André Thewis

Salmonella in Chicken: Current and Developing Strategies To Reduce Contamination at Farm Level

Salmonella is a human pathogen that frequently infects poultry flocks. Consumption of raw or undercooked contaminated poultry products can induce acute gastroenteritis in humans. Faced with the public health concerns associated with salmonellosis, the European Union has established a European regulation forcing member states to implement control programs aimed at reducing Salmonella prevalence in poultry production, especially at the primary production level. The purpose of the present review article is to summarize the current research and to suggest future developments in the area of Salmonella control in poultry, which may be of value to the industry in the coming years. The review will focus especially on preventive strategies that have been developed and that aim at reducing the incidence of Salmonella colonization in broiler chickens at the farm level. In addition to the usual preventive hygienic measures, other strategies have been investigated, such as feed and drinking water acidification with organic acids and immune strategies based on passive and active immunity. Modification of the diet by changing ingredients and nutrient composition with the intent of reducing a birds susceptibility to Salmonella infection also has been examined. Because in ovo feeding accelerates small intestine development and enhances epithelial cell function, this approach could be an efficient tool for controlling enteric pathogens. Feed additives such as antibiotics, prebiotics, probiotics, and synbiotics that modify the intestinal microflora are part of another field of investigation, and their success depends on the additive used. Other control methods such as the use of chlorate products and bacteriophages also are under study.

Hyperspectral Imaging Applications in Agriculture and Agro-Food Product Quality and Safety Control: A Review

Abstract In this review, various applications of near-infrared hyperspectral imaging (NIR-HSI) in agriculture and in the quality control of agro-food products are presented. NIR-HSI is an emerging technique that combines classical NIR spectroscopy and imaging techniques in order to simultaneously obtain spectral and spatial information from a field or a sample. The technique is nondestructive, nonpolluting, fast, and relatively inexpensive per analysis. Currently, its applications in agriculture include vegetation mapping, crop disease, stress and yield detection, component identification in plants, and detection of impurities. There is growing interest in HSI for safety and quality assessments of agro-food products. The applications have been classified from the level of satellite images to the macroscopic or molecular level.

Influence of extrusion on ruminal and intestinal disappearance in sacco of pea (Pisum sativum) proteins and starch

Walhain, P., Foucarl, M. and Th&vis, A., 1992. Influence of extrusion on ruminal and intestinal disappearance in sacco of pea (Pisum sarivurn) proteins and starch. Anim. Feed&i. Techno/., 38: 4355. Two Holstein steers fitted with permanent ruminal cannulae and three Belgian Blue bulls equipped with permanent ruminal and duodenal cannulae were used in two experiments to study ruminal protein and intestinal digestibility in sacco of extruded peas (Pisurn sarivurn). Samples of crude peas ( 5 g) and peas extruded at 140, 180 and 220°C were weighed in large nylon bags and incubated in the rumen for 2,4,8, I6 and 24 h. Samples of peas ( I g) extruded al 140°C soya-bean meal and extruded soya-bean seeds were weighed in small bags, incubaled in the rumen for 16 h and then inserted into the duodenum. Results were interpreted by titling disappearance data of dry matter and nitrogen in the mmen by an iterative least squares procedure while intestinal disappearance was calculated from the amounts of inilial and residual nitrogen in the bags al the duodenal and faecal sites. Extrusion of peas &id not significantly affect dry matter effective degradability, but dramatically reduced crude protein effeclive degradability (88.3% vs. 65.59al an outflow rafe of0.06 h-l). lo addition, extrusion greatly increased the rate of disappearance of starch in the rumen. The small mechanically released crude protein fractions of the feeds did not lead lo an important overestimation of their degradability nor did it affect their classification, but reflected the high protein solubility ofthe crude peas. In our experimental conditions, it appeared unnecessary to increase extrusion temperature above 140°C. Above this temperature, protein protection was not significantly improved. The low values observed for residual nitrogen of mobile nylon bags (0.45 g kg-’ DM) and high nitrogen pepsin solubilily (95.8%) of peas extruded al 14O’C demonstrati itd extrusion had little or even no aegalive effect on intestinal digestibility. Extrusion failed lo improve significantly the essential amino acids profile of extruded peas in the undegradable ruminal fraction but seemed to increase the essential amino acids concentration of residual extruded soya-bean seeds.

