Effect of DDT, intensive use of the floor surface and post-incubation stress on the development of immune response in chickens]

We studied the long-term effect of civilization factors, DDT, high stocking rates, and post-incubation stress on the antibody response to the administration of Newcastle disease vaccine. The chickens were divided into three groups after hatching. The first group was fed a mixture with an addition of commercial DDT (100 mg per 1 kg of feed). The second group was given the same feed and, in addition, was kept at a high stocking rate. Half the experimental chickens of each group were tied in the third post-natal week, to subject the birds to another stress. Those in the control group remained intact. The results indicate that DDT administered with food increased the immunity response to the antigen stimulus. The additive stress from high stock densities reduced the immunity response, and decreased the response raised by DDT administration to the level of the control. The post-incubation stress was found to modify the long-term effect of DDT and high stocking rate upon the immunity response of the chickens.     

Vergleich von Methoden zur Bestimmung der Wurzellängendichte bei Kulturpflanzen

Comparison of methods to determine the root length density of crops
In this paper, in a first step a comparison of the soil core or monolith method with the profile wall method was undertaken with data obtained for sugar beets.
Results show that differences between both methods, expressed as a factor, decline destinctly during the vegetation period. This means that the calibration of the profile wall method with the help of a time independent, average factor cannot be recommended.
In a second step, we compared the monolith method with a new procedure to estimate root growth.
Results for a soil derived from loess show that values measured and estimated correspond very well, while for a sandy soil, there was only a satisfactory correspondence.
The comparison led to the conclusion, that in field work the monolith method should be preferred to the profile wall method, and the root growth estimation procedure is available alternative to determine the root length density of cereals.     

Long-term study of incidence and financial loss due to cattle babesiosis in an Argentinian dairy farm

The incidence and direct financial loss caused by babesiosis were evaluated in 121 Holstein Friesian female cattle that formed eight cohorts (1981–1988) of a dairy farm located approximately 24° 55′S 65° 29′W in Salta, Argentina. Female calves born in 1986 and 1987 (n=32) were vaccinated with a live Babesia vaccine at six months of age.

No cases of babesiosis occurred in the vaccinated cattle. The incidence of babesiosis in the six non-vaccinated cohorts was 23.6% (21/89). Eighteen of the cases were the result of Babesia bovis, one to Babesia bigemina and two to a mixed infection. Two cattle died of B. bovis infection in spite of drug treatment (diaminazene, 3.5 mg kg⁻¹). No disease occurred in cattle younger than seven months or older than 24 months. The number of cases according to age of cattle was: 7–9 months, 5; 10–12 months, 6; 13–24 months, 10.

Financial loss for the six cohorts that suffered clinical cases amounted to US $ 1624.6 (prices in October 1990)—62% were the result of physical losses and 38% to costs of control. A benefit-cost analysis of vaccination was carried out assuming that 95% of the mortality and morbidity losses of the six non-vaccinated cohorts was prevented after a single inculation of a live vaccine (cost of a dose plus administration was US $ 4.2. The benefit-cost ratio was 4:1 for each US dollar expended.     

Phenotypic and genetic characterization of enteropathogenic Escherichia coli (EPEC) and entero-aggregative E. coli (EAEC) from diarrhoeal and non-diarrhoeal children in Libya

A total of 50 Escherichia coli strains isolated in a Libyan hospital (20 from children with diarrhoea and 30 from healthy children) were investigated for their pathotypes and virulence traits. Altogether nine eae-positive (enteropathogenic E. coli, EPEC) and nine aggR-positive (entero-aggregative E. coli, EAEC) strains were identified. Significantly (P=0.001) more EPEC strains were identified from diarrhoeal patients (n=8) than from healthy controls (n=1), while six EAEC strains were identified from diarrhoeal and three from healthy children. Typical (eae(+), EAF(+), bfp(+)) EPEC strains (n=6) belonged to classical EPEC serogroups O55, O114, O127 and showed localized adherence on Hela cells. EAEC strains revealed genetic heterogeneity but uniformly adhered to HeLa cultures in an entero-aggregative adherence pattern. Antibiotic resistance frequently, characterized the strains. Sixty-eight percentage of the strains were resistant against at least one antibiotic and 30% harbored a class 1 integron independently of their clinical background. This is the first report from North Africa demonstrating the significance of EPEC and EAEC.     

