The addition of charcoals to broiler diets did not alter the recovery of Salmonella Typhimurium during grow-out.

Two experiments evaluated prebiotics added to feed on the recovery of Salmonella in broilers during grow-out and processing. In Experiment 1, "seeder" chicks were inoculated with Salmonella Typhimurium and placed with penmates. Treatments were: basal control diet, added 0.3% bamboo charcoal, 0.6% bamboo charcoal, or 0.12% Aromabiotic (medium chain fatty acids). The ceca from seeders and penmates were sampled to confirm Salmonella colonization at 3, 4, and 6 wk, and pen litter was sampled weekly. At 3 wk, charcoal fed chicks had significantly lower cecal recovery (37% lower) of Salmonella via direct plating but no differences at wk 4 or 6. At 6 wk, broilers fed Aromabiotic had no recovery of Salmonella from ceca with direct plating and significantly, 18%, lower recovery with enrichment. In Experiment 2, the treatments were: basal control diet, added 0.3% bamboo charcoal, 0.3% activated bamboo charcoal, or 0.3% pine charcoal. At placement, 2 seeders were challenged with Salmonella and commingled with penmates and ceca sampled at 1 and 2 wk, and ceca from 5 penmates/pen at 3 to 6 wk. Weekly, the pH of the crop and duodenum was measured from 1 penmate/pen and the litter surface sampled. At the end of grow-out broilers were processed. Results showed that penmates had colonized at 1 and 2 wk. Cecal Salmonella showed no differences except at 4 wk, when activated bamboo charcoal had a 18% lower recovery of Salmonella (enrichment) compared to the control (88%). Similar to Experiment 1, the recovery of Salmonella from the litter was not significantly different among treatments, however an overall decrease in recovery by 4 wk with direct plating reoccurred. The pH of the duodenum and the crop were not different among treatments. Crop pH (6.0) for all treatments were significantly higher at wk 1 compared to wk 2 to 6. Charcoals had minimal effect on Salmonella recovery in the ceca, but following defeathering, broilers fed charcoals had significantly lower Salmonella recovery from breast skin (charcoals 5+/60 compared to control 8+/20). While the addition of charcoals to broilers feed did not significantly affect Salmonella recovery during production (from litter or ceca samples) there was a lower Salmonella recovery from breast skin following scalding and defeathering.

Control of Salmonella Enteritidis in turkeys using organic acids and competitive exclusion product.

AIM: To evaluate the use of organic acids (OAs) and competitive exclusion (CE) product administered continuously in the feed and transiently in drinking water on the control of Salmonella enterica subspecie enterica serotype Enteritidis (SE) prior to slaughter. METHODS AND RESULTS: The influence of treatments were evaluated on pH, population of the lactic acid bacteria (LAB) and bacteria of the family Enterobacteriaceae, concentration of volatile fatty acids and SE colonization in the crop and caecum. The birds were challenged with SE 24 h before being slaughtered, and then, the caeca and crop were removed and subjected to SE counts. Continuous administration of OAs reduced the population of bacteria from the Enterobacteriaceae family in both crop and caecum, positively influenced the butyric acid concentration and reduced SE colonization in the caecum. The diet supplemented with CE product positively influenced the quantity of LAB in the crop and caecum, elevated the butyric acid concentration and reduced both Enterobacteriaceae quantity and SE colonization in the caecum. There was no effect from administering the treatments via drinking water on the variables measured. CONCLUSIONS: Continuous supplementation in feed with OAs and CE product reduced SE colonization of the caeca. SIGNIFICANCE AND IMPACT OF THE STUDY: Supplementation of OAs and CE product in diet to turkeys can reduce the SE load, potentially leading to a lower contamination risk of meat during slaughter.

Egg production, egg quality and crop content of Rhode Island Red hens grazing on natural tropical vegetation.