Cell dynamics and immune response to BLV infection: a unifying model

Bovine Leukemia virus (BLV) is the natural etiological agent of a lymphoproliferative disease in cattle. BLV can also be transmitted experimentally to a related ruminant species, sheep, in which the pathogenesis is more acute. Although both susceptible species develop a strong anti-viral immune response, the virus persists indefinitely throughout life, apparently at a transcriptionally silent stage, at least in a proportion of infected cells. Soon after infection, these humoral and cytotoxic activities very efficiently abolish the viral replicative cycle, permitting only mitotic expansion of provirus-carrying cells. Short term cultures of these infected cells initially indicated that viral expression protects against spontaneous apoptosis, suggesting that leukemia is a process of accumulation of long-lived cells. This conclusion was recently reconsidered following in vivo dynamic studies based on perfusions of nucleoside (bromodeoxyuridine) or fluorescent protein markers (CFSE). In sheep, the turnover rate of infected cells is increased, suggesting that a permanent clearance process is exerted by the immune system. Lymphocyte trafficking from and to the secondary lymphoid organs is a key component in the maintenance of cell homeostasis. The net outcome of the immune selective pressure is that only cells in which the virus is transcriptionally silenced survive and accumulate, ultimately leading to lymphocytosis. Activation of viral and/or cellular expression in this silent reservoir with deacetylase inhibitors causes the collapse of the proviral loads. In other words, modulation of viral expression appears to be curative in lymphocytic sheep, an approach that might also be efficient in patients infected with the related Human T-lymphotropic virus type 1. In summary, a dynamic interplay between BLV and the host immune response modulates a complex equilibrium between (i) viral expression driving (or) favoring proliferation and (ii) viral silencing preventing apoptosis. As conclusion, we propose a hypothetical model unifying all these mechanisms.

Trypsin inhibitors in peas: varietal effect and influence on digestibility of crude protein by growing pigs.

The trypsin inhibitor activity (TIA) of 33 European spring pea varieties was determined. The TIA ofthe varieties Maro, Progreta, Consort and Radley ranged from 6.1 to 8.4 trypsin inhibited units per mg dry matter (TIU mg−1 DM), whereas all the other varieties had ⩽ 3 TIU mg−1 DM. Maro, Progreta and Consort are British varieties of the ‘marrowfat’ type which have classically a high activity. The French winter varieties had a high TIA (mean, 9.1 TIU mg−1 DM), but the varieties arising from a cross between a winter and a spring variety, such as Frilene, Amac, Laser and Santon, had a lower activity. The results were compared with those obtained for six other legume seeds: faba beans, vetches, lentils, pigeonpeas, chickpeas and haricot beans. Finally, a comparison of the TIA of samples of the variety Finale originating from different fields showed that growth conditions influenced the pea TIA. The apparent digestibility of the main constituents of two spring pea varieties (Finale, 2.35 and Progreta, 7.48 TIU mg−1 DM) was determined, by the difference method, using growing pigs with diets consisting of 40% peas. The apparent digestibility of organic matter, crude fibre and crude energy was similar for the two varieties, whereas the apparent digestibility of the crude protein of Progreta was significantly lower (P < 0.05) than that of Finale. The influence of trypsin inhibitors on the apparent digestibility of crude protein was discussed and all other hypotheses which could explain this difference were considered.

Efficiency of a Lactobacillus plantarum-xylanase combination on growth performances, microflora populations, and nutrient digestibilities of broilers infected with Salmonella Typhimurium

