Specificity of inhibition between Salmonella strains

A phenomenon of inhibition among Salmonella organisms colonizing the gut of young animals can be demonstrated which is important in connection with immunization using live Salmonella vaccines. For practical utilization of this inhibition phenomenon, research into its specificity is very important. In vitro broth culture and animal experiments have shown inhibition to be genus-specific, i.e. there is no inhibition between strains of different genera of Enterobacteriaceae in most cases. The strongest inhibition occurs between isogenic (identical genotype) strains (strain-specific inhibition). This applies to Salmonella and other genera of Enterobacteriaceae. There was a close correlation between the degree of the inhibitory effect and the genetic relatedness of the strains, as has been demonstrated in Salmonella strains of different epidemiological classification. The inhibitory capacity was most pronounced among closely related strains. Clonal strains of Salmonella Enteritidis phage type 4 fully inhibited caecal colonization by Salmonella Enteritidis phage type 4 strains in 65% of the combinations tested in chicks. In broth culture experiments, the share of combinations with complete inhibition was above 90%. A significant inhibitory competence of a selected strongly inhibitory Salmonella Enteritidis phage type 4 strain against the majority of Salmonella Enteritidis field isolates can be expected. However, Salmonella Enteritidis strains of all phase types showed almost no inhibitory competence against other Salmonella serotypes.     

Yield and morphological responses of a forage sorghum to mefluidide

Abstract

Due to rapid growth, stem build‐up in forage sorghum crops often leads to considerable wastage by animals and consequent loss of production. In this study the potential of the chemical plant growth regulator, mefluidide, for modifying the morphology of forage sorghum was examined. Mefluidide was applied to two consecutive plantings of forage sorghum at 0; 0,14 and 0,28 kg/ha. Treatment with mefluidide suppressed stem elongation of sorghum plants and stimulated tillering 4–6 weeks after application. After 6 weeks the stem:leaf ratio of treated plants was significantly lower (P ≤0,05) than that of control plants. On average, total dry matter (DM) yield was marginally higher for the control, but DM yield of leaf material was significantly higher. (P ≤0,05) for treated plots from 6 weeks after mefluidide application. No significant differences were observed between levels of mefluidide but responses of different variables over time differed between plantings. This was associated with different stages of plant growth when mefluidide was applied and different environmental conditions for two plantings.     

The influence of intramammary antibiotic treatment, presence of bacteria, stage of lactation and parity in dairy goats as measured by the California Milk Cell Test and somatic cell counts

The California Milk Cell Test (CMCT) and somatic cell counts (SCC) on their own were not reliable methods in the identification of subclinical mastitis in the dairy goats studied and should be accompanied by microbiological tests. However, CMCT and SCC were indicators of irritation of the udder parenchyma. In healthy goats Spectrazol Milking Cow (Schering-Plough AH) caused the least and Curaclox LC (Norbrook (ARK AH)) the most irritation of parenchyma after intramammary treatment. The effects of Rilexine 200 LC (Logos Agvet (Virbac)) were intermediate. There was a highly significant difference (P < 0.001) in the mean log SCC between treated and control groups for goats treated with Curaclox LC and Rilexine 200 LC but no significant difference was present in the mean log SCC of treatment and control groups for goats treated with Spectrazol Milking Cow at the 07:00 and at 19:00 samplings. The CMCT was an indicator of the level of SCC in goat milk. The CMCT was more useful in confirming the absence of infection, rather than in diagnosing mastitis.     

Effects of transcutaneous electrical nerve stimulation on the fatty acid profile of rabbit longissimus dorsi muscle (preliminary report)

This study was designed to investigate whether transcutaneous electrical nerve stimulation (TENS) of the longissimus dorsi muscle (MLD) of rabbits induces specific proportional changes in the muscle fatty acid composition. Ten 4-week-old Pannon White rabbits were exposed to TENS treatment two times a day, with the following settings: 30 Hz, 20 micros impulse length, 10 mA, 2 x 20 min. After a treatment period of 50 days rabbits were slaughtered and the fatty acid composition of the MLD was determined by gas chromatography. The TENS treatment increased the proportions of linoleic (C18:2 n-6), linolenic (C18:3 n-3) and gondoic acids (C20:1 n-9), compared with the control group. The level of palmitic (C16:0), stearic (C18:0), oleic (C18:1 n-9) and eicosapentaenoic (C20:5 n-3) acids significantly decreased. The proportion of total unsaturated fatty acids significantly increased. On the basis of the results obtained, TENS may have similar effects on the muscle fatty acid profile like physical training. Based on the supposal that the composition of membrane structure was also affected, the electrical stimulation of muscles may have further consequences, e.g. on membrane properties.     

Effect of intramammary infusion of beta-1,3-glucan or interleukin-2 on leukocyte subpopulations in mammary glands of sheep.

