Anaerobic digestion of wastewater from hydrothermal liquefaction of sewage sludge and combined wheat straw-manure

Hydrothermal liquefaction (HTL) shows promise for converting wet biomass waste into biofuel, but the resulting high-strength process water (PW) requires treatment. This study explored enhancing energy recovery by anaerobic digestion using semi-batch reactors. Co-digesting manure with HTL-PW from wheat straw-manure co-HTL yielded methane (43-49% of the chemical oxygen demand, COD) at concentrations up to 17.8 gCOD·L-1, whereas HTL-PW from sewage sludge yielded methane (43% of the COD) up to only 12.8 gCOD·L-1 and complete inhibition occurred at 17 gCOD·L-1. Microbial community shifts confirmed inhibition of methanogenic archaea, while hydrolytic-fermentative bacteria were resilient. Differences in chemical composition, particularly higher levels of N-containing heterocyclic compounds in PW of sewage sludge, likely caused the microbial inhibition. The considerable potential of combining HTL with anaerobic digestion for enhanced energy recovery from straw-manure in an agricultural context is demonstrated, yet sewage sludge HTL-PW requires more advanced approaches to deal with methanogenesis inhibitors.

Energetically exploiting lignocellulose-rich residues in anaerobic digestion technologies: from bioreactors to proteogenomics

The biogas produced through anaerobic digestion (AD) of renewable feedstocks is one of the promising alternatives to replace fossil-derived energy. Even though lignocellulosic biomass is the most abundant biomass on earth, only a small fraction is being used towards resources recovery, leaving a great potential unexploited. In this study, the combination of state-of-art genomic techniques and engineered systems were used to further advance the knowledge on biogas production from lignocellulosic-rich residues and the microbiome involved in the anaerobic digestion hereof. A long-term adapted anaerobic microbiome capable of degrading wheat straw as the sole substrate was investigated using protein stable isotope probing (protein-SIP). The results indicated that a diverse microbial community, primarily composed of Firmicutes and Methanogens, played crucial roles in cellulose degradation and methane production. Notably, Defluviitoga tunisiensis, Syntrophothermus lipocalidus, and Pelobacter carbinolicus were identified as direct metabolizers of cellulose, while Dehalobacterium assimilated labelled carbon through cross-feeding. This study provides direct evidence of primary cellulose degraders and sheds light on their genomic composition. By harnessing the potential of lignocellulosic biomass and understanding the microbial communities involved, we can promote sustainable biogas production, contributing to energy security and environmental preservation.

Pig slurry organic matter transformation and methanogenesis at ambient storage temperatures

Manure management is a significant source of global methane emissions, and there is an increased interest in understanding and predicting emissions. The hydrolysis rate of manure organic matter is critical for understanding and predicting methane emissions. We estimated hydrolysis rate constants of crude protein, fibers, and lipids and used the Arrhenius equation to describe its dependency on temperature. Simultaneously, measurements of methane emission, 13/12 C isotope ratios, and methanogen community were conducted. This was achieved by incubating fresh pig manure without inoculum at 10°C, 15°C, 20°C, and 25°C for 85 days in a lab-scale setup. Hydrolysis of hemicellulose and cellulose increased more with temperature than crude protein, but still, hydrolysis rate of crude protein was highest at all temperatures. Results suggested that crude protein consisted of multiple substrate groups displaying large differences in degradability. Lipids and lignin were not hydrolyzed during incubations. Cumulative methane emissions were 7.13 ± 2.69, 24.6 ± 8.00, 66.7 ± 4.8, and 105.7 ± 7.14 gCH4 kgVS -1 at 10°C, 15°C, 20°C, and 25°C, respectively, and methanogenic community shifted from Methanosphaera toward Methanocorpusculum over time and more quickly at higher temperatures. This study provides important parameter estimates and dependencies on temperature, which is important in mechanistic methane emission models. Further work should focus on characterizing quickly degradable substrate pools in the manure organic matter as they might be the main carbon source of methane emission from manure management.

Assessing the potential of a membrane bioreactor and granular activated carbon process for wastewater reuse - A full-scale WWTP operated over one year in Scania, Sweden

A full-scale membrane bioreactor (MBR) with ultrafiltration, followed by granular activated carbon (GAC), was examined to determine the potential of reusing treated water as a source of drinking water or for irrigation. The major part of the bacteria removal took place in the MBR, whereas the GAC removed substantial amounts of organic micropollutants. Annual variations in inflow and infiltration resulted in a concentrated influent during summer and a diluted influent in the winter. The removal of E. coli was high throughout the process (average log removal 5.8), with effluent concentrations meeting the threshold for class B water standards for irrigation (EU 2020/741) but exceeding those for drinking water in Sweden. The total bacterial concentration increased over the GAC, indicating the growth and release of bacteria; however, E. coli concentrations declined. The effluent concentrations of metals met the Swedish criteria for drinking water. The removal of organic micropollutants decreased during the initial operation of the treatment plant, but after 1 year and 3 months, corresponding to 15,000 bed volumes, the removal increased. Maturation of the biofilm in the GAC filters might have resulted in biodegradation of certain organic micropollutants, in combination with bioregeneration. Although there is no legislation in Scandinavia with regard to many organic micropollutants in drinking water and water for irrigation, the effluent concentrations were generally in the same order of magnitude as to those in Swedish source waters that are used for drinking water production.

Effect of biofilm thickness on the activity and community composition of phosphorus accumulating bacteria in a moving bed biofilm reactor

Can biofilms enhance the rates of phosphorus removal in wastewater treatment? In order to narrow the scientific gap on the effect of biofilm thickness on the activity and microbial community of phosphorus-accumulating bacteria, this study investigated biofilms of 30 to 1000 µm thickness in a moving bed biofilm reactor. Measurements on 5 different biofilm carriers showed that biomass-specific phosphorus release and uptake rates increased as a function of biofilm thickness for biofilms thinner than about 110 µm but were lower for thicker biofilms of about 550-1000 µm. The reduced phosphorus uptake and release rates in the thickest biofilms can result from substrate mass transfer limitations whereas the low activity in the thinnest biofilms can be related to a too high turnover rate in the biofilm due to heterotrophic growth. Additionally, the microbial ecology of the different biofilms confirms the observed phosphorus uptake and release rates. The results from the full-length 16S rRNA gene sequencing of the bacterial community showed that the thicker biofilms were characterized by higher relative abundance (40-58%) of potential phosphorus accumulating genera Zoogloea, Acinetobacter, Dechloromonas and Ca. Accumulibacter. In contrast, the thinner biofilms were dominated by the genus Ferribacterium (34-60%), which might be competing with phosphorus-accumulating bacteria as indicated by the relatively high acetate uptake rates in the thinner biofilms. It is concluded that there is an optimal biofilm thickness of 100-500 µm, at which the phosphorus accumulating bacteria have the highest activity.