Valorization of biomass: deriving more value from waste

Most of the carbon-based compounds currently manufactured by the chemical industry are derived from petroleum. The rising cost and dwindling supply of oil have been focusing attention on possible routes to making chemicals, fuels, and solvents from biomass instead. In this context, many recent studies have assessed the relative merits of applying different dedicated crops to chemical production. Here, we highlight the opportunities for diverting existing residual biomass--the by-products of present agricultural and food-processing streams--to this end.     

Colonisation of conventional weaned pigs by enteropathogenic Escherichia coli (EPEC) and its hazard potential for human health

Enteropathogenic Escherichia coli (EPEC) bacteria frequently cause severe enteric diseases primarily in children and in young rabbits. Their pathogenicity for pigs has been tested by oral infection of colostrum-deprived newborn, and of severely immunosuppressed weaned pigs, but colonisation of conventional weaned pigs by porcine EPEC has not been experimentally studied. EPEC show similarities to enterohaemorrhagic E. coli (EHEC) additionally carrying shiga toxin genes integrated into the chromosome by lambdoid phages. We have demonstrated earlier that the porcine EPEC prototype strain P86-1390 (O45) could be transduced in vivo (in ligated loops of weaned pigs), by Stx2 phage derived from a human EHEC. Thus, the ability of this porcine EPEC strain to colonise conventional weaned pigs under farming conditions became a question of relevance to human health. To clarify this question, four intragastric infection experiments were performed on a total of 95 conventional weaned pigs. The EPEC P86-1390 and other well-characterised porcine EPEC strains were applied to 54 pigs, leaving 41 weaned pigs as negative controls. In three experiments moderate predispositions were applied: coinfections with enterotoxigenic E. coli (ETEC) or with low-virulence TGE coronavirus, application of fumonisin B1 with a normal therapeutic dose of dexamethasone, and the increase of soybean protein concentration in the feed. A total of 41 weaned pigs served as negative controls inoculated with a commensal porcine E. coli. Housing conditions simulated the farm environment. As an overall result, ileal segments of 18.5% of infected pigs were shown to be colonised by EPEC, while no EPEC were detected in the ilea of controls. Among predisposing factors occurring on farms, feed protein content increased by 20% (26.3% crude protein, provided by 48% soybean meal) seemed to enhance EPEC colonisation and resulted in the mobilisation of spontaneous latent EPEC/ETEC infection. The results indicate that under normal farm conditions porcine EPEC may colonise conventional weaned pigs by inducing ileal attaching effacing (AE) lesions with reasonable frequency, without clinical signs. The results also suggest that conventional weaned pigs may represent undetected reservoirs of porcine EPEC, potentially giving rise to the emergence of new types of EHEC due to natural transduction by Stx phages.     

Limited genetic diversity of Aerococcus viridans strains isolated from clinical and subclinical cases of bovine mastitis in Slovakia

The Aerococcus viridans isolates from bovine mastitis in Slovakia were isolated and characterized by classical microbiological and biochemical, and molecular techniques including IGS-PCR and rep-PCR, ARDRA and 16S rDNA gene sequencing. The substantial variability of antibiotic resistance patterns was observed. The majority of strains were resistant to beta-lactam antibiotics, the resistance to tetracycline was observed in 3 tested strains, resistance to lincomycin was found in 4 strains and practically all tested strains were sensitive to neomycin and ciprofloxacin. While variable at a phenotypic level, no significant genetic variability among A. viridans isolates was detected by molecular DNA based methods. The data obtained suggest that a few A. viridans strains spread among cow's population in Slovak farms.     

Citric acid extraction—An underestimated method in forest nutrition?

Since recent studies reveal citric acid to be favorable for estimating plant‐available P in soils, we investigated if it can also be used for assessing other nutrients. According to our results, it provides stronger correlations with the tree nutrition for Mg (beech, spruce), Ca+K (beech) and Fe (spruce) than the standard methods for determining exchangeable cations. Thus, when estimating plant‐available P by citric acid‐extraction, these cations should be additionally measured in ICP analysis.