Three experiments were performed to assess the ability of a Lactobacillus plantarum probiotic combined with a xylanase to reduce the effects of Salmonella Typhimurium infection in broiler chickens from 1 to 30 or 42 d of age. Chicks were challenged at 3 d of age with 10(8) or 10(5) cfu Salmonella Typhimurium/chick. Four diets were studied: a wheat-based diet (C+) supplemented with 0.1 g/kg of xylanase (E) or 10(6) cfu/g of L. plantarum (P), or both (PE). Uninfected chicks fed the C diet were used as negative control (C-). Six or 8 chicks were housed per cage with 9 cages/treatment. Growth performance and feed conversion ratio (FCR) were recorded weekly. In experiment 1, bacterial enumeration in ceca was achieved using the fluorescent in situ hybridization technique. Salmonella enumeration was realized in excreta by microbiological cultures (experiments 2 and 3). Nutrient digestibilities and AME(n) were determined in experiment 3 from d 35 to 39. Infection with Salmonella Typhimurium led to a significant decrease in the daily weight gain (DWG) by 23.6 to 32.8%, whereas FCR was increased by 1.0 to 19.7%. Chickens fed the PE diet showed significantly improved performance in comparison with C+ birds (DWG: +12.5% in experiment 1; FCR: -2.1 to 8.6%), and in comparison with the P and E treatments (DWG: +6.3 to 8.3% in experiment 1; FCR: -2.7 to 6.4%). In experiment 3, the FCR was significantly improved by 3% with the PE diet in comparison with C- chickens. The PE combination tended to restore a microflora similar to that of uninfected broilers, whereas the P and E diets had less of an effect on the profile of bacterial communities. At slaughter age, Salmonella contamination was reduced by 2.00 and 1.85 log colony-forming units for the E and PE treatment, respectively. The PE diet significantly reduced the crude fat digestibility by 9.2%, in comparison with the C+ chickens. These results suggest that the combination between L. plantarum and a xylanase as feed additive could be effective for reduction of the detrimental effect after Salmonella Typhimurium infection of broilers.

Effect of oral and parenteral N nutrition vs N-free nutrition on the endogenous amino acid flow at the ileum of the pig

Two methods were tested for suppressing the depressive effect of N-free diets on the digestive secretions in pigs : the blood perfusion of amino acids (AA) or the peptide alimentation method. In the latter, enzymically hydrolysed casein (EHC), composed of oligopeptides and free AA, was used as the source of nitrogen. The unabsorbed dietary N molecules were discarded from the ileal digesta by ultrafiltration or gel filtration, assuming that the endogenous fraction did not contain significant amounts of small molecules. The AA supply by blood perfusion had no effect on the ileal endogenous AA losses (8.0 g AA kg -1 DM intake) in growing pigs (±50 kg), compared with the N-free diet alone (8.3 g), whereas the EHC supplementation significantly increased them (18.0 g). The increase was due to both endogenous and dietary N. The presence of unabsorbed dietary AA in the ileal digesta was confirmed by the AA profile of the soluble molecules with a very low molecular mass ( < 3 kDa), which was close to that of EHC. Both ultrafiltration (cut-offs of 3 or 10 kDa) and gel filtration methods, utilised to discard the remaining dietary molecules, also eliminated a significant proportion of endogenous AA.

Effects of feed supplementation with specific hen egg yolk antibody (immunoglobin Y) on Salmonella species cecal colonization and growth performances of challenged broiler chickens

Anti-Salmonella spp. egg yolk antibodies (IgY) simultaneously directed against Salmonella Enteritidis and Salmonella Typhimurium were tested to determine if their inclusion in feed decreased Salmonella spp. cecal colonization in experimentally infected broiler chickens. Egg yolk powder (EYP) was obtained by freeze-drying egg yolks containing anti-Salmonella spp. Immunoglobin Y was included in feed at 5 levels of concentration (0 to 5%). Feeds were formulated to similar nutrient levels and provided for ad libitum intake from d 1 to 28. Three days after initiation of feed treatments (d 4), chickens were co-challenged with equal numbers of Salmonella Enteritidis and Salmonella Typhimurium (2x10(6) cfu/bird). Cecal samples were recovered weekly over the experimental period (d 7 to 28) to enumerate Salmonella spp. The effect of anti-Salmonella spp. IgY feed supplementation on growth performance of infected chickens was also evaluated during the same period. In comparison with the positive control treatment (PC), treatments involving EYP (T1, T2, T3, T4, and T5), whether containing anti-Salmonella spp. IgY or not, significantly improved (P<0.05) the growth performance of challenged chickens, but without reaching the performance levels of nonchallenged chickens (NC1 and NC2). However, no link can be established between the enhancement in growth performance of challenged birds and their contamination levels by Salmonella because in-feed incorporation of EYP had no significant effect on cecal colonization by Salmonella. Furthermore, the comparison of the 5 anti-Salmonella spp. IgY concentration levels in feed did not reveal any anti-Salmonella spp. IgY concentration effect on growth performance and Salmonella cecal colonization. These results suggest that anti-Salmonella spp. IgY would undergo denaturation and degradation after their passage through the animal gastrointestinal tract and reveal that components of EYP other than specific antibodies have a beneficial effect on growth performance.