Proteomic Changes in Methicillin-Resistant Staphylococcus aureus Exposed to Cannabinoids

Methicillin-resistant Staphylococcus aureus (MRSA) is a major human pathogen that causes a wide range of infections. Its resistance to β-lactam antibiotics complicates treatment due to the limited number of antibiotics with activity against MRSA. To investigate development of alternative therapeutics, the mechanisms that mediate antibiotic resistance in MRSA need to be fully understood. In this study, MRSA cells were subjected to antibiotic stress from methicillin in combination with three cannabinoid compounds and analyzed using proteomics to assess the changes in physiology. Subjecting MRSA to nonlethal levels of methicillin resulted in an increased production of penicillin-binding protein 2 (PBP2). Exposure to cannabinoids showed antibiotic activity against MRSA, and differential proteomics revealed reduced levels of proteins involved in the energy production as well as PBP2 when used in combination with methicillin.

Assessing labelled carbon assimilation from poly butylene adipate-co-terephthalate (PBAT) monomers during thermophilic anaerobic digestion

PBAT (poly butylene adipate-co-terephthalate) is a widely used biodegradable plastic, but the knowledge about its metabolization in anaerobic environments is very limited. In this study, the anaerobic digester sludge from a municipal wastewater treatment plant was used as inoculum to investigate the biodegradability of PBAT monomers in thermophilic conditions. The research employs a combination of ¹³C-labelled monomers and proteogenomics to track the labelled carbon and identify the microorganisms involved. A total of 122 labelled peptides of interest were identified for adipic acid (AA) and 1,4-butanedio (BD). Through the time-dependent isotopic enrichment and isotopic profile distributions, Bacteroides, Ichthyobacterium, and Methanosarcina were proven to be directly involved in the metabolization of at least one monomer. This study provides a first insight into the identity and genomic potential of microorganisms responsible for biodegradability of PBAT monomers during anaerobic digestion under thermophilic conditions.

Proteomic characterisation of polyethylene terephthalate and monomer degradation by Ideonella sakaiensis

Synthetic plastics, like polyethylene terephthalate (PET), have become an essential part of modern life. Many of these products are remarkably persistent in the environment, and the accumulation in the environment is recognised as a major threat. Therefore, an increasing interest has been focusing on the screening for organisms able to degrade and assimilate the plastic. Ideonella sakaiensis originally isolated from a plastisphere has been reported as a bacterium that was solely thriving on the degradation on PET films. The processes affected by the presence of PET and its monomeric substances terephthalic acid, ethylene glycol, ethyl glycolate, and sodium glyoxylate monohydrate were elucidated by analysis of differential protein expression. The exposure of PET and its monomers induced the MHETase and affect two major pathways: the TCA cycle and the β-oxidation pathway. The increased expression of proteins directly or indirectly involved in these pathways suggests their underlying importance in the degradation of PET by I. sakaiensis since these proteins are mechanistically supporting the enzymes involved in the degradation of PET and its monomers.

Protein fractionation and shotgun proteomics analysis of enriched bacterial cultures shed new light on the enzymatically catalyzed degradation of acesulfame

The removal of organic micropollutants in municipal wastewater treatment is an extensively studied field of research, but the underlying enzymatic processes have only been elucidated to a small extent so far. In order to shed more light on the enzymatic degradation of the artificial sweetener acesulfame (ACE) in this context, we enriched two bacterial taxa which were not yet described to be involved in the degradation of ACE, an unknown Chelatococcus species and Ensifer adhaerens, by incubating activated sludge in chemically defined media containing ACE as sole carbon source. Cell-free lysates were extracted, spiked with ACE and analyzed via target LC-MS/MS, demonstrating for the first time enzymatically catalyzed ACE degradation outside of living cells. Fractionation of the lysate via two-dimensional fast protein liquid chromatography (FPLC) succeeded in a partial separation of the enzymes catalyzing the initial transformation reaction of ACE from those catalyzing the further transformation pathway. Thereby, an accumulation of the intermediate transformation product acetoacetamide-n-sulfonic acid (ANSA) in the ACE-degrading fractions was achieved, providing first quantitative evidence that the cleavage of the sulfuric ester moiety of ACE is the initial transformation step. The metaproteome of the enrichments was analyzed in the FPLC fractions and in the unfractionated lysate, using shotgun proteomics via UHPLC-HRMS/MS and label-free quantification. The comparison of protein abundances in the FPLC fractions to the corresponding ACE degradation rates revealed a metallo-β-lactamase fold metallo-hydrolase as most probable candidate for the enzyme catalyzing the initial transformation from ACE to ANSA. This enzyme was by far the most abundant of all detected proteins and amounted to a relative protein abundance of 91% in the most active fraction after the second fractionation step. Moreover, the analysis of the unfractionated lysate resulted in a list of further proteins possibly involved in the transformation of ACE, most striking a highly abundant amidase likely catalyzing the further transformation of ANSA, and an ABC transporter substrate-binding protein that may be involved in the uptake of ACE into the cell.

Microbial communities and metabolic pathways involved in reductive decolorization of an azo dye in a two-stage AD system

Multiple stage anaerobic system was found to be an effective strategy for reductive decolorization of azo dyes in the presence of sulfate. Bulk color removal (56-90%) was achieved concomitant with acidogenic activity in the 1st-stage reactor (R1), while organic matter removal (≤100%) and sulfate reduction (≤100%) occurred predominantly in the 2nd-stage reactor (R2). However, azo dye reduction mechanism and metabolic routes involved remain unclear. The involved microbial communities and conditions affecting the azo dye removal in a two-stage anaerobic digestion (AD) system were elucidated using amplicon sequencing (16S rRNA, fhs, dsrB and mcrA) and correlation analysis. Reductive decolorization was found to be co-metabolic and mainly associated with hydrogen-producing pathways. We also found evidence of the involvement of an azoreductase from Lactococcus lactis. Bacterial community in R1 was sensitive and shifted in the presence of the azo dye, while microorganisms in R2 were more protected. Higher diversity of syntrophic-acetate oxidizers, sulfate reducers and methanogens in R2 highlights the role of the 2nd-stage in organic matter and sulfate removals, and these communities might be involved in further transformations of the azo dye reduction products. The results improve our understanding on the role of different microbial communities in anaerobic treatment of azo dyes and can help in the design of better solutions for the treatment of textile effluents.

