Changes in the free amino acid content of soil following treatment with fungicides

Both quantitative and qualitative changes in the free amino acid content of soil followed treatment with the fungicides Benomyl, Thiram and Verdasan. The amounts of amino acid-N extracted following the additions of high concentrations of the fungicides were in general lower than the controls over the 28-day incubation period. Low rates of application however, resulted in marked increase in the amounts of amino acid-N extracted. A total of nine different amino acids were extracted seven of which were found consistently in the control soils. Glycine and threonine were markedly favoured by all treatments, whereas the frequency of extraction of the other seven amino acids was dependent upon the fungicide used and its concentration. The results are discussed in relation to the changes in the microbiology of soils which are known to be brought about following partial sterilization with fungicides.     

Influence of soybean hull supplementation on rumen fermentation and digestibility in steers consuming freshly clipped, endophyte-infected tall fescue

Six steers (288.6 +/- 2.1 kg of BW) fitted with rumen and duodenal cannulas were used in a crossover design to evaluate intake, rumen fermentation, and site of nutrient digestion of freshly clipped, endophyte-infected (E+) Kentucky 31 tall fescue with or without soybean hull (SH) supplementation at 0.60% of BW (OM basis). Steers were placed in metabolism units within an environmentally controlled room and provided with free-choice access to fresh forage, water, and a vitamin/mineral supplement. The spring growth of E+ tall fescue was harvested daily during the experiment. Supplement was fed at 0700 with approximately 65% of the estimated daily forage. To maintain a fresh forage supply, additional forage was stored in a cooler and fed at 1900. Periods were 21 d with 14 d of adaptation and 7 d of digesta sample collection. Chromic oxide was used as a marker of duodenal digesta flow. Duodenal samples were taken 4 times daily with times shifting by 1 h each day to represent all 24 h of a day. Treatments were considered significant at P < 0.05. Supplementation of SH decreased forage OM intake from 1.64 to 1.41% of BW but increased total OM intake from 1.64 to 2.01% of BW. Apparent percentages (53.1%) and quantities (2,786 g/d) of rumen OM disappearance were not affected by supplementation. Percentages of total tract OM disappearance were not different (70.8%). Percentages of apparent rumen NDF disappearance also were not different (65.6%). Percentages of N disappearance were not different. Supplementation of SH resulted in increased total N (34.1 g/d) and microbial N (17.1 g/d) flowing to the duodenum. Rumen pH (6.5) was not affected, and rumen ammonia concentrations exhibited a time x treatment interaction in which SH decreased ammonia for 12 h after supplementation. Total VFA concentrations (103.9 mM) were unaffected. Liquid dilution rate (12.7%/h) and rumen OM fill (4.3 kg) were not different between treatments. Supplementation of SH at a rate of 0.60% of BW (OM basis) to calves consuming fresh E+ tall fescue decreased forage consumption but resulted in greater total intake, greater flow of N to the duodenum, and increased total tract OM disappearance.     

COMPARATIVE EVALUATION OF AN ULTRAVIOLET AND AN ORTHOCHROMATIC RARE-EARTH IMAGING SYSTEM FOR VETERINARY RADIOGRAPHY

The relative quality and speed of a new ultraviolet-emitting screen, ultraviolet-sensitive film rare-earth system (DuPont Ultra-Vision®) was compared to an orthochromatic rare-earth system (Kodak Lanex®) in a clinical trial. Seven different sets of radiographs of a human foot phantom, or actual canine anatomical structures (tarsus, pelvis, skull, chest, abdomen) were evaluated independently by radiologists, radiology residents and technicians who were unaware of the screen/film combinations used. The 400-speed, Ultra-Vision® Rapid/UVG screen/film combination produced supervisor image detail compared to blue/green emitting 400 and 200-speed screen/film combinations. The image detail of the Ultra-Vision® Rapid/UVG system was nearly equivalent to that produced using a 100-speed, fine-detail blue/green emitting screen/film combination. A 200-speed Ultra-Vision® system was also tested and produced thoracic and abdominal radiographs of equivalent to slightly supervisor quality than those produced using blue/green emitting system.     

Infectious bovine keratoconjunctivitis: experimental induction of infection in calves with mycoplasmas and Moraxella bovis.

Eyes of 14 calves were exposed by conjunctival instillation to cultures of either Mycoplasma conjunctivae (6 calves) or Acholeplasma laidlawii (8 calves). Calves were observed for clinical signs of infectious bovine keratoconjunctivitis (IBK), and eyes were examined for the test organisms by bacteriologic cultural technique for 60 days. Acholeplasma laidlawii became established in the eyes of 5 of 8 calves; M conjunctivae became established in the eyes of 4 of 6 calves. On day 28, eyes of 9 of the 14 calves were exposed by conjunctival instillation to Moraxella bovis, and all developed IBK. Five calves exposed to Moraxenjunctivae or A laidlawii, but not to Mor bovis, did not develop IBK. Four calves not exposed to M conjunctivae or A laidlawii, but exposed to Mor bovis, developed IBK. Mycoplasmas do not have a major role in IBK, but might produce ancillary effects similar to those of infectious bovine rhinotracheitis virus, wind, ultraviolet radiation, dust, and other irritants.     

Infectious bovine keratoconjunctivitis: comparison of infection, signs of disease and weight gain in vaccinated versus nonvaccinated purebred Hereford heifer calves.

To determine whether the carrier state of Moraxella bovis could be prevented under natural conditions of exposure by vaccination, purebred Hereford calves were vaccinated twice; once in June 1982, and again in September 1982. Eyes of calves were examined for signs of infectious bovine keratoconjunctivitis (IBK) and cultured for M. bovis in June 1982, September 1982, January 1983 and June 1983. When calves were compared on the basis of selection lines (four genetic groups), there were significant (P less than 0.05) differences in the percentages of infection, disease and weight gain between selection line calves, regardless of their vaccination status. Results suggest that vaccination, in conjunction with clinical infectious, bovine keratoconjunctivitis, reduces the carrier state of M. bovis in the herd but the immunity lasted less than 9 months. The disproportionate representation of the most genetically resistant calves among nonvaccinated calves probably accounted for the equivocal results between vaccinated and nonvaccinated calves.     

Cellulose-decomposing fungi in polder soils and their possible influence on pathogenic fungi

For a study of the colonisation of the IJsselmeerpolders by fungi, attention was fixed on the cellulose-decomposing fungi, since these are considered to represent the more stable part of the mycoflora of soils. If one assumes that in the North East Polder, cultivated for approximately 25 years, the fungal population is approaching stability, the progress of colonisation of the younger polders can be judged by comparison of the number of species found and their frequency.It is shown that the progress of fungal colonisation did not depend only on the time during which a soil has been dry, but also on the use that has been made of it. Of the species known as antagonists of other fungi,Trichoderma spp. provided an increasingly larger proportion of the total population as the soils were further from stability.It is concluded that the increase of fungal antagonists may well be one of the causes of the decline of such parasites asOphiobolus graminis andRhizoctonia solani. Special mention is made ofGliocladium roseum, the parasitism of which towardsR. solani could be demonstrated in paired cultures.