An abattoir survey of pneumonia and pleuritis in slaughter weight swine from 9 selected herds. IV. Bacteriological findings in chronic pneumonic lesions.

A total of 855 pig lungs were collected at slaughter and evaluated macroscopically. Bacteriological examinations were carried out on tissue samples from chronic pleuropneumonic lesions (n = 196) and from chronic bronchopneumonic lesions with suppuration (n = 14). Samples from normal lung tissue (n = 22) were also included. Pasteurella multocida was isolated from 54%, Actinobacillus (Haemophilus) pleuropneumoniae from 11%, and Streptococcus spp. from 14% of the pneumonic lesions, respectively. From normal lung tissue P. multocida was isolated from 3 (14%) of the samples, A. pleuropneumoniae was not recovered and streptococci were isolated from only 1 (5%) of these samples. The above mentioned bacterial species were recovered either in pure cultures or mixed with various other microbes. A total of 109 P. multocida strains were further characterized by capsular serotyping and testing for production of dermonecrotic toxin. Ninety-nine (91%) of the strains were capsular type A 10 (9%) were type D. Out of the type A and the type D strains 94% and 90% were toxigenic, respectively. Most of the A. pleuropneumoniae strains were serotype 2. Strains of serotypes 1 and 7 were also identified. The majority of the streptococci were identified as either Streptococcus suis or Streptococcus dysgalactiae. Actinomyces pyogenes was isolated from 14% of the lesions and anaerobic bacteria from 18%, respectively. The significance of the various bacterial species in relation to the development of chronic pneumonic lesions is discussed. Special attention is paid to P. multocida, and it is concluded that this bacterial species is probably of importance for the development of both types of chronic pneumonias.     

Screening for infection of Trichinella in red fox (Vulpes vulpes) in Denmark

A total of 6141 foxes (Vulpes vulpes) were examined for infection with Trichinella. The foxes were killed in Denmark during the hunting season 1995-1996 and 1997-1998; 3133 and 3008, respectively. Foxes included in the investigation came from throughout the country with the exception of the island of Bornholm. The right foreleg from each fox was submitted for investigation. The legs were stored at -20 degrees C for 3-10 months prior to examination. Following thawing, muscle tissue (10 g) from each leg was examined by trichinoscopy and by a pepsin-HCl digestion technique. In 1995-1996, three foxes were found positive corresponding to a prevalence of 0.001. Each of the infected foxes harboured an extremely low infection, i.e. about one larva per 10 g muscle tissue. It was not possible to obtain sufficient larval material for species identification. All three foxes were shot in the vicinity of a small village in the north-western part of Denmark. In 1997-1998 no Trichinella cases were found. The results, compared with previous studies, indicate that the prevalence of infection of Trichinella sp. among wild living foxes in Denmark is very low. This is further supported by the fact, that no infection of Trichinella sp. has been found in slaughtered pigs in Denmark for more than 65 years, which suggests that the infection pressure is very low. Considering the facts above we conclude that the risk of Trichinella infections is negligible in intensive indoor pig production units in Denmark whereas high local prevalence of Trichinella infections in the wildlife might constitute a serious risk for the expanding outdoor pig production.     

Genetic basis of penicillin resistance of S. aureus isolated in bovine mastitis

Background

The blaZ gene encoding penicillin resistance can be located either chromosomally or on plasmids. The aim of this study was to investigate the genetic relationships and to determine the location of the blaZ gene in S. aureus isolated in bovine mastitis in Finland and Sweden.

Methods

Seventy-eight β-lactamase positive S. aureus isolates from bovine mastitis (34 from Finland and 44 from Sweden) were included in the study. The localization of blaZ gene was determined by Southern blotting. The blaZ genes of the isolates were sequenced and the sequences were translated to beta-lactamase proteins and further grouped as different protein signatures. The isolates and, as control, 33 Swedish and 36 Finnish beta-lactamase negative isolates were typed with pulsed-field gel electrophoresis (PFGE).

Results

In 26 out of 34 Finnish isolates (76.5%) and in 25 out of 44 Swedish isolates (56.8%) the blaZ gene was localized on a plasmid. Six different protein signatures were found. One signature was found only in four Swedish isolates, but all other signatures were found both in Finnish and Swedish isolates. The PFGE results revealed a diversity of S. aureus clones. The protein signatures were not clearly associated with certain pulsotypes.

Conclusions

The plasmid location of the blaZ gene was not statistically significantly more common in Finland than in Sweden, and hence does not explain the higher proportion of penicillin-resistant isolates of S. aureus causing bovine mastitis in Finland compared to Sweden.     

Growth performance,nutrient digestibility and intestinal morphology of rainbow trout (Oncorhynchus mykiss) fed graded levels of the yeasts Saccharomyces cerevisiae and Wickerhamomyces anomalus

In a 10‐week study, we evaluated the effects of replacing 20%, 40% or 60% of fishmeal (present in control diet at 300 g/kg) on a digestible protein basis with yeast Saccharomyces cerevisiae or a yeast mixture of Wickerhamomyces anomalus and S. cerevisiae on growth performance, nutrient digestibility, nutrient retention and intestinal health of rainbow trout (Oncorhynchus mykiss). Triplicate tanks with 35 rainbow trout (144.7 ± 25.1 g mean ± SEM) were fed rations of 1.5% of total biomass per tank. Replacement of 60% of fishmeal with yeast mixture resulted in lower specific growth rate of 1.0% versus 1.2%/day for other diets. Apparent digestibility coefficients for crude protein and most amino acids were highest in fish fed fishmeal‐based diet, with similar values for fish fed the diet with 20% replacement with yeast mixture. Diet with 20% replacement with yeast mixture resulted in highest phosphorus digestibility. Replacement of 60% of fishmeal with S. cerevisiae resulted in oedematous mucosal fold tips in the proximal intestine. The results of this study suggest that these yeasts can replace up to 40% of fishmeal under current inclusion levels in diets for rainbow trout without compromising growth performance, nutrient digestibility or intestinal health.     