The aim of this experiment was to study the suitability of the outdoor system for Rhode Island Red hens under the tropical conditions of southern Mexico. Twelve floor pens, each containing four birds, were divided randomly into two groups. The first group was raised indoors only, while each of the second group replicates had access to an outdoor area with natural-grown vegetation from 0800 to 1700 hours daily. Both groups fed ad libitum on a commercial layers diet. The results revealed no differences in body weight between treatments. The outdoor group recorded significantly higher egg laying rate (86.90 vs. 78.05 %), higher egg mass (50.66 vs. 45.30 g egg/hen/day), and higher feed intake (103.70 vs. 97.67 g/day) versus the indoor group. The outdoor group had eggs with darker yellow yolks (9.46 vs. 5.46), lower yolk, and higher albumen proportions (P < 0.05) versus the indoor group. The crop content of the outdoor hens consisted of 86.55 % concentrated feed, 6.30 % plant material, 2.27 % grit stones, 1.69 % snails and oyster shells, 1.25 % seeds, 0.95 % farm wastes, and 0.99 % insects, worms, and larvae. Of the outdoor hens, 43.1 % was observed to be in the range at each scanning time. The outdoor system in the tropics had beneficial effects on Rhode Island Red hen performance, and the hens utilized the outdoor area effectively and obtained various feed items.

Nutritional content of the diets of free-living scarlet macaw chicks in southeastern Peru.

To provide novel information on psittacine diets, we analyzed the texture, crude protein, crude fat, Ca, P (total), Mg, K, Na, S, Cu, Fe, and Zn concentrations of crop contents from 10 free-living scarlet macaw (Ara macao) chicks from lowland forests of southeastern Peru. We compared our results with nutrient concentrations of known wild parrot foods and published psittacine dietary recommendations to highlight similarities and differences and suggest future avenues of research. The diets were much coarser textured than those recommended for hand feeding. Soil in the diet provided an important source of Na, but Na levels were still lower than all recommendations. Concentrations of protein, Zn, K, Cu, and P (total) were near to or within the range of recommendations for captive psittacine birds. Fat, Ca, and Mg concentrations were greater in crop contents than in the average food plants and greater than published recommendations. The Na:K ratios were only one-twentieth of those recommended for young poultry. Future analyses should investigate the bioavailability of Fe, Ca, and Zn in these diets and the effects of varying concentrations of fat, Na, Ca, Mg, and Na:K ratio on psittacine growth and development.

Assessment of the nutritional status of indigenous scavenging chickens in Ada'a district, Ethiopia.

The nutritive values of scavenging feed resource bases and effects of season and chickens age on the latter were studied in smallholder farms in Aad'a, Ethiopia. The study included 210 households and 208 chickens. The mean weight of crop contents in all age groups ranged from 26.2 to 28.2 g, while it was 29.8 g and 24.7 g in the harvesting and non-harvesting seasons, respectively. Grains represented 48-49% of the mean weight of crop contents in all age groups and it was significantly higher (P < 0.05) during the harvesting season than the non-harvesting period in both age groups. Kitchen wastes were next in abundance (26-29%) and were significantly more abundant in non-harvesting season in growers only and in hens than in growers (P < 0.001). The dry matter, crude protein, crude fiber, calcium, phosphorous and metabolizable energy levels of crop contents were 91.1-92.5%, 12.9-15.5%, 4.17-7.07%, 0.43-0.90%, 0.28-0.38% and 3404.3-3636.2 Kcal, respectively. Crude protein, calcium and phosphorus levels were below the requirements for egg production and growth. The scavenging feed resource base was critically deficient in these nutrients during the harvesting season. As these nutrients are vital for production, supplementary feeds rich in these nutrients would probably result in increased egg production and optimum growth.

Prevalence of Campylobacter jejuni and Campylobacter coli in market-weight turkeys on-farm and at slaughter.

