Methods to evaluate pesticide damage to the biomass of the soil microflora

Respiratory methods to estimate the amount of C in the soil microbial biomass and the relative contributions of procaryotes and eucaryotes to the biomass were used to evaluate the influence of pesticides on the soil microflora. Experiments were conducted with 5 and 50 μg·g^?1 of three fungicides, captan, thiram and verdasan. At 5 μg·g^?1 they caused significant decreases (40%) in the biomass; the organomercury fungicide verdasan also caused a shift from fungal to bacterial dominance. Within 8 days, biomass in captan- and thiram-amended soils had recovered to that of the controls. Although the fungal to bacterial balance was restored in verdasan-amended soils, biomass recovery was not complete. At 50 μg·g^?1 the fungicides caused long-term decreases in the biomass and altered the relative proportions of the bacterial and fungal populations. Verdasan had the greatest effect on soil microbial biomass and composition.     

Determination of N-nitrosodimethylamine levels in some Canadian 2,4-D amine formulations

Levels of N-nitrosodimethylamine (NDMA) were determined in 112 samples of 2,4-dichlorophenoxyacetic acid, (2,4-D), formulated as the dimethylamine salt, collected over a 2 year period from products on the Canadian market. A sample aliquot is partitioned with dichloromethane, and the co-extracted dimethylamine is removed by cleanup on a silica gel column. The eluates containing NDMA are concentrated, an internal standard of N-nitrosodipropylamine is added, and nitrosamine levels are determined using a gas chromatograph interfaced with a thermal energy analyzer. Recoveries of NDMA and N-nitrosodiethylamine spiked into samples were 103 +/- 16 and 96.3 +/- 9.8%, respectively. Of the 112 samples analyzed, 92 were below 1 part per million (ppm) relative to the amount of 2,4-D in the samples, 16 were between 1 and 5 ppm, and 4 were greater than 5 ppm. The gas chromatographic column used is compared to a conventional packing material for volatile nitrosamine analysis. Formation of NDMA during cleanup and analysis was shown not to occur.     

Isolated fracture of the radial diaphysis in dogs

Four cases of isolated fracture of the radial diaphysis were diagnosed. All cases were successfully managed conservatively. Direct trauma was not a feature in any of the cases. The history, presenting signs and fracture morphology in each case were similar suggesting a common aetiology. The case histories are reviewed and a possible aetiology discussed.     

Etiologic studies on late-term swine abortions

One hundred thirty-eight swine abortions were studied in detail in an effort to identify an etiologic agent. A viral agent was implicated in 7 cases. Bacteria were isolated in less than half of the examined cases: however, in 61% of the cases, motile, filamentous organisms were observed in tissues and fluids. Although swine sera from farms experiencing reproductive problems had a high reactor rate to Leptospira bratislava antigen, electron microscopy of the observed organism revealed a wall-free prokaryote morphologically typical of the class Mollicutes.     

Body condition of sows across parities and relationship to reproductive performance

Weight, heartgirth, backfat and body condition of sows was monitored in a commercial, farrow-to-finish unit during 1 yr. Measurements were obtained during the third, ninth and fifteenth week of gestation and the day after weaning. Litter performance and rebreeding rate also were recorded. Body weight and heartgirth increased (P less than .01) over parities because gestational gains were larger than lactational losses. Backfat tended to be lower in later parities. Body weight, heartgirth and backfat, but not condition score, declined from weaning to the third week of the subsequent gestation in both first and second litter sows. Correlations among measures of body condition were low (less than .45), except the overall correlation between body weight and heartgirth. Number of pigs born alive increased and interval to estrus decreased in later parities. There were no significant relationships between changes in body condition and rebreeding performance of sows. These results suggest that changes in body condition typically observed in sows housed in commercial production units may be too subtle to have an effect on reproductive performance.     