OBJECTIVE: To investigate effects of intramammary infusion of beta-1,3-glucan or recombinant ovine interleukin-2 (rOvIL-2) on blood and mammary leukocyte subpopulations and their expression of various surface antigens in sheep. ANIMALS: 12 healthy multiparous, nonpregnant, nonlactating fine-wool Merino ewes. PROCEDURE: Beta-1,3-glucan in pyrogen-free saline solution (PFSS; n = 6), rOvIL-2 in PFSS (3), or PFSS (3) was infused on days 0 and 7 in 1 udder half of each ewe. Jugular vein blood and mammary secretion samples were taken before infusion and on days 2, 7, and 21 after infusion. Total and differential leukocyte counts were obtained, and blood and mammary cells were labeled for flow cytometry. RESULTS: Slight swelling of the mammary glands was observed on day 2 after rOvIL-2 but not after beta-1,3-glucan infusion. Both substances induced significant increase in mammary secretion leukocyte numbers, compared with controls. Beta-1,3-Glucan induced an influx of monocyte/macrophages, whereas neutrophils were the predominating cell population after rOvIL-2 infusion. Beta-1,3-glucan induced selection for CD4+, B-cell+, WC1+, and L-selectin+ lymphocytes on day 14 after infusion. By comparison, rOvIL-2 induced selection for B-cell+ and L-selectin+ lymphocytes on days 14 and 21 and depletion of CD8 and, to some degree, of IL-2R+ lymphocytes. Beta-1,3-Glucan induced an increase in the proportion of CD14+ leukocytes, indicating selective migration of monocyte/ macrophages to the nonlactating udder. CONCLUSION: Beta-1,3-Glucan and rOvIL-2 can modulate nonspecific immunity in the udder of sheep but may exert their effects by differing mechanisms. Clinical Relevance-Stimulation of the nonspecific defense against udder infections may improve control of mastitis.     

Development of a polymerase chain reaction to detect Vietnamese isolates of duck virus enteritis.

A polymerase chain reaction (PCR) method for the detection of duck virus enteritis (DVE) virus in tissues of infected and affected ducks, and in cell culture was developed. This required us to obtain specific nucleotide sequence information as we could not find any specific data about the genome of the virus. We found the assay to be highly effective in detecting the virus under experimental conditions and to be easily transferred to laboratories in Vietnam where it is being used in studies on the epidemiology of the disease. We have applied this simple and rapid diagnostic method to the detection of DVE isolates grown in cell culture and tissues from infected birds. The assay was also able to differentiate DVE from other avian herpesviruses, such as Marek's disease, infectious laryngotracheitis virus and goose herpesvirus.     

A vitamin e response in a young dog

Extract

This subject will be covered in three sections, first, a brief history of how the idea of using trained dogs to help the blind was conceived, then the present-day methods of training guide dogs, and, finally, how the blind person is trained with their guide dog to work together as a team.     

Detection of anticoagulant rodenticides (4-hydroxycoumarins) by thin-layer chromatography and reversed-phase high-performance liquid chromatography with fluorescence detection

The detection of 4-hydroxycoumarin rodenticides in poisoned domestic animals requires a highly sensitive method as tissue and serum levels of anticoagulants may be very low owing to rapid elimination, metabolism or post-mortem degradation. Thin-layer chromatography (TLC) and reversed-phase high-performance liquid chromatography (RP-HPLC) with fluorescence detection were used to identify the anticoagulants in spiked tissues and in suspicious samples. The analysis of ten suspicious samples highlighted the limitations of both methods. Only the three samples of baits were found positive by TLC whereas one of the five anticoagulants was detected in eight samples by RP-HPLC with fluorescence detection. Therefore, RP-HPLC with fluorescence detection proved to be the more sensitive method for detecting low levels of 4-hydroxycoumarins in blood serum, liver and ingesta, whereas TLC is usually sufficient for analysing baits.Abbreviations RP-HPLC reversed-phase high-performance liquid chromatography - TLC thin-layer chromatography     

Tumor necrosis factor-α and acute-phase proteins in early pregnant ewes after challenge with peptidoglycan-polysaccharide

Bacterial infection shortly after mating interferes with establishment of pregnancy. Injection of peptidoglycan-polysaccharide (PG-PS), a component of gram-positive bacteria, into sheep on day 5 after mating reduces pregnancy rate. Experiments were designed to evaluate the acute-phase response (APR) in ewes to injection of PG-PS on day 5 after mating (day 0). Catheters were inserted into the jugular and posterior vena cava on day 4. On day 5, ewes were challenged with saline or 30 μg/kg body weight (BW) PG-PS (Exp 1) or 60 μg/kg BW PG-PS (Exp 2). Blood samples were collected every 15 min for 6 h (Exp 1) and every 15 min for 2 h, hourly for 12 h, and at 24, 36, and 48 h (Exp 2). Body temperature and clinical signs of infection were monitored in Exp 2. Plasma was assayed for concentrations of a pro-inflammatory cytokine, tumor necrosis factor-α (TNF-α); 2 APR proteins, serum amyloid A (SAA) and haptoglobin (Hp); and progesterone (P₄). Ewes injected with 60 μg/kg BW PG-PS exhibited fever, vaginal discharge, loss of appetite, and lethargy. After challenge with either 30 μg/kg or 60 μg/kg BW PG-PS, TNF-α increased in the posterior vena cava. Concentrations of SAA and Hp in the jugular increased after challenge with 60 μg/kg BW PG-PS. Only half (5/10) of the ewes treated with 60 μg/kg BW PG-PS had ultrasonically visible embryos, and none of them had functional corpora lutea (CL) (<1 ng/mL of P₄) on day 21. On the other hand, 8/9 (88.9%) control ewes had visible embryos and all had functional CL on day 21. Using logistic regression, pregnancy on day 21 was predicted to depend on concentrations of TNF-α and Hp on day 5 and concentration of P₄ on day 14. In summary, injection of PG-PS on day 5 after mating resulted in fever; increased concentrations of TNF-α, Hp, and SAA on the day of and the day after the PG-PS challenge; and decreased concentrations of P₄ on days 14 and 21. These factors were related to failure to establish pregnancy.