Evaluation of the Salmonella surveillance program in Belgian pig farms

Since July 2007, Belgium has implemented a national surveillance and control program for Salmonella in pigs. Pig farms are designated as Salmonella high risk farms based on serological profiles and are obliged to subsequently take part in a Salmonella specific action plan (SSAP). The SSAP was evaluated and potential risk factors for the persistence of Salmonella on the farm were investigated. First, the Kaplan-Meier method was used in order to study the period during which a farm maintains a Salmonella high risk status. Farms recovered more slowly from their high risk status before the SSAP was implemented compared to after the program was implemented (p<0.001). However, results showed that 29% of the farms were withdrawn from the program possibly only because of sampling error. The program should thus be adapted to accommodate for this. Secondly, the influence of several risk factors (type of farm, season of entrance into the SSAP, size of farm and farm density of the municipality) on the time to withdrawal from the high risk status was evaluated using univariable methods and a Cox multiple regression model for survival data. A statistically significant association was identified between the type of farm and the time to withdrawal from the high risk status. At any point in time after the onset of the SSAP, withdrawals from the high risk status occurred at a 39% and 28% higher rate in mixed (p=0.01) and fattening farms (p=0.05), respectively, compared to closed farms. The risk attributed to closed pig farms is related to the presence of sows in this particular type of structure, which underlines the importance of implementing control measures in this category of animals.     

The use of lingual venous blood to determine the acid‐base and blood‐gas status of dogs under anesthesia

ObjectiveTo assess the suitability of lingual venous blood (LBG) as an alternative to arterial blood (ABG) samples in determining acid–base balance and blood–gas status in dogs anesthetized for elective procedures and with medetomidine and isoflurane administration under experimental conditions.Study designProspective, randomized clinical and experimental study.AnimalsClinical population of 18 ASA I/II dogs for elective surgery and five healthy Beagles (3 females and 2 males) for the experimental study.MethodsBlood sampling was simultaneously performed at dorsal pedal arterial and lingual venous sites, generating paired data. Two paired samples were collected from each dog in the clinical part and four from each dog in the experimental part (two during isoflurane anesthesia and two during isoflurane plus medetomidine). A modified Bland and Altman method was used to examine data from the clinical part and the experimental data were subjected to a paired sign's test following transformation where appropriate.ResultsThe pH of LBG overestimated ABG, with limits of agreement of (?0.01, 0.02). The partial pressure of carbon dioxide (PCO₂) of LBG overestimated ABG by 0.6 mmHg [0.1 kPa], with limits of agreement of (?3.5, 4.6) mmHg [?0.5, 0.6 kPa]. The partial pressure of oxygen (PO₂) of LBG underestimated ABG by 86.3 mmHg [?11.5 kPa], with limits of agreement of (?199.8, 27.3) mmHg [?26.6, 3.6 kPa]. During medetomidine administration values for PO₂ (p = 0.03) and lactate (p = 0.03) were lower for LBG when compared with ABG. The LBG value of PO₂ was lower (p = 0.03) during medetomidine and isoflurane administration versus isoflurane alone.Conclusions and clinical relevanceThe pH and PCO₂ of LBG samples provide clinically acceptable substitutes of ABG samples in the dog population studied. The wider limits of agreement for PO₂ render it less reliable as a substitute for ABG. The difference in PO₂ identified between LBG and ABG during medetomidine administration may not preclude the use of LBG as substitutes for ABG samples.     

Comparative study of plasma leptin concentration between solid ruminal and liquid abomasal feeding in weaned adult sheep

This experiment was conducted to investigate the difference between ruminal (solid feed, SF) and abomasal (liquid feed, LF) feeding on the plasma leptin concentration in sheep. The experiment consisted of 2 weeks to adapt the animals to SF, 4 weeks of feeding on SF, 2 weeks adaptation to LF, 8 weeks of feeding on LF, 2 weeks of adaptation to SF, and 4 weeks of feeding on SF. The LF directory flowed into the abomasums of sheep by bottle feeding. Plasma leptin concentration before morning feeding was almost constant in the SF periods, whereas it showed between‐day variations when measured during the LF periods. Mean plasma leptin levels were higher for LF (7.77 ± 0.76 ng/mL; mean ± SE) than for SF periods (3.95 ± 0.16 ng/mL; mean ± SE). Although plasma leptin concentration did not show any change after feeding in the SF and LF periods, plasma insulin and glucose levels increased within 15 min after liquid abomasal feeding, but not after solid ruminal feeding. The high plasma leptin concentration during the LF periods in weaned sheep could be due to change of digestible energy intake and changes in plasma insulin and glucose levels accompanying the changes in digestive processes and nutrient supply.     

