In vitro susceptibility of Brachyspira hyodysenteriae to organic acids and essential oil components

The antibacterial potential of organic acids and essential oil components against Brachyspira hyodysenteriae, the causative pathogen of swine dysentery, was evaluated. Minimum inhibitory concentrations (MIC) of 15 compounds were determined at pH 7.2 and pH 6.0, using a broth microdilution assay. In addition, possible synergism was determined. MIC values for the three tested strains were similar. For organic acids, MIC values at pH 6.0 were lower than at pH 7.2. B. hyodysenteriae was most sensitive to cinnamaldehyde and lauric acid, with MIC values <1.5 mM. Most antibacterial effects of binary combinations were additive, however, for thymol and carvacrol, synergism could be observed. In vitro results demonstrate the antibacterial action of certain essential oil components and organic acids against B. hyodysenteriae.     

Context matters: the landscape matrix determines the population genetic structure of temperate forest herbs across Europe

Landscape Ecology - Plant populations in agricultural landscapes are mostly fragmented and their functional connectivity often depends on seed and pollen dispersal by animals. However, little is...     

Dynamics of <Emphasis Type="Italic">Mycoplasma hyopneumoniae</Emphasis> seroconversion and infection in pigs in the three main production systems

In this study, we investigated the dynamics of Mycoplasma hyopneumoniae infections in 66 pig farms, with different production systems (one-, two-, and three-site systems), and considered different risk factors. Serological assay was used to detect serum antibodies against M. hyopneumoniae and real time polymerase chain reaction (RT–PCR) was performed to detect M. hyopneumoniae DNA in tracheobronchial swabs. Results demonstrated that M. hyopneumoniae infection status was predominantly influenced by the age of the animals and the type of production system. Infection rates were higher in older animals and the prevalence was higher in the one- and two-site systems than in the three-site systems. Dynamics of infection by RT-PCR showed that earlier M. hyopneumoniae infection on one-site farms occurs earlier, while on two- and three-site farms occurs later but spreads faster, suggesting that contact between animals of different age favors the transmission.     

Use of a synthetic bone substitute to retard molariform tooth drift after maxillary tooth loss in ponies

OBJECTIVE: To evaluate the effect of alveolar bone substitute on post-extraction drift of maxillary cheek teeth in ponies. STUDY DESIGN: In vivo longitudinal experimental study. ANIMALS: Five ponies (5-7 years) with a healthy dentition. METHODS: Both maxillary 4th premolar teeth (Triadan 08) were surgically removed. One alveolus was filled with a biocompatible non-resorbable bone substitute (Bioplant 24), whereas the other healed by second intention. A polyvinylsiloxane plug and spring wire isolated the bone substitute from the oral environment. Pathologic changes to dentition and adjacent soft tissue were recorded. Tooth drift was calculated after 1 and 2 years. RESULTS: At 1 month, bone substitute material was incorporated into healthy tissue. Tooth drift was observed but differed significantly between control and treated sides at 2 years (P<.01). For both techniques, tooth drift differed significantly between years 1 and 2 (P<.001). Total drift in control arcades for year 1 was 10.69+/-2.12 mm and for year 2 was 9.08+/-0.87 mm, whereas for bone substitute arcades it was 9.90+/-1.60 mm for year 1 and 5.60+/-1.78 mm for year 2. CONCLUSIONS: Partial tooth replacement therapy after maxillary P4 extraction provided good healing in the immediate post-surgical phase. Alveolar filling with bone substitute material significantly slowed post-extraction tooth drift but did not stop it completely. Clinical Relevance- Important changes occur in equine dentition after maxillary cheek teeth removal. Further longer term observations are needed to fully validate study findings.     

Quantification and evaluation of antimicrobial drug use in group treatments for fattening pigs in Belgium

To control the emergence of antimicrobial resistance, knowledge of antimicrobial drug consumption is essential. Because consumption data are not available in Belgium, a study was conducted between March and October 2003 to investigate the antimicrobial drug consumption in pigs, using the treatment incidence based on the animal daily dose pig (ADDpig), the treatment incidence based on the used daily dose pig (UDDpig) (number of ADDpig or UDDpig/1000 pigs at risk/day), and the ratio UDDpig/ADDpig.