Salmonella Typhimurium oral challenge model in mature broilers: Bacteriological, immunological, and growth performance aspects

In this study, Salmonella enterica serovar Typhimurium challenge models were tested to identify the best conditions under which to perform the experimental infection of 3-wk-old broilers. Such a model would be useful to study the efficiency of therapeutic treatments that could take place at the end of the grow-out period. Salmonella-free chicks were obtained from a breeder flock vaccinated with Salmonella. Intestinal maternal immunity was monitored by ELISA analyses at 2, 9, and 16 d of age. Data indicated that protection of maternal origin was not maintained over time and was drastically reduced at 9 d of age (P < 0.01). At 21 d of age, chickens were orally inoculated with Salmonella Typhimurium. The effects of the oral challenge dose (0, 3 × 10(3), 3 × 10(6), and 3 × 10(9) cfu/bird) and vancomycin pretreatment (no administration or 25 mg/bird) on intestinal immune responses, growth performance, and Salmonella colonization of chickens were investigated. After infection, the mucosal immune response was rapid, with increased (P < 0.01) anti-Salmonella Typhimurium IgA titers measured at 8 d postinfection in intestinal contents. A linear relationship (P < 0.05) existed between specific IgA levels in intestinal and cecal contents and the challenge dose inoculated. None of the challenge protocols caused mortality or clinical symptoms after infection. Nevertheless, the experimental infection induced a significant deterioration of growth performance. The pretreatment with 25 mg of vancomycin at 3 h before Salmonella inoculation was able to establish stable infection rates among the population of 3-wk-old infected chickens. Nevertheless, Salmonella shedding was not stable over the rearing period, and the bacteria seemed to be naturally eliminated from most birds at 22 d postinfection. This natural clearance of the gut, which was related, at least in part, to the intestinal immune response, should limit the usability of the created mature challenge model within 1 to 2 wk after inoculation.

Production of Hen Egg Yolk Immunoglobulins Simultaneously Directed Against Salmonella Enteritidis and Salmonella Typhimurium in the Same Egg Yolk

Abstract The present study was an attempt to raise hen egg yolk Ig (IgY) simultaneously directed against Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST) in the same egg yolk. The immunopotentiating effect of 2 different adjuvants—Freund’s adjuvants (FA) and immunostimulating complexes matrix (IM)—on antibody response was also evaluated. Bacterial outer membrane proteins (OMP) were selected as target antigens. The ISA Brown hens, specific-Salmonella spp.-free status, divided into 6 groups were intramuscularly injected with a mono-compound antigen preparation: SE-OMP (treatment SE-FA or SE-IM) or ST-OMP (treatment ST-FA or ST-IM), or a combined antigen preparation: ½ SE-OMP and ½ STOMP (treatment SEST-FA or SEST-IM). Titers of antibodies in yolk were evaluated biweekly with ELISA. There was no antigen × adjuvant interaction on antibody titers. Anti-SE IgY titers in hens that received treatment SEST-FA or SEST-IM were statistically similar (P > 0.05) as compared with those obtained from hens immunized with treatment SE-FA or SE-IM. Anti-ST IgY titers in hens immunized with treatment SEST-FA or SEST-IM were slightly lower than those of hens that received treatment ST-FA or ST-IM. The cross-reactivity of anti-SE IgY, induced by treatment SE-FA or SE-IM, with ST-OMP antigen and that of anti-ST IgY, induced by ST-FA or ST-IM, with SE-OMP antigen were arbitrarily assessed on d 43 and 155 by ELISA. The average cross-reactivity of anti-SE IgY with ST-OMP antigen was 71.7%. The average cross-reactivity of anti-ST IgY with SE-OMP antigen was 78.8%. In FA groups, antibody titers were found higher (P < 0.05) than those in IM groups. Furthermore, no extensive lesions or clinical abnormalities were detected in hens injected with FA. These findings showed the opportunity to raise IgY antibody against 2 Salmonella serovars in the same yolk and that FA was more efficient than IM in mediating antibody response.