Proteogenomics identification of TBBPA degraders in anaerobic bioreactor

Tetrabromobisphenol A (TBBPA) is the most used flame retardant worldwide and has become a threat to aquatic ecosystems. Previous research into the degradation of this micropollutant in anaerobic bioreactors has suggested several identities of putative TBBPA degraders. However, the organisms actively degrading TBBPA under in situ conditions have so far not been identified. Protein-stable isotope probing (protein-SIP) has become a cutting-edge technique in microbial ecology for enabling the link between identity and function under in situ conditions. Therefore, it was hypothesized that combining protein-based stable isotope probing with metagenomics could be used to identify and provide genomic insight into the TBBPA-degrading organisms. The identified ¹³C-labelled peptides were found to belong to organisms affiliated to Phytobacter, Clostridium, Sporolactobacillus, and Klebsilla genera. The functional classification of identified labelled peptides revealed that TBBPA is not only transformed by cometabolic reactions, but also assimilated into the biomass. By application of the proteogenomics with labelled micropollutants (protein-SIP) and metagenome-assembled genomes, it was possible to extend the current perspective of the diversity of TBBPA degraders in wastewater and predict putative TBBPA degradation pathways. The study provides a link to the active TBBPA degraders and which organisms to favor for optimized biodegradation.

Unravelling gradient layers of microbial communities, proteins, and chemical structure in aerobic granules

Most bacteria live in microbial assemblages like biofilms and granules, and each layer of these assemblages provides a niche for certain bacteria with specific metabolic functions. In this study, a gentle (non-destructive) extraction approach based on a cation exchange resin and defined shear was employed to gradually disintegrate biomass and collect single layers of aerobic granules from a full-scale municipal wastewater treatment plant. The microbial community composition of granule layers was characterized using next-generation sequencing (NGS) targeting the 16S rRNA gene, and protein composition was investigated using metaproteomics. The chemical composition of eroded layers was explored using Fourier Transformed Infrared Spectroscopy. On the surface of the granules, the microbial structure (flocculation-supporting Nannocystis sp.) as well as composition of extracellular polymers (extracellular DNA) and proteome (chaperonins and binding proteins) favored microbial aggregation. Extracellular polymeric substances in the granules were composed of mostly proteins and EPS-producers, such as Tetrasphaera sp. and Zoogloea sp., were evenly distributed throughout the granule structure. The interior of the granules harbored several denitrifiers (e.g., Thauera sp.), phosphate-accumulating denitrifiers (Candidatus Accumulibacter, Dechloromonas sp.) and nitrifiers (Candidatus Nitrotoga). Proteins associated with glycolytic activity were identified in the outer and middle granule layers, and proteins associated with phosphorus conversions, in the deeper layers. In conclusion, the use of an existing cation-exchange resin for gradual biomass disintegration, combined with NGS and metaproteomic analysis was demonstrated as a promising approach for simultaneously investigating the identity and functions of microbes in multilayered biofilm structures.

Characterisation of cellulose-degrading organisms in an anaerobic digester

The recalcitrant nature of lignocellulosic biomass hinders efficient exploitation of this fraction for energy production. A better understanding of the microorganisms able to convert plant-based feedstocks is needed to improve anaerobic digestion of lignocellulosic biomass. In this study, active thermophilic cellulose-degrading microorganisms were identified from a full-scale anaerobic digester fed with maize by using metagenome-resolved protein stable isotope probing (protein-SIP). ¹³C-cellulose was converted into ¹³C-methane with a ^13/12C isotope ratio of 0.127 after two days of incubation. Metagenomic analysis revealed 238 different genes coding for carbohydrate-active enzymes (CAZymes), six of which were directly associated with cellulose degradation. The protein-SIP analysis identified twenty heavily labelled peptides deriving from microorganisms actively assimilating labelled carbon from the degradation of ¹³C-cellulose, highlighting several members of the order Clostridiales. Corynebacterium was identified through CAZyme screening, amplicon analysis, and in the metagenome giving a strong identification of being a cellulose degrader.

Tetrabromobisphenol A (TBBPA) biodegradation in acidogenic systems: One step further on where and who

The occurrence of brominated flame retardants such as Tetrabromobisphenol A (TBBPA) in water bodies poses a serious threat to aquatic ecosystems. Degradation of TBBPA in wastewater has successfully been demonstrated to occur through anaerobic digestion (AD), although the involved microorganisms and the conditions favouring the conversion remains unclear. In this study, it was observed that bioconversion of TBBPA did not occur during the hydrolytic stage of the AD, but during the strictly fermentative stage. Bioconversion occurred in hydrolytic-acidogenic as well as in strictly acidogenic continuous bioreactors. This indicates that the microorganisms that degrade TBBPA benefit from the electron flux taking place during glycolysis and further transformations into short-chain fatty acids. The degradation kinetics of TBBPA was inversely proportional to the complexity of the wastewater as the apparent kinetics constants were 2.11, 1.86, and 0.52 h^-1·gVSS^-1 for glucose, starch, and domestic sewage as carbon source, respectively. Additionally, the micropollutant loading rate relative to the overall organic loading rate is of major importance during the investigation of cometabolic transformations. The long-term exposure to TBBPA at environmentally realistic concentrations did not cause any major changes in the microbiome composition. Multivariate statistical analysis of the evolvement of the microbiome throughout the incubation suggested that Enterobacter spp. and Clostridium spp. are the key players in TBBPA degradation. Finally, a batch enrichment was conducted, which showed that concentrations of 0.5 mg·L^-1 or higher are detrimental to Clostridium spp., even though these organisms are putative TBBPA degraders. The Clostridium genus was outcompeted by the Enterobacter and Klebsiella genera, hereby highlighting the effect of unrealistic concentrations frequently used in culture-dependent studies on the microbial community composition.

