und Toyocerin auf den Säure-Basen-Haushalt

Mit 6 Gruppen zu je 12 Ferkeln wurde ein Wachstumsversuch von 42 Tagen durchgeführt. In der fünften oder sechsten Versuchswoche wurde den Ferkeln durch Venenpunktion Blut für eine Blutgasanalyse entnommen. Bei Versuchsende erfolgte eine Blutentnahme zur Bestimmung des Kationen-, Anionen- und Harnstoffgehaltes im Blutplasma. Dem Futter wurde neben einer Kontrollration 1,8% Fumarsäure (Fms), 1,4% Salzsäure (HCl), 1,8% Natriumformiat (Nafo), 40 ppm Tylosin und 50 ppm Toyocerin (0,5 Mio. Keime/g) zugelegt und der Einfluß der Zulagen auf den Säure-Basen-Haushalt untersucht. Der Säure-Basen-Haushalt der Ferkel wurde durch die HCl-Behandlung in Form einer metabolischen Acidose gestört, die sich im venösen Blut durch einen gesichert erniedrigten pH-Wert sowie signifikant gesenkten Konzentrationen an Hydrogencarbonat und dem Basenüberschuß äußerte. Für die anderen Behandlungen war kein Einfluß auf den Säure-Basen-Haushalt nachzuweisen. Die Futter-Elektrolyt-Bilanz ergab für die HCl-Behandlung negative Werte. Die Konzentrationen an Natrium, Kalium, Calcium und Magnesium im Blutplasma waren durch die Zulagen nicht verändert. In der HCl-Behandlung war der Chloridgehalt am höchsten, der Phosphorgehalt um 10% erniedrigt. Die Behandlungen mit Nafo und HCl erbrachten signifikant geringere Harnstoffgehalte im Blutplasma als die Kontrolle.     

Lymphocyte blastogenesis and neutrophil function in cattle persistently infected with bovine viral diarrhea virus

Neutrophil function and mononuclear cell proliferative responses to mitogens were determined in healthy cattle and in cattle persistently infected with bovine viral diarrhea (BVD) virus. Uptake of [3H]thymidine by resting and mitogen-stimulated peripheral blood mononuclear cells was significantly lower in cattle persistently infected with BVD virus than in healthy cattle. Neutrophils from cattle persistently infected with BVD virus had significantly impaired capability to ingest Staphylococcus aureus, but were normal in respect to random migration under agarose, cytochrome C reduction, iodination, and antibody-dependent cell-mediated cytotoxicity. Impairment of neutrophil function in cattle persistently infected with BVD virus differs from impairment of neutrophil function reported in healthy cattle mounting an immune response to recent BVD virus infection.     

Use of laser Doppler flowmetry to determine blood flow in and viability of island axial pattern skin flaps in rabbits

Perfusion and viability of island axial pattern skin flaps were tested in 37 healthy New Zealand white rabbits, using laser Doppler monitoring of blood flow in the capillary loops and the subpapillary plexus of the dermis. Skin flaps, selected on the basis of the caudal superficial epigastric vein and artery, were lifted and replaced in their original locus after selective occlusion of their vascular pedicles. Subjects were allotted into groups: control group (n = 10); arterial occlusion (n = 7); venous occlusion (n = 10); and arterial and venous occlusion (n = 10). The rabbits were monitored from 48 hours before surgery until euthanasia 48 to 72 hours after replacement of the flap. Flap viability was assessed on a clinical basis, using a comparative scoring method based on a numeric scale. The degree of necrosis in histologic sections was evaluated, using a scoring system. Laser Doppler measurements were obtained on 3 consecutive days before surgery, to establish the normal basal blood flow in the skin. Postsurgical measurements were obtained at 2-hour intervals for the first 8 hours and at 24, 48, and 72 hours after surgery. Measurements of basal blood flow varied significantly (P less than 0.05) from site to site on the surface of individual flaps and over time. When laser Doppler flowmetric (LDF) measurements from 6 sites on a flap were used as a measure of laser Doppler flow for the total flap, there was no significant difference between contralateral flap areas outlined on the abdomen of the rabbits. Temporal variations over 3 days for each rabbit or among rabbits were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)