Early hepatic immune response in rats infected with Fasciola hepatica

We investigated the phenotype of the T cells (CD4+ and CD8+) that produced Th1 (IFN-gamma) and Th2 cytokines (IL-4 and IL-10) during the firsttwo weeks of experimental fasciolosis in rats. We also followed the kinetics of the cytokine and proliferative responses of hepatic mononuclear cells (HMNC) over the same period. We found that HMNC were more numerous in the infected animals than in the controls. The percentage of CD4+ cells increased significantly after infection, whereas the percentage of CD8+ cells did not change. Moreover, the frequency of the cells producing (CP) cytokine changed after infection. The frequency of CP IFN-gamma on 7 days postinfection (pi) was similar to that in control animals. However, the frequency of CP IFN-gamma was clearly lower on day 14 pi, whereas the frequency of CP IL-4 and CP IL-10 had increased. The CP IL-10-were mostly CD4+. Mitogenic stimulation (phorbol myristate acetate/ionomycin) of HMNC led to an increase in the amounts of the Th2 cytokines in the supernatant on days 7 and 14 pi, with the increase more pronounced on day 14. In contrast, IFN-gamma levels also increased by day 7 pi but then decreased to below control levels by day 14. In addition, HMNC proliferation in response to mitogen followed a similar pattern to IFN-gamma production. These findings suggested that, during the first 2 weeks of infection, F hepatica induced a transient ThO cytokine profile followed by downregulation of the cellular response and the induction of a Th2 cytokine profile.     

In vitro digestibility of α-casozepine, a benzodiazepine-like peptide from bovine casein, and biological activity of its main proteolytic fragment

α-Casozepine is a peptide, corresponding to the sequence 91-100 of the bovine α(s1)-casein, displaying anxiolytic activity in the rat. The α(s1)-casein tryptic hydrolysate containing this peptide decreases stress effects after oral administration in various species including man. Therefore, the stability of this peptide toward gastric and pancreatic proteases has been assessed by using pepsin, chymotrypsin/trypsin, Corolase PP, pepsin followed by chymotrypsin/trypsin or pepsin followed by Corolase PP. α-Casozepine was slowly degraded by chymotrypsin, much more sensitive to pepsin and Corolase PP but not completely destroyed after 4 h kinetics. The bonds in the region 91 to 95 of the α-casozepine were totally resistant to hydrolysis by all studied proteases. Surprisingly, a fragment, corresponding to the sequence 91-97 and found in all the hydrolysis media in significant amount, possessed an anxiolytic activity in three behavioral tests measuring this parameter. This peptide could participate in the in vivo activity of α-casozepine.     

Sexual and somatic hybridization in the genus Lactuca

Summary Various genes for disease resistance identified in wild Lactuca are difficult, even impossible to exploit in lettuce breeding, due to sexual incompatibility between L. sativa and wild Lactuca sp. We adapted two cellular biology techniques to overcome these interspecific barriers: in vitro embryo rescue and protoplast fusion. In vitro rescue of immature embryos was used successfully for sexual hybridization between L. sativa and L. virosa. Vigorous hybrid plants were produced between L. sativa and seven accessions of L. virosa. Protoplast fusion permitted the regeneration of somatic hybrids between L. sativa and either L. tatarica or L. perennis. Hybrids between L. sativa and L. tatarica were backcrossed to L. sativa.     