Wood-Ljungdahl pathway utilisation during in situ H2 biomethanation

Biogas production from organic waste is a waste-to-energy technology with the potential to contribute significantly to sustainable energy production. Upgrading of biogas using in situ biomethanation with hydrogen has the potential for surplus electricity storage, and delivery of biogas with a methane content of >90%, allowing for easier integration into the natural gas grid, as well as conversion to other products. Microbial communities in biomethanation reactors undergo changes, however, these changes are largely unexplored. In the present study, metagenome-resolved protein stable isotope probing (Protein-SIP) was applied to laboratory scale batch incubations operating under anaerobic digestion, and (pre-adapted) biomethanation conditions, fed with ¹³C-labelled bicarbonate, in order to gain insight into the microbial activities during CO₂-reduction. The strongest and most microbially diverse isotopic incorporation was observed in the pre-adapted biomethanation incubation. Furthermore, divergent incorporation of ¹³C-labelled bicarbonate was also observed in the Wood-Ljungdahl pathway, with the anaerobic digester incubations primarily showing labelled proteins in the peripheral pathways leading toward production of energy and biomass. The pre-adapted biomethanation incubations consumed H₂ and CO₂, but did not convert it to CH₄, suggesting the production of acetate in these incubations, which was supported by heavy labelling of key enzymes in the Wood-Ljungdahl pathway. Twelve (ten high quality) metagenome-assembled genomes (MAGs) coding for ¹³C-incorporated proteins were extracted from the metagenome, eight of which contained one or more of the key genes in the Wood-Ljungdahl pathway, one of which was affiliated to Methanosarcina. Together, the findings in the present study deepen our knowledge surrounding microbial communities in biomethanation systems, and contribute to the development of better strategies for implementation of biogas upgrading and microbial management.

Pathogenicity of selected Toxoplasma gondii isolates in young pigs

The pathogenicity in 7-week-old pigs to five different Toxoplasma gondii strains of various host species origin was compared after i.v. inoculation of 10(4) tachyzoites. Additionally, one group of pigs was inoculated i.v. with 10(6) tachyzoites of the reference strain, SSI 119. In response to the infection a significant effect of T. gondii tachyzoite inoculation dose as well as differences among strains could be observed in several parameters. The 10(6)-dose inoculated pigs showed variable degrees of clinical illness and recurrent episodes of fever 4-17 days p.i., while pigs of four of the 10(4) tachyzoite inoculated groups experienced a short-lived rise in body temperature from day 6-8 p.i. without any apparent illness or inappetence. Control pigs and pigs infected with the least pathogenic strain had normal body temperature throughout the experiment. In all inoculated pigs, T. gondii-specific IgM and IgG antibodies appeared from day 8-10 and 10-17 p.i., respectively. Serum levels of alkaline phosphatase and the acute phase protein haptoglobin were decreased or increased, respectively, in response to the infection. Differential leukocyte count on peripheral blood revealed a significant lymphocytopenia on day 6 p.i. equal to both CD4+ and CD8+ T-cells, but shifting towards a reduced ratio of CD4+/CD8+ T-cells from day 8-14 p.i. In the 10(6)-dose inoculated pigs a considerable increase in zymosan induced and spontaneous oxidative burst capacity of peripheral blood leukocytes was observed from 6 days p.i. compared with control pigs. Oxidative burst capacity was not examined for other pigs. In conclusion, several useful parameters to identify differences in T. gondii pathogenicity other than mortality were identified. Furthermore, even at low doses, significant differences between recently collected Danish T. gondii field isolates were demonstrated after i.v. inoculation in young pigs.

Comparison of results of haematological and clinical chemical analyses of blood samples obtained from the cephalic and external jugular veins in dogs

The study was performed to investigate the difference in the concentration of several haematological and clinical chemical blood components in blood obtained from the cephalic and external jugular veins in 23 dogs. A total of 17 laboratory tests were analysed and, except for two clinical chemical blood components, there was no decisive difference in the test results obtained in blood samples collected from the cephalic and external jugular vein in dogs. For creatinine and potassium, however, there was a significant difference in the test results between the two veins, the highest results in general being measured in jugular venous blood. These findings indicate that it may be advisable to establish standardised procedures when collecting blood samples and make adjustments for the difference in test results when interpreting them.

Adaptation of a commercially available enzyme linked immunosorbent assay (ELISA) for the determination of thyroxine in canine plasma samples

The purpose of the present study was to modify a previously evaluated enzyme linked immunosorbent assay (Larsson and Lumsden, 1980) for the determination of the thyroxine (T4) concentration in canine plasma samples. The test kit Enzymun-Test(Boehringer Mannheim) for determination of T4 concentrations in human plasma was used in connection with the analyzer system Enzymun-Test(Boehringer Mannheim) System ES-33. The assay protocol originally used by Larsson and Lumsden (1980) was modified by including an additional standard, prolongation of the incubation period for the immunoreaction and the enzymeassay, and reduction of the amount of T4 conjugate. The intra- and interassay coefficient of variations ranged from 3.8% to 12.5%. The detection limit of the assay was 3.9 nmol/l which is well below the T4 concentration observed in plasma from healthy dogs, and the T4 concentrations determined in plasma from healthy dogs before and 3 hours after administration of TRH (38.0 +/- 7.4 nmol/l and 51.8 +/- 8.5 nmol/l, respectively) were comparable to those reported in the literature.

Evaluation of diagnostic tests using relative operating characteristic (ROC) curves and the differential positive rate. An example using the total serum bile acid concentration and the alanine aminotransferase activity in the diagnosis of canine hepatobiliary diseases

The value of a diagnostic test depends on most cases on its ability to discriminate between patients with and without a certain disease. One way of evaluating a diagnostic test is to use the relative operating characteristic curve (ROC curve) and the differential positive rate (DPR). The ROC curve displays the relationship between the true positive ratio and the false positive ratio for a range of cutoff values and it can be used to compare various diagnostic tests under equivalent conditions (equal true positive ratios or false positive ratios) and over the entire range of cutoff values. The DPR is the difference between the true positive ratio and the false positive ratio at various cutoff values and it can be used to obtain the cutoff value associated with the highest sensitivity and specificity. The purpose of this study was to describe the evaluation and comparison of diagnostic tests using ROC curves and DPR. Eventually, the positive and negative predictive values were used to assess the differences between the sensitivity and specificity obtained when the upper limit of the reference interval, or the optimal cutoff value indicated by the DPR, was used as cutoff value. To illustrate the methods, the 2 h post-prandial total serum bile acid concentration (PSBA) and the alanine aminotransferase activity (ALAT) in the diagnosis of primary or secondary hepatobiliary diseases in dogs were used. The ROC curves showed, as expected from previous studies, that PSBA was superior to ALAT in diagnosing dogs with hepatobiliary diseases. Using DPR, the optimal cutoff value for PSBA was suggested to be 15.48 mumol/l. Compared to the traditionally used cutoff value of 22.24 mumol/l, no decisive difference in the positive predictive values were observed. However, the cutoff value of 15.48 mumol/l appeared to produce higher negative predictive values compared to a cutoff value of 22.24 mumol/l. Seemingly, ROC curves and DPR are simple methods useful to the evaluation of diagnostic tests and due to the simplicity, there seems to be a great potential for these methods in the evaluation of diagnostic tests in veterinary medicine.