The sampling frame consisted of 821 pig herds that (a) used a closed or semi-closed production system, (b) were located in the most dense pig areas of Belgium, and (c) had at least 150 sows and 600 fattening pigs each. Of 50 randomly selected herds, all group treatments with antimicrobial drugs, applied to fattening pigs that were within 2 weeks of slaughter (median age 187 days), were collected retrospectively.

The treatment incidence based on ADDpig for all oral and injectable antimicrobial drugs was 178.1 per 1000 pigs at risk per day. The treatment incidence based on UDDpig shows that in reality fewer pigs were treated, namely 170.3 per 1000 pigs at risk per day. Proportionally, the most often applied oral antimicrobial drugs were: doxycycline, amoxicillin, combination trimethoprim-sulphonamides and polymyxin E. The most often applied injectable antimicrobial drugs were long-acting amoxicillin and ceftiofur. The distribution of the UDDpig/ADDpig ratio per antimicrobial drug shows that 50–75% of the oral formulations were underdosed. Injectable formulations were almost always overdosed (>90%).     

A longitudinal study of the diversity and dynamics of Mycoplasma hyopneumoniae infections in pig herds

A longitudinal study was carried out to investigate the diversity and persistence of Mycoplasma hyopneumoniae (M. hyopneumoniae) strains in four infected pig herds. In each herd, 20 pigs were randomly selected and blood and/or bronchoalveolar lavage (BAL) fluid was collected at 6, 10, 14 and 26 weeks of age. In the BAL fluid, quantitative PCR and MLVA (multiple-locus variable number of tandem repeats (VNTR) analysis) testing were performed for detection and typing of M. hyopneumoniae strains, respectively. At 26 weeks of age, the prevalence and severity of lung lesions were recorded at slaughter (minimum 50 pigs belonging to the same batch as the investigated pigs). The percentage of pigs testing positive on qPCR increased from 35% at 6 weeks to 96% at 26 weeks of age. With MLVA testing, positive pigs were found from 14 weeks onwards. Within each herd, only one distinct strain was detected, although clonal variants were identified in two herds. In three of the herds, the strain remained present until slaughter age. The percentage of pigs with Mycoplasma-like lesions ranged from 38% to 98%, and the average pneumonia score ranged from 1.7 to 11.9, respectively. The present field study documented that within a herd, mainly one distinct M. hyopneumoniae strain was present that persisted in the same animals for at least 12 weeks. This implies that the immune response of the animals following infection is not able to rapidly clear the infection from the respiratory tract.     

Discrepancies between the isolation of Salmonella from mesenteric lymph nodes and the results of serological screening in slaughter pigs

Most Salmonella control programmes are based on serological testing in the slaughterhouse. However, from a point of view of carcass contamination, it is rather the presence of Salmonella spp. in the animal at the time of slaughter that is important. The aim of this cross-sectional study was to investigate the possible discrepancies between the isolation of Salmonella spp. in the mesenteric lymph nodes and the results of serological screening. In total, 1821 fattening pigs originating from 60 Belgian farrow-to-finish herds were sampled in the slaughterhouse. The serum samples were analysed using an indirect mix-ELISA for the presence of Salmonella antibodies and evaluated at 3 cut-off values namely 10, 20, and 40% Optical Density (OD). All mesenteric lymph node samples were submitted to qualitative Salmonella isolation and a representative number of isolates was serotyped. From each herd, 30 animals were screened both serologically and bacteriologically and the herd was considered as positive when at least one sample was positive. At the herd level, 83.6% (cut-off OD 40%) to 100.0% (cut-off OD 10%) of the herds from which Salmonella had been isolated were evaluated as seropositive. At the individual level, only 34.5% (cut-off OD 40%) to 82.8% (cut-off OD 10%) of the animals from which Salmonella had been isolated were seropositive. Overall, a weak agreement was found between bacteriology and serology for Salmonella diagnosis. If pig herds are categorised using serological tests in the slaughterhouse, one should be aware of the fact that slaughter pigs can still harbour Salmonella spp. in the mesenteric lymph nodes, without being detected in serological tests. The cut-off value used to evaluate a sample as serologically positive and the number of samples per herd are of major importance to classify herds correctly in order to protect human health.     

妥曲珠利对等孢球虫病亚临床感染猪群中仔猪生长的影响

由球虫属猪等孢子球虫引起的仔猪等孢子球虫病,被认为是一个会对养猪业产生明显有害影响的疾病。虽然此病不会导致猪的高死亡率,但会降低养猪者的生产率,从而影响其经济报酬(Torres,2004)。