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 bird's 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.

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.

Two identical experiments were carried out to study the effects of four xylanases from bacterial or fungal origin supplemented to a wheat-based diet, on growth performance of broiler chickens and nutrient digestibilities. Experimental treatments consisted of a control basal diet containing 600 g kg-1 wheat (C), and the basal diet supplemented with 0.1 g kg-1 Grindazyme G from Aspergillus niger (G), 0.1 g kg-1 Belfeed B1100MP from Bacillus subtilis (B), 0.1 g kg-1 Roxazyme G from Trichoderma viride (R), or 0.0125 g kg-1 of a xylanase from Aspergillus aculeatus (A). Each experimental diet was given to four groups of six chickens each. Growth performance and feed conversion ratio (FCR) were recorded weekly, from 7 to 21 d of age. In the second experiment, a digestion balance trial was performed from 27 to 31 d of age to evaluate the nitrogen-corrected apparent metabolizable energy (AMEn) and the digestibilities of nitrogen, crude fat, starch and crude fibre. From 7 to 21 d of age, xylanase supplementation led to increased final body weight and daily weight gain, by 3.7 and 4.5 % (P < 0.05), respectively, without significant difference according to the xylanase origin. Xylanase supplementation significantly increased the AMEn (+2.6 %), and the digestibilities of crude fibre (+58.9 %) and nitrogen (+1.6 %). Increase in AMEn as well as in crude fat and starch digestibilities were significantly different according to the xylanase, but were not dependent on fungal or bacterial origin. In conclusion, the microbial origin of xylanases supplemented to wheat-based diets influenced neither the performance of broiler chickens nor the improvement in nutrient digestibilities.Key words: Broiler, growth performance, nutrient digestibility, wheat, xylanase

Salmonella is a major causative organism of gastroenteritis in humans worldwide, and most cases are caused by the consumption of raw or undercooked poultry products. In response to public concern, many countries have introduced survey and control programmes for Salmonella in poultry. However, it remains an economic burden in many areas, and there are emerging risks associated with new serovars. In this chapter, we describe the invasion and transmission mechanisms of Salmonella, review the currently available detection methods and then provide a detailed overview of the strategies available for controlling Salmonella in poultry, with a particular focus on those employed before the meat is harvested.