Preliminary experience with the diagnostic value of the canine corticosteroid-induced alkaline phosphatase isoenzyme in hypercorticism and diabetes mellitus

The present study communicates the interim experience with the diagnostic value of the canine corticosteroid-induced alkaline phosphatase isoenzyme (CIAP), qualitatively assessed by agarose gel electrophoresis, for the diagnosis of Hypercorticism (prolonged exposure to increased concentrations of exogenous or endogenous corticosteroids) and Diabetes mellitus. A total of 106 canine serum samples with a total alkaline phosphatase activity greater than 2.90 mu kat/l were included. CIAP was identified in 28 out of 29 cases of Hypercorticism, in 7 out of 9 cases of Diabetes mellitus, and in 33 out of 68 cases of various other diseases. Sensitivity and specificity with respect to Hypercorticism were 0.97 and 0.48, respectively, while for Diabetes mellitus sensitivity and specificity were 0.78 and 0.37. From this, the positive and the negative predictive values were calculated using standard formulas. The main conclusion may be summarized as follows: In the dog, only the negative finding of CIAP seems to be of diagnostic value in ruling out Hypercorticism as a cause for an increased total alkaline phosphatase activity.

The comparative haematology of cross-bred and indigenous east African goats of Tanzania and breeds reared in Denmark

Erythrocyte counts, haematocrit, haemoglobin concentration, red blood cell indices, total and differential leukocyte counts were determined in 202 cross-bred and 14 indigenous East African goats aged 6-12 months and also in 59 Norwegian dairy goats, of which 24 were 15-45 days old, 8 were 8 months old and 27 were over 3 years and pregnant. These were reared in Tanzania. Comparisons were made with 24 Dwarf and 57 Danish Landrace goats at 6-12 months of age and 76 adult pregnant Danish Landrace goats reared in Denmark. The purpose was to determine reference ranges for cross-bred and indigenous East African goats and to compare these with those of other breeds. The haemoglobin concentration, haematocrit, erythrocyte and white blood cells were lowest in the Norwegian kids. The highest values were observed in 6-12-month-old goats in all the breeds, whereafter they decreased to relatively constant adult levels. The mean corpuscular volumes were highest in kids followed by adult pregnant Norwegian and Danish Landrace goats, and lowest in 6-12 months old goats. East African and cross-bred goats had the smallest mean corpuscular volumes. The haemoglobin concentration, erythrocyte and leukocyte counts were highest in indigenous East African, followed by young Norwegian and cross-bred goats. The mean corpuscular haemoglobin concentration was highest in the cross-breds, while the mean corpuscular haemoglobin was higher in pregnant than in other goats. The age and breed differences were statistically significant.

Profiles of some clinical chemical parameters in growing dwarf and landrace kids

Plasma creatinine, urea, bilirubin, glucose, cholesterol, calcium, magnesium, sodium, potassium, inorganic phosphorus and total serum proteins were analyzed in kids of Dwarf and Danish Landrace breeds from birth to 12 months of age. The purpose was to determine the reference ranges, age profiles and the influence of other factors. Comparisons between parametric (mean +/- standard deviation) and the corresponding nonparametric (5th and 95th percentile, median) values were calculated for each parameter, the results of which indicated no apparent differences. The levels were very much dependent on age. Creatinine, urea and total serum protein levels increased gradually with age. Glucose and cholesterol levels were high at birth and then decreased with age. The electrolyte concentrations were maintained within narrow limits. Significant differences were observed between kids of different ages (within the breeds), breeds (within similar age) and herds (within the same age and breed). Differences between female and male Landrace kids of the same ages were observed in plasma urea, creatinine, glucose and total serum proteins. It is concluded that age has a major influence on the clinical chemical reference values in young goats, followed by herd and breed, but the influence of sex was small and is negligible in most parameters.

Profile of some plasma enzyme activities in growing dwarf and landrace kids

Plasma alanine aminotransferase, aspartate aminotransferase, creatine kinase and alkaline phosphatase activities were studied in clinically healthy Danish landrace and dwarf kids in seven herds from birth to 12 months of age. The purpose was to evaluate the influence of age, breed and herd on reference values. The mean enzyme levels +/- standard deviation (s) in neonatal dwarf kids were 0.09 +/- 0.04, 1.23 +/- 0.24, 2.79 +/- 1.50 and 18.3 +/- 11.0 mu kat/l respectively. The respective values in landrace kids were 0.13 +/- 0.06, 1.06 +/- 0.22, 2.44 +/- 1.60 and 37.6 +/- 23.6 mu kat/l. In 8-12 months old dwarf kids they were 0.30 +/- 0.11, 1.49 +/- 0.13, 3.28 +/- 0.44 and 11.1 +/- 2.4 mu kat/l respectively and 0.23 +/- 0.05, 1.12 +/- 0.34, 3.68 +/- 1.63 and 14.1 +/- 8.40 mu kat/l respectively in landrace kids of the same age. The 5th to 95th percentile intervals of the enzyme activities were within mean +/- 2s for most age groups in both breeds except alkaline phosphatase. The means and medians were close to each other for the values of alanine aminotransferase, aspartate aminotransferase and creatine kinase but not for alkaline phosphatase. Alanine aminotransferase, aspartate aminotransferase and creatine kinase levels were low at birth and increased with age, whereas for alkaline phosphatase it was vice versa. Significant differences were observed in mean enzyme activities between kids of different ages (within breeds), breeds (in same age kids) and herds (within same breed and age kids). Sex variations (within the breeds) were not observed. It was concluded that plasma enzyme activities are dependent on age, breed and environment.

Haematological profile in neonatal dwarf and landrace kids

The haematological profile in neonatal dwarf and Danish landrace kids was investigated in 62 healthy Danish landrace and 34 dwarf kids from birth to 12 months of age in 7 herds. The objective was to determine the reference values in the breeds, and evaluate the influence of age and environment on haematological parameters. Parametric (means and standard deviations) and non-parametric (5th, 95th percentile, median) values were calculated for each analysis. Results of the two statistical methods were close to each other. The number of erythrocytes in both breeds increased with age from neonatal minimum values. Haemoglobin concentration and haematocrit decreased from the neonatal values in the following two weeks of life, whereafter they increased. Haemoglobin concentration and mean corpuscular volumes were significantly higher in neonatal dwarf than in landrace kids. Differences in erythrocyte counts and haematocrit were observed with subsequent growth. There were significant differences in erythrocyte counts, haemoglobin concentration, haematocrit, mean corpuscular volume and mean corpuscular haemoglobin, between breeds (in kids of similar age), age groups (within the breeds) and herds (in kids of similar age within the breeds). Statistically significant differences in haematological values between female and male kids of similar young ages within the same breed were not observed. Age, breed and environment influenced the level of haematological parameters in kids.