To monitor the effects of feed withdrawal on the prevalence of Campylobacter, market-weight turkeys from six farms were examined before and after perimarketing events (feed withdrawal, transport, and holding at the slaughterhouse). Prior to transport, birds (n = 30 per farm) were slaughtered on-farm, and viscera (crops, duodenum, jejunum, ileum, colon, ceca, gallbladder, and spleen) were removed on the premises. Within ca. 48 h, cohorts (n = 30 per farm) from the same flock were transported to a commercial abattoir, maintained in holding sheds, slaughtered, and the viscera were removed. No differences in the prevalence of Campylobacter spp. were evident when individual flocks were compared pre- and posttransport. However, when data for the six farms were combined, Campylobacter spp. were recovered (pre- versus posttransport) at comparable rates from the duodenum (74.7 versus 74.7%), ileum (87.3 versus 92.7%), ceca (64 versus 57%), colon (86.7 versus 80%), and spleen (0 versus 0%). After feed withdrawal, transport, and holding at the abattoir, there was an overall increase in Campylobacter spp. isolated from the gallbladder at the abattoir (14.7%) when compared with on-farm levels (0%, P < 0.05). When compared with on-farm levels (3%), the overall increase in Campylobacter spp. recovered from the crops of birds at the abattoir (24%) was significant (P < 0.05), which may be associated with a detectable decline in lactic acid in the emptied crop.

Seasonal variations in the crop contents of scavenging Helmeted Guinea Fowls (Numida meleagris, L.) in Parakou (Benin).

1. An experiment was carried out with 120 helmeted guinea fowls during one year in Parakou (Benin). Feed intake, ingredient and chemical composition, along with the nutritional adequacy of scavenging diets were measured during the rainy season (November-February) and dry season (March-October) in order to propose supplementation strategies. Ingredients found in crops were identified and allocated into 6 main categories (supplemental feed, seeds, green forages, animal materials, mineral matter and unidentified materials). 2. Mean dry weights of crop contents were significantly higher in the rainy than in the dry season. Amounts and proportions of supplemental feed and seeds were not significantly different between seasons, whereas those of green forage, animal materials and mineral matter were higher in rainy season. Supplemental feed, especially maize and sorghum, was the largest component of the crop content in both seasons. The most represented grass seeds were Panicum maximum (rainy season) and Rottboellia cochinchinensis (dry season). 3. Dietary concentrations of organic matter, non-nitrogen extract and metabolisable energy were higher in the dry season, while mineral concentrations were higher in the rainy season. There were no significant differences between the two seasons in dry matter, crude protein or crude fibre. 4. Scavenging provided insufficient nutrients and energy to allow guinea fowls to be productive. Therefore, more nutritionally balanced supplementary feed would be required during both seasons.

The influence of a fructooligosaccharide prebiotic combined with alfalfa molt diets on the gastrointestinal tract fermentation, Salmonella enteritidis infection, and intestinal shedding in laying hens.

Molting is a natural process, which birds undergo to rejuvenate their reproductive organs. The US poultry egg production industry has used feed withdrawal to effectively induce molt; however, susceptibility of Salmonella Enteritidis has encouraged the development of alternative methods. Previous research conducted in our laboratory showed that alfalfa is effective at molt induction and provides equivalent postmolt production numbers and quality when compared with feed withdrawal. In the attempt to further increase the efficacy of alfalfa molt diet and decrease the chicken susceptibility to Salmonella Enteritidis during molt, fructooligosaccharide (FOS) was added to a combination of 90% alfalfa and 10% layer ration in 2 levels (0.750 and 0.375%). Ovary and liver colonization by Salmonella Enteritidis in 3 and 2 of the 4 trials, respectively, were reduced (P 0.05) the production of cecal total volatile fatty acids when compared with hens undergoing feed withdrawal. However, in all 3 alfalfa molt diets, the concentrations of lactic acid were greater (P 0.05) were observed among hens fed alfalfa combined with FOS and hens fed alfalfa/layer ration without FOS. Overall, given the similarities between hens fed 0.750% FOS (H) and 0.375% FOS (L), molt diets combined with the lower level of FOS should be sufficient.

Changes in tissue nitrite concentration in the crop of the turkey poult in response to Salmonella typhimurium challenge.

The present study examines whether Salmonella typhimurium colonization of the crop of young turkeys influences nitrite concentration in the component tissues of the crop. Nitric oxide (NO) is the principal compound in biological samples that is converted into nitrites and NO is known to be a component of the early host response to infection. Challenge with S. typhimurium increased the concentration of nitrite in the crop wall of 3-wk-old turkey poults. The magnitude of the response was reduced at 8 h and absent at 48 h after challenge. As would be expected, S. typhimurium concentrations in the crop were markedly increased following challenge, and were nondetectable in control poults.