Nitrogen effects of non-legume catch crops

Nitrate leaching during the winter period can be reduced and often prevented by growing catch crops after the harvest of a main crop. However, catch crops which effectively take up residual nitrogen do not necessarily show good nutrient effects on a succeeding main crop. The objective of this experiment was to investigate how the content of soil mineral nitrogen in spring was affected by the time of incorporation of non-legume catch crops and how the yield and nitrogen uptake of a succeeding main crop was influenced. The yield of spring sown onion and white cabbage was significantly increased by catch crop growing the previous autumn. The nitrogen effect of Italian ryegrass corresponded to 50–100 kg N per ha in the vegetables. However, the yield of spring barley was not significantly affected by the nitrogen released from decomposing catch crops. During decomposition of non-legume catch crops, grown at a high level of nitrogen fertility, nitrogen immobilization did not occur.     

Liquid chromatographic determination of the estrogens daidzein, formononetin, coumestrol, and equol in bovine blood plasma and urine

A liquid chromatographic (LC) method is described for the determination of the plant estrogens diadzein, formononetin, and coumestrol and the estrogenically active metabolite equol in bovine blood plasma and urine. The blood and urine samples are incubated overnight with and without beta-glucuronidase/sulfatase for analysis of both free and conjugated forms of estrogens. Samples are applied to Extrelut columns, extracted with ethyl acetate, and evaporated to dryness. Residues from urine samples are dissolved in methanol, diluted with water, acidified with HCl, and purified by injection through a Sep-Pak C18 cartridge. This eluate is used for LC analysis. Residues from blood samples are dissolved in benzene-petroleum ether (1 + 1), extracted with ammonium hydroxide, acidified with glacial acetic acid, and extracted with ethyl acetate. The ethyl acetate extract is evaporated, dissolved in 80% methanol, injected onto a LC reverse-phase column, and separated in a linear gradient system between 40 and 80% methanol in phosphate buffer. Quantitation is performed by means of UV and fluorescence responses. The method was sensitive enough to determine 0.4 ng/mL of daidzein and formononetin and 0.1 and 13 ng/mL of coumestrol and equol, respectively, in blood, and 130, 80, and 7 ng/mL of daidzein, formononetin, and coumestrol, respectively, and 4 micrograms/mL of equol in urine. The applicability of the method was checked by the determination of total and free plant estrogens in blood samples from a dairy cow fed a normal diet.     

Planktonic and Littoral Microcrustaceans as Indices of Recovery in Limed Lakes in SE Norway

A two year study of planktonic and littoral microcrustaceans (Cladocera and Copepoda) from 15 lakes in the southeastern part of Norway, Østfold county, document the recovery of acidified lakes due to liming. Six lakes that where limed about 10 years ago, seven acid and two neutral reference lakes, were sampled twice a year (1998 and 1999). One acid lake was limed in autumn 1998. Qualitative nethaul samples from the deepest part of the lake and from the most frequent habitat in the littoral zone were used. The limed lakes had a species composition which indicates that these lakes are about to recover. Species associated with neutral lakes dominates while acid-tolerant species were rare. The acid-sensitive species, Daphnia longispina and D. cristata, were found in the limed lakes. This study shows the usefulness of a low-cost sampling program where microcrustaceans are used as bioindicators of recovery.     

Acidic deposition and its effects in southwestern China

The emissions of SO₂ in China correspond at present to 8–10 TgSyr^?1. The rapid industrialization has caused a dramatic increase in the emissions in recent years and this increase is likely to continue. This paper describes studies of concentrations and effects of acidifying substances in parts of the Guizhou and the Sichuan provinces where the S-emissions are large. A small catchment about 10 km from Guiyang centre was equipped with instruments for studies of soils, soil water and streamwater chemistry. The molar ratio Al/(Ca+Mg) is > 0.8 in soil water in some places. Two small streams have median pH-values about 4.6 and 5.1. Laboratory studies with selected Chinese soils showed that the anion adsorption was low. These studies gave also important information on soil sensitivity. The studies confirm that acid deposition may affect soils in parts of south-western China, but the sensitivity varies dramatically and there is a strong need for more information.     

Deciphering the reaction dynamics underlying optimal control laser fields

Femtosecond high-resolution pump-probe experiments have been used together with theoretical ab initio quantum calculations and wave packet dynamics simulations to decode an optimal femtosecond pulse that is generated from adaptive learning algorithms. This pulse is designed to maximize the yield of the organometallic ion CpMn(CO)3 while hindering the competing fragmentation. The sequential excitation and ionization of the target ion are accomplished by an optimized field consisting of two dominant subpulses with optimal frequencies and time delays.