Comparison between a modified haemocytometric technique and electronic counters in goat blood cell counting

Dilutions of goat blood with Hayem-Jørgensen's fluid ranging from 1:200 to 1:1,000 were used for haemocytometer counting of red blood cells (RBC) in 27 goats. The optimal dilutions were 1:400-1:500. Correlation studies between the results obtained by the haemocytometer and the Coulter counter red blood cell (RBC) and white blood cell (WBC) counts were performed in 551 goat blood samples. The haemocytometer RBC counts were 5.63% higher and WBC counts 2.79% lower than those of the electronic counter. The method of blood cell counting therefore influences the clinical haematological diagnoses and reference values in domestic animals. New cell counters specifically designed to measure cells of small volumes, e.g. goat erythrocytes, are needed.

Leukocyte profile in growing dwarf and landrace kids

Total and differential leukocyte count profiles were studied in 62 clinically healthy Danish landrace kids and 34 clinically healthy dwarf kids from birth to 12 months of age in seven Danish herds. The objective was to determine the reference values in the two breeds and the influence of age, sex and environment and whether there are any breed differences. Parametric (mean +/- 2 standard deviations) and the nonparametric (5th to 95th percentile interval) values for each leukocyte type were closely related. The medians were very close to the means. The number of leukocytes was low in neonates, 7.1 +/- 1.5 and 7.0 +/- 2.1 x 10(9)/l in dwarf and landrace kids respectively. Values increased with age to 18.7 +/- 2.1 and 13.4 +/- 3.1 x 10(9)/l in the two breeds respectively at 8-12 months of age. There were significant differences in leukocyte counts between the breeds at 1-2 and 8-12 months of age and at 2-4 months between herds within the breeds. The number of lymphocyte and neutrophil cells were 2.6 +/- 0.8 and 3.9 +/- 1.1 x 10(9)/l respectively in neonatal dwarf and 4.1 +/- 1.5 and 2.3 +/- 1.1 x 10(9)/l respectively in landrace kids. Very high numbers of these cells were observed in dwarf and landrace kids respectively within 8 months, 10.7 +/- 1.1 and 8.2 +/- 3.3 lymphocytes and 6.8 +/- 1.7 and 4.4 +/- 2.6 x 10(9)/l neutrophils for the two breeds. Significant differences between the ages (within the breeds), breeds (within similar ages) and herds (within breeds in kids of similar ages) were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Erythrocyte maturation in neonatal dwarf and landrace kids

The morphology of the erythrocyte cell series was investigated in external jugular vein blood samples from Dwarf and Danish Landrace goats aged from one day to 12 months. Three erythrocytic cell types were observed in neonates after supravital staining with new methylene blue. The first type were macrocytes which were stained uniformly dark to muddy blue. They formed the majority of the erythrocytic cells at birth and were categorized as diffusely basophilic chromatophilic erythrocytes. The second type were punctate and aggregated reticulocytes, and the third type were mature erythrocytes. The size ranges of the three erythrocytic cells were 4.2-5.6, 4.9-6.3 and 2.8-3.5 microns diameter respectively in the Dwarf kids and 5.6-9.7, 4.2-9.0 and 3.8-4.2 microns respectively in the Landrace kids during the first week of life. Romanowsky-stained blood smears from neonatal kids were characterized by anisocytosis and poikilocytosis in which polychromatophilic macrocytes were numerous, but reticulocytes were not clearly identifiable. The ranges of erythrocyte diameters in Romanowsky-stained neonatal blood films were 4.4-5.8 (5.2 +/- 0.39) and 4.1-6.7 (5.1 +/- 0.67) microns in Dwarf and Landrace kids respectively, decreasing to 3.0 +/- 0.15 and 3.3 +/- 0.13 microns in the two broods respectively by 12 months of age. The numbers of diffusely basophilic polychromatophilic erythrocytes and punctate/aggregated reticulocytes diminished with age and they were not observed in 1-2-month-old kids.

Influence of pregnancy, lactation and environment on some clinical chemical reference values in Danish landrace dairy goats (Capra hircus) of different parity--I. Electrolytes and enzymes

1. Plasma calcium, magnesium, inorganic phosphorus, sodium and potassium concentrations, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and creatine kinase activities were determined in young and adult non-pregnant non-lactating, early and late non-lactating pregnant and early, mid- and late non-pregnant lactating Danish landrace goats in five herds. The purpose was to determine the influence of pregnancy and lactation on the levels of these parameters and the effect of age and parity on the changes. 2. Calcium, phosphorus, alanine aminotransferase, alkaline phosphatase and aspartate aminotransferase decreased in late gestation. Magnesium and creatine kinase decreased in early lactating goats but increased in subsequent lactation periods. Sodium and potassium fluctuated little during pregnancy and lactation. Calcium, magnesium and potassium profiles were inversely, while phosphorus was directly, proportional to parity. 3. There were significant differences in most ions and enzymes between goats of different herds (within the same physiological state). 4. The transferases and creatine kinase were higher in young goats than in old ones, while alkaline phosphatase was unpredictably high or low in individual goats. 5. Alterations in the level of plasma electrolytes and enzyme activities occur due to pregnancy and lactation and the degree depends on age and parity, influenced also by environment.

Influence of pregnancy, lactation and environment on haematological profiles in Danish landrace dairy goats (Capra hircus) of different parity

1. Haematological analysis was performed in young and adult non-pregnant, non-lactating, early and late pregnant, early mid- and late lactating Danish landrace goats from five herds. The purpose was to determine whether their levels are significantly different in these states and the effect of age and parity on the changes. 2. The haematocrit, haemoglobin concentration, number of erythrocytes and leukocytes were higher in 8-12 month old non-pregnant and 1-2 year old pregnant goats than in adult pregnant and lactating goats of over 2 years of age. Haematocrit, haemoglobin concentration and the number of erythrocytes decreased in late pregnancy and early lactation. 3. At the same time mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration slightly increased. 4. The changes were directly proportional to parity, more in pluriparous than in primiparous goats. 5. After parturition the former group of parameters increased and the latter decreased. 6. There was an increase in the number of total leukocytes close to and after parturition due to neutrophils and lymphocytes and it was more pronounced in the first lactation than in pluriparous goats. 7. There were significant differences in many parameters between goats from different herds (within similar physiological states).