Effect of season and location on the crop contents of local and improved scavenging hens in northern Vietnam.

An experiment was carried out to determine the effects of season (dry and rainy), location (lowland and highland villages) and breed (local and improved) on the amount and physical and chemical composition of the scavenged feed. This was done by crop content analysis of a total of 192 Ri (local) and 192 Luongphuong (LP, improved) hens at 20 weeks of age. The mean fresh weights of the crop contents were 16.9 and 33.3 g, for the dry and rainy seasons, respectively (p < 0.001), 24.3 and 25.9 g, for the Ri and LP breeds, respectively (p < 0.001), and 25.0 and 25.3 g, for the lowland and highland village, respectively (p > 0.05). The proportions of contents were human food leftovers 38.4% and 24.3%, grains 20.9% and 33.7%, insects and worms 9.6% and 11.2%, and green materials 8.8% and 13.8%, for the dry and rainy seasons, respectively (p < 0.05). The proportion of green materials was higher in the LP hens and highland villages, while the proportion of grains was higher in the Ri hens and lowland village (p < 0.05). The dry matter, crude protein (CP), ether extract (EE), total ash (Ash), calcium (Ca), phosphorus, and metabolizable energy (ME) contents were significantly higher for the rainy season (p < 0.01), and CP, Ash, Ca and ME were higher for the LP hens. The crude fibre content was higher in the dry season, and in the Ri hens and highland village (p < 0.001). The total and essential amino acid concentrations were significantly higher in the rainy season, and in the LP hens (p < 0.05), but were not different between locations (p > 0.05). Nutrient intakes from scavenging were estimated at between 20% and 30% of requirements.

Evaluation of Salmonella enteritidis in molting hens after administration of an experimental chlorate product (for nine days) in the drinking water and feeding an alfalfa molt diet.

The method most commonly used to induce molting and stimulate multiple egg-laying cycles in laying hens for commercial egg production is to fast the hens. Unfortunately, increased risk of Salmonella enteritidis (SE) infection may result from the use of this method. Methods to stimulate multiple egg-laying cycles without increasing the risk of SE infection are needed. Hens over 50 wk of age were divided into 12 groups of 11 hens each and placed in individual laying cages. One week prior to dietary changes, hens were placed on an 8-h light and 16-h dark photoperiod that continued for the 9-d molt. All hens were challenged orally with 10(6) cfu of SE on the fourth day of the molt. Treatments were nonfed hens with distilled water (NFD), nonfed hens with the experimental chlorate product (ECP, which provided 15 mM chlorate ion) water (NFECP), alfalfa diets with distilled water (ALD), and alfalfa diets with ECP water (ALECP). In the NFD hens, 67% (log10 2.74) of the crops and 94% (log10 5.62) of the ceca were colonized, whereas for the NFECP hens significant reductions to 22% (log10 1.05) of the crops and 61% (log10 2.44) of the ceca were observed. In the ALD hens, 61% (log10 2.52) of the crops and 94% (log10 4.06) of the ceca were colonized. In the ALECP hens, highly significant reductions to 11% (log10 1.26) of the crops and 39% (log10 1.12) of the ceca were observed. When compared with the NFD hens, significant reductions in SE invasion of the ovary, liver, and spleen occurred in all other treatments, except the ovary in the ALD hens. The low alfalfa intake is probably a factor in our lowered protection against SE when compared with previous results. For several parameters, these results suggest that ECP or the combination of ECP and alfalfa may be a useful tool to reduce the risk of SE during an induced molt.

Diagnosis of zinc phosphide poisoning in chickens using a new analytical approach.

Approximately 200 chickens were found dead after the flooring of a slat-and-litter house was breached. No clinical signs of illness were observed in the surviving birds. During necropsy, rolled oats were found in the chickens' crops and gizzards, and the contents had a petroleum-like odor. Histopathologic examination revealed severe pulmonary edema and congestion of the chickens' lungs, hearts, livers, and kidneys. Based on the history and necropsy findings, zinc phosphide exposure was suspected. Diagnosis of zinc phosphide poisoning has previously been based on history of exposure, identification of the bait material in the gastrointestinal tract, and chemical detection of phosphine gas. However, currently available diagnostic methods are nonconfirmatory, and may produce false positive results. The objective of this case report was to determine whether the sudden death described in these chickens was caused by the ingestion of zinc phosphide, by developing a sensitive and highly specific gas chromatography/mass spectrometry (GC/MS) methodology for analysis of the gastrointestinal samples submitted to the laboratory. It was also found that the determination of zinc concentrations in liver or kidney tissue or stomach contents is not a reliable indicator of zinc phosphide poisoning.