Variations in muscle fiber composition between successfully and unsuccessfully raced quarter horses

Muscle biopsy samples were removed from the m gluteus medius of 47 retired running Quarter Horse (QH) mares. Horses were separated based on bloodline, past racing history and percentage Thoroughbred (TB). The bred to run and raced (BRRA) and bred to run and not raced (BRNR) groups possessed a lower percentage (P<.01) of fast-twitch low oxidative (FT) fibers (BRRA 38.6 and BRNR 36.2±2.54 respectively). These horses also possessed a higher percentage (P<.01) of fast-twitch high oxidative (FTH) fibers (BRRA 52.5 and BRNR 48.5±2.54, respectively) than not bred to run and not raced (NBNR) horses. Horses that were bred to run had higher (P<.05) FTH to FT fiber ratios (1.44) than horses that were not bred to run (.94). Successful racehorses possessed a lower percentage (P<.05) of slow-twitch (ST) fibers and a higher percentage (P<.05) of FT fibers than unsuccessful racehorses. Success or failure was determined by Speed Index. No differences (P>.05) were found in the percentage FTH fibers between successful and unsuccessful horses.     

Clinical and pathological responses of weaned pigs to atmospheric ammonia and dust

Nine hundred and sixty weaned pigs were exposed for five weeks to controlled concentrations of atmospheric ammonia and dust in a single, multifactorial experiment. The treatments were a mean dust concentration of either 1.2, 2.7, 5.1 or 9.9 mg/m3 (inhalable fraction) and a mean ammonia concentration of either 0.6, 10.0, 18.8 or 37.0 ppm, concentrations representative of commercial conditions. The experiment was carried out over two years and the pigs were used in eight batches, each consisting of five lots of 24 pigs. Each treatment combination was replicated once, and an additional control lot (nominally 0 mg/m3 dust and 0 ppm ammonia) was included in each batch. The dust concentration was the same in the other four lots in each batch in which the four concentrations of ammonia were used; thus, the split-plot design was more sensitive to the effects of ammonia than dust. The groups of pigs were kept separately in five rooms in a purpose-built facility, and the pollutants were injected continuously into the air supply. Ammonia was supplied from a pressurised cylinder, and the endogenous dust in each room was supplemented by an artificial dust manufactured from feed, barley straw and faeces, mixed by weight in the proportions 5:1:4; its ingredients were oven-dried, milled and mixed, and then resuspended in the air supply. The health of the pigs was assessed in terms of general pathology, respiratory tract pathology, and the microbiology of the nasal cavity, trachea and lung. In each batch, postmortem examinations were carried out on 40 pigs after five weeks' exposure to the pollutants and on 30 pigs two weeks later to test for carryover and recovery--a total of 560 pigs. These examinations revealed minimal gross pathology and widespread minor pathological changes of little significance. The pigs' turbinate and lung scores were low and unaffected by exposure to pollutants. All the putative bacterial pathogens, with the exception of toxigenic Pasteurella multocida type D, were isolated from the respiratory tract of the pigs of both ages, but there were no differences between the effects of the different concentrations of pollutants.     

Effect of adrenalectomy in the dog on blood gas tensions and oxygen content.

Arterial and venous blood gas tensions and pH were determined in 8 dogs during a control interval, while adrenal deficient, and following replacement therapy with corticosteroids. Additionally, erythrocyte 2,3-diphosphoglycerate (DPG) values were measured, and oxygen tension (mm of Hg) when hemoglobin is half-saturated with oxygen (P50) values were calculated. Mixed venous oxygen tension (PVO2), but not arterial oxygen tension (Pao2), decreased significantly (P less than 0.001) during adrenal insufficiency. This change was reflected in a significantly decreased (P less than 0.001) venous oxygen content and a significant increase (P less than 0.001) of the arterial-venous oxygen content difference. Other changes during adrenal insufficiency were nonsignificant decreases in DPG and P50 values. Treatment with corticosteroids for 2 to 3 days resulted in a significant (P less than 0.001) increase in DPG concentrations, a significant (P less than 0.025) increase in P50, and a reduction in the arterial-venous oxygen content difference compared with those values found in the adrenal-deficient dog.