Influence of pregnancy, lactation and environment on some clinical chemical reference values in Danish landrace dairy goats (Capra hircus) of different parity--II. Plasma urea, creatinine, bilirubin, cholesterol, glucose and total serum proteins

1. Plasma urea, creatinine, bilirubin, glucose, cholesterol and total serum proteins were determined in Danish landrace goats from five herds in early and late gestation, during lactation and in dry goats. The purpose was to determine if there are sustained alterations in the levels of these parameters due to pregnancy and lactation and whether the changes are dependent on age, parity and environment. 2. Urea, creatinine and bilirubin were higher in young non-pregnant goats than in others. Urea decreased in goats at early and mid-lactation directly proportional to parity so that the higher the parity the more the decrease. 3. Creatinine was higher in young and adult non-pregnant goats than in others. There was an increase in late lactation that was greater in goats of higher parity than in others. 4. Bilirubin was higher in the mid-lactation stage, much more in goats of higher parity than in others. 5. Glucose concentration was lower in pregnant than in lactating goats and increased during lactation. The decrease during pregnancy was greater in higher parity goats than in others. 6. Plasma cholesterol and total serum proteins increased during lactation directly proportional to parity. 7. There were significant differences in biochemical parameters between goats from different herds (within similar physiological states). 8. Sustained alterations of these biochemical parameters occur during pregnancy and lactation in goats; the magnitude of changes depends on age and parity, and varies between herds.

Technical evaluation of a naso-ruminal instrument for collection of ruminal samples in non-fistulated cows

The sampling method used is of great importance for the estimation of the microbial activity and biochemical status in ruminal fluid (Stöber & Tiefenbach 1958, Keindorf 1974, Behravesh 1984). Several methods have been used for sampling of ruminal fluid in non-fistulated animals (Sørensen & Schambye 1955, Perk 1958, Schultz & Hiepe 1958, Keindorf & Link 1971). However, the conventional methods of collecting ruminal fluid either by stomach tube (Thygesen probe with a filter ad modum Sørensen & Schambye (1955)), or through a puncture low in the left flank, do not produce representative samples comparable in quality or quantity to samples collected directly through a rumen fistula. The puncture methods usually produce a very small volume of material, and they often leave the cow with an inflammatory reaction in the flank. Many research workers have demonstrated contamination with saliva in samples drawn through a peroral stomach tube, resulting inter alia in a higher pH value than in samples collected through fistula (Dirksen 1970, Behravesh 1984). Since changes in the fermentative reactions of high-yielding cows are receiving much research emphasis today, it has been our aim to construct an instrument suitable for collecting single or continuous samples for diagnostic as well as research purposes, which are comparable in quality and quantity to samples obtained through a rumen fistula. The idea of making the naso-ruminal sampler was inspired by the construction of the COMET Naso-Reticular Instrument (Hekmati et al. 1985).

Clinical chemical comparative examination of ruminal samples collected by means of a naso-ruminal sampler

Samples of ruminal fluid collected with the COMET naso-ruminal sampler and by two other methods through fistula were subjected to comparative clinical chemical examination. It was found that the mean values of pH and buffer capacity were nearly identical for all three methods. The greatest variation between the methods were found for reduction time of methylene blue owing to different dry matter contents in the samples. The VFA contents were nearly identical in all three samples.

In conclusion, it was found that it is possible to obtain ruminal samples that are representative of the biochemical status in the rumen by means of the COMET naso-ruminal sampler in non-fistulated cows.

Changes in ionized calcium content and related clinical chemical parameters in cases of left-sided abomasal displacement

There is still uncertainty about the etiology and pathogenesis of abomasal displacement. Changes in total and ionized calcium are considered to be important pieces in the mosaic of causative factors. The present study on pre- and postoperative clinical chemical changes revealed a preoperative reduction in ionized calcium values. The reduction seemed mainly to be due to changes in the pH of blood.

Examination of mink (Mustela vison) fed a sulphuric acid preserved fish silage during lactation and growth period. II. Production and pathologic studies correlated to results of clinical-chemical studies

Earlier and present experiments have shown detrimental influence of sulphuric acid preserved fish in mink feed on production parameters, early kit growth and kit mortality. Comparison of the production parameters with clinical-chemical parametres and pathological-anatomical findings give a picture of the tolerated amount of sulphuric acid preserved fish silage in the mink feed during different production periods. It seems that the animals tolerate only small amounts of sulphuric acid preserved fish silage (5-8 per cent) in the total feed during the stress periods of reproduction, lactation and early kit growth but higher amounts (20-30 per cent) during late growth period, where the need of feed is high.

Examination of mink (Mustela vison) fed a sulphuric acid preserved fish during lactation and growth period. I. A clinical-chemical examination

Addition of sulphuric acid preserved fish in great amounts as fur animal feed has a serious influence on the metabolism of the animals. The present experimental work shows that several clinical-chemical parameters are changed during feeding of acid preserved feed resulting in changes of the fluid-, electrolyte- and acid-base balance as well as in the immunological status. The changes are most probably due to changes also found in the organ functions. The present work together with earlier investigations by the authors has formed the scientific background for the use of acid preserved fish silage in mink during the last 10 years. This has made it possible to out-distance the competitors further, both with respect to fur quality and feeding costs.

Absorption of NPH-insulin from subcutaneous tissue: a methodological study in pigs

To elucidate the validity of the indirect method of following insulin absorption from the subcutaneous tissue, i.e. external counting of injected 125-I insulin, the disappearance of 125-I NPH insulin from subcutaneous tissue was measured by a biotelemetric method (external measurement of radioactivity) and by direct determination of radioactivity and insulin in subcutaneous tissue extracted one to 300 min. after injection of 8 units 125-I NPH porcine insulin, 5 mm beneath the surface of the skin in 6 anaesthesized pigs. Furthermore, the appearance of insulin in arterial plasma was measured after inhibiting the endogenous insulin secretion of the pigs by epinephrine and propanolol. The disappearance of radioactivity measured continuously for 5 hours was of first order kinetics with t1/2=462+/-36 min. (mean+/-S.E.M.). The half-life of the injected depot of radioactivity (t1/2) demonstrated a large intra- as well as interindividual variation as seen in diabetics. In tissue extracts a highly significant (2P less than 0.001) correlation was found between radioactivity and insulin (r=0.93), indicating the radioactivity to be representative of insulin. During gel chromatography on Sephadex G 50 M only one peak of radioactivity was seen in all tissue extracts. 300 min. after NPH-insulin injection, however, the specific radioactivity of insulin was significantly higher (2P less than 0.05) than in tissue extracts sampled one min. after NPH insulin injection, indicating a slight accumulation of non-immunoreactive insulin degradation products. A fair correlation (r=0.75, 2 P less than 0.05) was seen between the disappearance of externally measured radioactivity or insulin from tissue extracts and the appearance of insulin in plasma. It is concluded that the insulin absorption coefficient is a relevant and biologically sensible expression of insulin absorption.