Effects of drinking water treatment on susceptibility of laying hens to Salmonella enteritidis during forced molt.

Feed deprivation is used in the layer industry to induce molting and stimulate multiple egg-laying cycles in laying hens. Unfortunately, the stress involved increases susceptibility to Salmonella enteritidis (SE), the risk of SE-positive eggs, and incidence of SE in internal organs. Leghorn hens over 50 wk of age were divided into 4 treatment groups of 12 hens each in experiment 1 and 3 treatment groups of 12 hens in experiments 2 and 3; hens were placed in individual laying hen cages. Treatment groups were 1) nonmolted (NM) and received feed and distilled water for 9 d, 2) force molted by feed removal for 9 d and received distilled water, 3) force molted by feed removal for 9 d and received 0.5% lactic acid (LA) in distilled water. An additional group (4) in experiment 1 only was force molted by feed removal for 9 d and received 0.5% acetic acid in distilled water. Seven days before feed removal hens were exposed to an 8L:16D photoperiod, which was continued throughout the experiment. Individual hens among all treatments were challenged orally with 10(4) SE on d 4 of feed removal. When compared with the NM treatments, weight losses were significantly higher in the M treatments, regardless of water treatments. When compared with NM treatments, crop pH was significantly higher in the M treatment receiving distilled water. Crop pH was reduced to that of the NM controls by 0.5% acetic acid in the drinking water. No consistent significant changes were observed for volatile fatty acids. The number of hens positive for SE in crop and ceca after culture and the number of SE per crop and per gram of cecal contents were higher in the M treatments, when compared with the NM treatments, but there was no effect of addition of either of the acids to the drinking water. Additional research using different acid treatment regimens may provide a tool for reducing the incidence of SE in eggs and internal organs during and following molting of laying hens.

Scavenging pullets in Burkina Faso: effect of season, location and breed on feed and nutrient intake.

A study on scavenging local (n = 64) and crossbred (n = 64) pullets was undertaken in the dry and rainy seasons in two villages in Burkina Faso: Korea in the arid northern Sahelian region and Bounouna in the sub-humid south. After 4 weeks of scavenging, the birds were killed and the crop contents were subjected to physical and chemical analysis. Cereal grains, brans, green and dry forages, insects/worms and household leftovers were the main physical components. The proportion of cereal grains was higher in the rainy season, whereas the proportion of bran, peanut and sand/grit was higher in the dry season (p < 0.05). The proportion of kitchen waste and millet/milo grains was higher in local than in crossbred birds, whereas the opposite was the case for millet/milo bran (p < 0.05). Rice and local beer residues were not found in the crops of birds from Korea. Dry matter, ash, crude fibre and potassium contents were higher in the dry season (p < 0.05), while calculated metabolizable energy content was higher in the rainy season (p < 0.05). There were no location or breed effects on chemical composition parameters (p > 0.05), except that potassium content was higher in Korea. Mean live weight at slaughter was 806 +/- 22.0 g (local breed) and 881 +/- 22.0 g (crossbreds) (p < 0.05). Digestive organ weights, including contents, were higher for crossbred birds (p < 0.05). Gastrointestinal tract percentage was higher in the rainy season and in Bounouna (p < 0.05). The nutrient composition of the crop contents indicates the need for supplementation, particularly of protein, for higher levels of production.

Comparison of zinc acetate and propionate addition on gastrointestinal tract fermentation and susceptibility of laying hens to Salmonella enteritidis during forced molt.