The Schmallenberg virus epidemic in Europe—2011–2013

During the Schmallenberg virus (SBV) epidemic, the European Food Safety Authority (EFSA) collected data on SBV occurrence across Europe in order to provide an assessment of spread and impact. By May 2013, twenty-nine countries were reporting to EFSA and twenty-two countries had reported cases of SBV. The total number of SBV herds reported was 13,846 and the number of SBV laboratory confirmed herds was 8730. The surveillance activities were based on the detection of SBV clinical cases (either adults or newborns). Malformation in newborns was the most commonly reported clinical sign of SBV-infection. All countries were able to provide the date when the first suspicion of SBV in the herd was reported and nineteen could report the location of the herd at a regional level. This allowed the spread of SBV in Europe to be measured both temporally and spatially. The number of SBV confirmed herds started to increase in December 2011 and two peaks were observed in 2012 (February and May). Confirmed herds continued to be reported in 2012 and into 2013. An increase during winter 2012 and spring 2013 was again observed, but the number of confirmed herds was lower than in the previous year. SBV spread rapidly throughout Europe from the initial area of detection. SBV was detected above the latitude of 60° North, which exceeds the northern expansion observed during the bluetongue virus serotype 8 epidemic in 2006–2009. The impact of SBV was calculated as ratio of the number of herds with at least one malformed SBV positive foetus and the total number of herds in this region. The 75th percentile of the malformations ratio in the various affected countries for the whole reporting period was below 1% and 3% for cattle and sheep herds, respectively. International data collection on emerging diseases represents a challenge as the nature of available data, data quality and the proportion of reported cases may vary widely between affected countries. Surveillance activities on emerging animal diseases are often structured only for case detection making the estimation of infection/diseases prevalence and the investigation of risk factors difficult. The impact of the disease must be determined to allow risk managers to take appropriate decisions. Simple within-herd impact indicators suitable for emerging disease outbreaks should be defined that could be measured as part of routine animal health surveillance programmes and allow for rapid and reliable impact assessment of emerging animal health diseases.     

Shrinkage variation in Japanese larch (Larix kaempferi, [Lamb.]Carr.) progenies/provenances trials in Eastern Canada

Twelve-year-old Japanese larch (Larix kaempferi [Lamb.]Carr.) trees of 20 different progenies and/or provenances were sampled at one site in the Mauricie region of Quebec. Two standard samples were obtained at breast height and closer to the bark from each tree. Partial and total radial, tangential, and volumetric shrinkages, and tangential/radial (T/R) shrinkage ratios were assessed. All of these variables were significantly affected by the progeny/provenance. Drying defects are one of the main reasons for downgrading larch lumber; thus, T/R shrinkage ratio was considered for the selection of progenies/provenances for lumber production purposes. Lowest partial and total T/R shrinkage ratios were obtained with progenies/provenances 8964, 8904, 8962, 8957, 8907, 8927, 7283, and 7795. Among them, lowest partial and total tangential, radial, and volumetric shrinkages were found in progenies/provenances 8964, 8962, and 8907 as well. Other physico-chemical (mechanical properties, density, extractive content) and silvicultural (growth rate) attributes should also be taken into consideration for an adequate selection of progenies/provenances according to the specific final utilization.     

Farmers' knowledge and perceptions of termites as pests of yam (Dioscorea spp.) in Central Benin

Destruction of yam (Dioscorea spp.) tubers by termites is a major constraint to yam production in Central Benin. To obtain the basic information for the development of appropriate strategies of termites management in yam, a structured questionnaire was used to interview 142 farmers about their knowledge of termite species of yam, susceptibility of yam landraces, and management practices in 14 villages through the study area. A total of 45 vernaculars names of termites were recorded corresponding to 10 species. All the names given to termite species had a signification, mainly related to morphological aspects, type of damage, and termite caste. Eleven features were used by farmers to identify yam termites. The infestation of yam fields mostly occurred from October to April with Amitermes evuncifer and Trinevitermes oeconomus being the most damaging termite species. Overall, eight factors were identified by farmers as favouring the proliferation of termites in yam fields with drought being the most frequently reported factor. Farmers identified 11 yam landraces that were highly susceptible to termites attack, while 12 yam landraces were listed as resistant. Application of chemicals was the most commonly reported control method, followed by destruction of termite nest, and application of botanical extracts. According to farmers, the high multiplication rate of termites is the most important constraint in managing the issue of termites in yam.     

Fractal dimension estimates of a fragmented landscape: sources of variability

Although often seen as a scale-independent measure, we show that the fractal dimension of the forest cover of the Cazaville Region changes with spatial scale. Sources of variability in the estimation of fractal dimensions are multiple. First, the measured phenomenon does not always show the properties of a pure fractal for all scales, but rather exhibits local self-similarity within certain scale ranges. Moreover, some sampling components such as area of sampling unit, the use of a transect in the estimation of the variability of a plane, the location, and the orientation of a transect all affect, to different degrees, the estimation of the fractal dimension. This paper assesses the relative importance of these components in the estimation of the fractal dimension of the spatial distribution of woodlots in a fragmented landscape. Results show that different sources of variability should be considered when comparing fractal dimensions from different studies or regions.