Comparison of intraperitoneal, intraportal and intravenous insulin infusion

In order to avoid complications induced by long-term infusion of insulin into the portal vein, we examined the effect of intraperitoneal (ip) insulin infusion on arterial plasma insulin and glucose concentrations in 6 pigs, made diabetic by a constant intravenous (iv) infusion of glucose, epinephrine and propranolol. Insulin was infused by an electromechanical programmable mini-pump (Pharmaject Micro Infusion System, Pharmacia Electronics) as a booster injection of 46 mU highly purified porcine insulin Leo/kg body weight, followed by 3 infusion periods of 30 min each with stepwise decreasing rates of 1.6--0.8 and 0.2 mU/kg/min in a total volume of 192 microliters. Insulin was infused in a peripheral vein, a portal vein and into the peritoneal cavity. A steep rise of arterial plasma insulin was demonstrated followed by a slow and identical decline in the peripheral and portal experiments, whereas only a small increase of plasma insulin was seen in the ip experiment, indicating insufficient absorption of insulin from the peritoneal cavity. The decrease of plasma glucose was identical in the peripheral and portal vein experiments, indicating that insulin infused in the portal vein does not seem to have a higher hypoglycaemic effect, than insulin infused in a peripheral vein. Intraperitoneal insulin infusion seems not to be a practical substitute for iv insulin infusion.

Acid-base status of porcine blood during storage

The changes in pH, pCO2, pO2, BE and SBC during storage of venous porcine blood during 24 hours at different temperatures were measured (Table I) and illustrated in Fig 1. Correction table (Table III) for determination of the initial acid-base data are constructed based upon the regression equations in Table II. The changes in the acid-base values of swine blood differ from that of bovine, equine, and canine blood (Table IV).

Acid-base status of mink blood during storage

The changes in pH, pCO2, pO2, BE, and SBC during storage of anaerobic drawn arterial blood for 24 hours at different temperatures were measured (Table Ia, Ib) and illustrated (Fig. 1). Correction tables (Table III) for determination of the initial acid-base data are constructed based upon the regression equations in Table II. The changes in the acid-base values of mink blood are much higher than in equine, porcine, and canine blood during storage at 21-24 degrees C and 0-4 degrees C for 24 hours.

Acid-base status of equine blood during storage

The changes in pH, pCO2, pO2, BE, SBC, and lactic during storage of equine venous and arterial blood in 24 hours at different temperatures were measured (tables I, II), and illustrated (fig, 1, 2, 3). Correction tables (tables VI, VII) for determination of the initial acid-base data are constructed based on regression equations (tables IV, V) of the in vitro changes of the blood. The changes in the acid-base values of equine blood differ from that of bovine and canine blood (table III).

Acid-base status of canine blood during storage

The changes in pH, pCO2, pO2, based excess, standard bicarbonate and lactic acid during storage of canine blood 24 hours at different temperatures were measured (table I a, b) and illustrated (figs. 1 and 2). A correction table (table V) for determination of the initial acid-base data is constructed based upon regression equations (table IV) of the in vitro changes during storage of the blood. The changes in the acid-base values of canine blood differ from that of bovine and human blood (tables II and III).

The influence of the pH of feed on the acid-base balance of mink

The acid-base balance in small carnivores (mink, Mustela vison) was examined during 6 feeding periods, when the same animals were given different feeds during a prolonged time. The feeds consisted of normal farm feed to which different amounts of sulphuric acid-preserved feed and feed silaged with organic acids were added (Tables I--II). When the pH of the feed was decreased to below 5.5, the acid-base balance of the animals was changed and metabolic acidosis occurred (Tables III--V, Fig. 1). On neutralization of the acid-preserved feed a normal acid-base balance could be maintained. However, the growth of the animals was reduced after prolonged feeding with silage as they lost weight during the following periods (Table vii).

Acid-base status of cattle blood. Sampling and storing

Changes in the acid-base parameters of arterial and venous cattle blood (Figs. 1-3) as well as potassium and lactate concentration in plasma from venous blood (Figs. 4-5) were examined during anaerobic storage of the blood. The blood was stored at two different temperatures (21-24 degrees C and 0-4 degrees C) and was stabilized with either heparin alone or heparin and sodium fluoride. By lowering the storage temperature for heparinized blood the glycolysis processes were inhibited to such an extent that the values of the acid-base parameters did not change during the first 5-6 hours of the storage time. On storage at room temperature pH decreased slowly, but steadily. The values for pCO2 and BE respectively also increased and decreased slowly. On storage at room temperature the changes in the pO2 values of arterial blood (Fig. 2) decreased significantly while the venous pO2 values were nearly steady (Fig. 1). The changes in the pO2 values during storage are thought to be related to the oxygen-dissociation curve. The addition of sodium fluoride (Figs. 3-5) affects a number of the chemical processes of the blood to such an extent that the uncertainty on a single determination becomes very great. On storage of heparinized cattle blood at room temperature the potassium concentration in plasma (Fig. 5) can be determined with good certainty during the first 7 hours of the storage time. Lowering of the storage temperature or addition of sodium fluoride has the effect that the potassium concentration in plasma is changed essentially during storage.

The influence on breeding, production, and acid-base balance when mink are fed on acidified feed

It has been shown, partly in an investigation in which female mink were subject to increasing quantities of acid in their feed, and partly in an investigation of experimental animals which were fed with various concentrations of acid-preserved fishsilage, that there is a marked risk for a change of the acid-base balance to a metabolic acidosis when pH in the feed comes lower than 5. These investigations are also considered to show that mink's reproductive ability and general welfare is considerably affected when fed with large quantities of acid-preserved fish feed over a longer period, possibly because of alterations in the acid base balance. It is possible to reduce or avoid metabolic acidosis in mink by neutralizing silage or feed.

Aetiology and Pathogenesis of abomasal displacement in dairy cattle

A clinical chemical survey is given of the complex of factors which are involved during development of clinically manifest hypotony or atony of the abomasum prior to abomasal displacemnts. The importance of a change in the acid-base balance of the animals is especially stressed as a predisposing factor. The further pathogenesis of abomasal displacement is supposed to follow different ways, according to the feeding and to prevailing periods of indigestion.

Prevention of traumatic indigestion in cattle

The incidence of traumatic indigestion in an industrialised agricultural country, the economic losses due to the disease, and its prevention by use of a permanent reticular magnet are reviewed.