Feed deprivation is the most common method used to induce molting and stimulate multiple egg-laying cycles in laying hens for commercial egg production. Unfortunately, an increased risk of Salmonella enteritidis (SE) colonization may result from the use of this method. Methods to stimulate multiple egg-laying cycles without increasing the risk of SE are needed. In each of 3 experiments, hens over 50 wk of age were divided into groups of 12 and placed in individual laying cages. One week before dietary changes, hens were put on an 8L:16D photoperiod that continued for the 9-d experimental period. Hens in all treatments were challenged orally with 10(4) cfu of SE on the fourth day. Treatments were full fed hens (nonmolted, NM), nonfed hens (molted, M), a zinc acetate diet (ZAC), and a zinc propionate diet (ZPR). The zinc diets contained 10,000 mg of zinc per kilogram of diet. Body weight losses were significantly higher in the M, ZPR, and ZAC treatments than in the NM treatment. Crop lactic acid decreased more in M, ZPR, and ZAC treatments than in NM hens in trial 2. Crop pH was significantly (P < 0.05) lower in NM hens than in M, ZAC, and ZPR hens in trial 2. Although cecal individual or total volatile fatty acids (VFA), and lactic acid were not significantly (P > 0.05) different between NM hens and M, ZAC and ZPR hens in trial 1, lactic acid was significantly (P < 0.05) higher in NM hens than in M, ZAC and ZPR hens (trial 2), and cecal total VFA were lower in M hens than in NM, ZAC and ZPR hens (trial 3). Colonization of SE in the crop and ceca was higher in the M and ZPR hens (trials 1 and 2). Liver, spleen, or ovary invasion by SE was higher in the M and ZPR hens (trials 1 and 2) than in NM hens. At the zinc concentration used in these studies, the zinc dietary regimens may be effective for reducing the risk of SE during induced molt.

Effect of organic acids in drinking water for young broilers on Campylobacter infection, volatile fatty acid production, gut microflora and histological cell changes.

Water is a prominent vehicle for Campylobacter spread throughout a chicken flock. The aim of this study was to evaluate the effect of organic acids administered through the drinking water, as a decontamination method, on gut microflora and the development of lesions in the gastrointestinal tracts of young broilers inoculated with 2 different doses of Campylobacter. The results revealed that most of the chickens were infected with Campylobacter at the end of the experiment. The drinking water was free of Campylobacter throughout the study. No difference of volatile fatty acid levels between treatment and control groups was observed in the crop and cecal contents. In the cecal contents, the total aerobic bacteria numbers were significantly higher in the treatment groups compared with the control groups (P < 0.01 and P < 0.04, respectively). Moreover, no damaged epithelial cells were observed in the chicken gut due to consumption of acidified drinking water. Acidified drinking water could therefore play a crucial role in a biosecurity strategy of preventing Campylobacter spread via drinking water in broiler flocks.

Effects of high zinc diets using zinc propionate on molt induction, organs, and postmolt egg production and quality in laying hens.

This study was conducted to determine the ability of an alternative salt form of 1% Zn, Zn propionate, to induce molt in 66-wk-old hens. The hens were randomly assigned to 4 treatment groups of 27 or 28 birds each: a) molted conventionally by feed withdrawal, b) 1% Zn as Zn acetate, c) 1% Zn as Zn propionate, or d) nonmolted control for 9 d. Feed intake was (P < 0.05) depressed in Zn acetate and Zn propionate hens when compared with nonmolted control hens during the 9 d. Ovary weights of hens undergoing feed withdrawal, Zn acetate, or Zn propionate were not (P > 0.05) different from each other, but all were (P < 0.05) lighter than the ovary weights of nonmolted control hens. Zinc concentrations in the kidney and liver were (P < 0.05) increased in Zn acetate and Zn propionate molted hens when compared with nonmolted hens on the control diet or hens molted by feed withdrawal. Bone ash values were (P < 0.05) increased for Zn acetate and Zn propionate molted hens or nonmolted control hens as compared with molted hens on feed withdrawal. Over the entire 3-mo postmolt period, there were no significant differences in interior egg qualities, but egg weights from hens fed Zn propionate were (P < 0.05) heavier than those from hens on feed withdrawal. The data of the current study demonstrated that feeding a Zn propionate (1% zinc)-supplemented diet can induce molt.

Passage of Salmonella through the crop and gizzard of broiler chickens fed with fermented liquid feed.

In vivo experiments were conducted in order to investigate the passage and bacterial reduction of Salmonella in the crop and gizzard of chickens when fed two different feeds. The chickens were fed dry conventional feed and fermented liquid feed. The fermented feed contains a relatively high concentration of lactic and acetic acid and lactobacilli. One and three week old broiler chickens were necropsied at short intervals after inoculation with Salmonella Enteritidis. Counts of Salmonella from the crop, gizzard, duodenum, caecum and colon/rectum were obtained. This revealed a sharper decrease of Salmonella in the anterior parts of the gastro-intestinal tract in chickens fed with fermented feed than in chickens fed dry feed. It is therefore concluded that fermented feed improves the barrier formed by the crop and gizzard. The reduction of Salmonella is fully realised in the crop and gizzard. The lower intestinal compartment did not show a substantial effect on the reduction of Salmonella. The performed in vivo method appeared to be an appropriate way to study intervention strategies that aim to control Salmonella by improving the barrier function of the upper gastro-intestinal tract.

Expression of the hilA Salmonella typhimurium gene in a poultry Salm. enteritidis isolate in response to lactate and nutrients.

Pathogens express virulence genes in response to the combination of environmental conditions present in the host environment. The crop is the first gastrointestinal environment encountered in birds. However, feed withdrawal alters the crop environment resulting in an increased pH, and decreased concentrations of lactate, glucose and amino acids compared with unmoulted birds. Salmonella enteritidis infections increase significantly in hens that have been force moulted by feed withdrawal. The present study examined the effects of pH, carbohydrate sources, amino acids and lactate on expression of Salm. enteritidis virulence by measuring expression of hilA. The hilA gene encodes a transcriptional activator that regulates expression of Salmonella virulence genes in response to environmental stimuli. HilA expression was determined using a poultry isolate of Salm. enteritidis carrying a hilA-lacZY transcriptional fusion from Salm. typhimurium. The media used were Luria Bertani (LB) broth and LB broth diluted 1:5 (DLB). The expression of hilA was 2.9-fold higher in DLB broth compared with LB broth which suggested that there is a nutritional component to the regulation of hilA. Addition of 0.2% glucose, fructose or mannose to LB and DLB reduced hilA expression 1.5 to twofold. Addition of 0.2% Casaminoacids, arabinose, fucose, or lactose had little effect on hilA expression. Lactate (25 and 50 mmmol 1-1) reduced hilA expression at pH 6, 5 and 4, with the lowest expression occurring at pH 4. Based on these results it appears that the composition of the crop lumen could potentially influence Salm. enteritidis virulence expression.

Survival of Salmonella in the crop contents of market-age broilers during feed withdrawal.

Recent studies have indicated that crop contamination increases during preslaughter feed withdrawal and that contaminated crop contents may serve as an important source of Salmonella entry into poultry processing plants. During the present study, we evaluated the effect of preslaughter feed withdrawal on crop pH and Salmonella crop contamination in broilers from three commercial broiler flocks. The effect of experimental feed withdrawal on crop pH, lactic acid concentration, and Salmonella crop contamination was also evaluated in market-age broilers challenged experimentally with Salmonella typhimurium. Crop pH increased significantly (P < 0.05) from 3.64 +/- 0.25 before feed removal to 5.14 +/- 0.72 after 8 hr of feed withdrawal in broilers from commercial flocks. The incidence of Salmonella crop contamination in the commercial broilers increased (P < 0.05) from 3.3% before feed removal to 12.6% after 8 hr of feed withdrawal. Similarly, crop pH increased (P < 0.05) by a magnitude of approximately 1 unit in broilers after 8 hr of experimental feed withdrawal. The population of S. typhimurium in the crops of the experimentally challenged broilers increased (P < 0.05) by approximately 1 log unit during the 8-hr experimental feed withdrawal. The concentration of lactic acid in the crop of the broilers during experimental feed withdrawal decreased (P < 0.01) from a range of 119-135 mumol/ml before feed removal to a range of 22-32 mumol/ml after 8 hr of feed withdrawal. The results indicated that feed withdrawal resulted in a decrease in lactic acid in the crop, accompanied by an increase in crop pH, and an increase in Salmonella crop contamination.