Foodborne Salmonella ecology in the avian gastrointestinal tract.

Foodborne Salmonella continues to be a major cause of salmonellosis with Salmonella Enteritidis and S. Typhimurium considered to be responsible for most of the infections. Investigation of outbreaks and sporadic cases has indicated that food vehicles such as poultry and poultry by-products including raw and uncooked eggs are among the most common sources of Salmonella infections. The dissemination and infection of the avian intestinal tract remain somewhat unclear. In vitro incubation of Salmonella with mammalian tissue culture cells has shown that invasion into epithelial cells is complex and involves several genetic loci and host factors. Several genes are required for the intestinal phase of Salmonella invasion and are located on Salmonella pathogenicity island 1 (SPI 1). Salmonella pathogenesis in the gastrointestinal (GI) tract and the effects of environmental stimuli on gene expression influence bacterial colonization and invasion. Furthermore, significant parameters of Salmonella including growth physiology, nutrient availability, pH, and energy status are considered contributing factors in the GI tract ecology. Approaches for limiting Salmonella colonization have been primarily based on the microbial ecology of the intestinal tract. In vitro studies have shown that the toxic effects of short chain fatty acids (SCFA) to some Enterobacteriaceae, including Salmonella, have resulted in a reduction in population. In addition, it has been established that native intestinal microorganisms such as Lactobacilli provide protective mechanisms against Salmonella in the ceca. A clear understanding of the key factors involved in Salmonella colonization in the avian GI tract has the potential to lead to better approach for more effective control of this foodborne pathogen.

Evaluation of an experimental chlorate product as a preslaughter feed supplement to reduce salmonella in meat-producing birds.

A study was conducted to evaluate the effect of experimental chlorate product (ECP) feed supplementation on Salmonella Typhimurium (ST) in the crop and ceca of market-age broilers. In trial 1, 160 market-age broilers were randomly assigned to 8 treatment groups and replicated twice, with 20 broilers per pen for 1 wk. Trial 2 used the same design, but used 80 market-age broilers with 10 broilers per pen. Treatments were as follows: 1) control feed + double-distilled drinking water (dd H(2)O); 2) control + 18.5% experimental zeolite carrier with dd H(2)O; 3 to 7) control feed supplemented with 0.5, 1.0, 5.0, 10.0, or 18.5% of a feed grade ECP + dd H(2)O; 8) control feed + 1x ECP (0.16% w/v; containing 15 mM chlorate ion equivalent) added to dd H(2)O. Seven-week-old broilers were provided experimental treatments for 7 d, killed, and then ceca and crops were removed and evaluated for ST. Broilers fed 5 to 18.5% ECP or water ECP had a significantly lower (P < 0.05) incidence of ST in the crop (36 to 38% and 14%, respectively) when compared with the control (60%). Broilers fed 10% ECP or water ECP had significantly lower ST crop concentrations (1.03 log(10) and 0.38 log(10) ST/g, respectively) when compared with broilers fed a control diet (1.54 log(10) ST/g). Crop and ceca ST incidence (32 to 48%) and concentration (1.00 to 1.82 log(10) ST/g) were significantly lower in broilers fed 5 to 18.5% ECP as compared with the control (78%; 2.84 log(10) ST/g). Broilers fed 5% or greater ECP had significantly higher water consumption (380 to 580 mL water/d) and litter moisture (31 to 56%) when compared with the control (370 mL water/d; 23% moisture). Only broilers fed 18.5% ECP had significantly lower 7-wk BW (2.77 kg of BW) when compared with the controls (3.09 kg of BW). Average daily gains were significantly depressed in broilers fed 10 or 18.5% ECP compared with the controls. These results indicate broilers supplemented with feed

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.

In vitro fermentation response of laying hen cecal bacteria to combinations of fructooligosaccharide prebiotics with alfalfa or a layer ration.

The objective of this in vitro study was to evaluate the effects of combining a prebiotic with alfalfa on fermentation by laying hen cecal bacteria. Cecal contents from laying hens were diluted to a 1:3,000 concentration with an anaerobic dilution solution and added to serum tubes filled with ground alfalfa or a layer ration with or without fructooligosaccharide (FOS) prebiotic. Samples were processed in an anaerobic hood, pressurized by using a pressure manifold, and incubated at 37 degrees C. Volatile fatty acid (VFA) and lactic acid concentrations were quantified at 6 and 24 h of substrate fermentation. In this study, fermentation of alfalfa resulted in greater production of acetate, VFA, and lactic acid compared with the layer ration. Although with a relative inconsistency in data between trials, the amendment of FOS to both alfalfa and the layer ration appeared to further increase fermentation as demonstrated by overall higher propionate, butyrate, VFA, and lactic acid concentrations. The effect was more pronounced after 24 h of fermentation, implying time constraints for the optimal production of fermentation products in the chicken gastrointestinal tract. These data indicate that in vitro cecal fermentation can be enhanced by the addition of FOS.

Behavioral responses of laying hens to different alfalfa-layer ration combinations fed during molting.

Induced molting by feed withdrawal has been a common practice in the commercial layer industry and usually involves the removal of feed for a period of up to 14 d. However, this is a practice that is believed to adversely influence the welfare of the hens and there is a need to examine behavioral responses to alternative molt regimens. The behavioral patterns of hens on 90% alfalfa:10% layer ration, 80% alfalfa:20% layer ration, and 70% alfalfa:30% layer ration molt diets were compared with feed withdrawal (FW) hens, and fully fed (FF) hens. The White Leghorn laying hens were approximately 54 wk old and were placed in 3 identical climate-controlled rooms. The hens were individually housed in 2-tier wire battery cages and provided treatment rations and water ad libitum. Nonnutritive pecking, walking, drinking, feeder activity, preening, aggression, and head movement were quantified during two 10-min periods each day for 6 hens from each treatment. Over the 9-d treatment period, hens in the FW, 70% alfalfa:30% layer ration, and 80% alfalfa:20% layer ration groups spent significantly more time walking than hens in the 90% alfalfa:10% layer ration group. The FF and 70% alfalfa:30% layer ration hens spent half as much time preening, whereas the FW hens displayed nearly twice as much nonnutritive pecking when compared with other treatments. Most differences in head movements occurred at the beginning of the molt period, whereas during the last half of molt, alfalfa-fed hens exhibited feeder activity similar to FF hens, and all were significantly higher than that of FW hens. After some initial adjustment by the hens, consumption of alfalfa molt diets appeared to reduce nonnutritive pecking behavior, which is characteristically associated with FW hens.

Behavior of laying hens on alfalfa crumble molt diets.

Several dietary alternatives to feed withdrawal have been proposed to induce a molt in laying hens. This study compared the behavior of laying hens on an alfalfa crumble diet (ALC) to hens that were either on a conventional layer diet (FF) or hens that had feed withdrawn (FW) during a 9-d trial. Each treatment consisted of 24 hens (3 hens per battery cage), and treatment began after a 2-week acclimation period. Video cameras connected to a digital multiplexer recorded the behavior of the hens. The percentages of observations performing nonnutritive pecking, feeder activity, drinking, walking, preening, head movement, and aggression were quantified for two 10-min periods at daily intervals. The FF hens spent significantly more (P < or = 0.05) time drinking than the other treatments, whereas FW hens displayed the most head movements. From d 1 through 7, FW hens walked less than ALC hens except on d 8 when FW hens walked more than ALC and FF hens. On d 4 and 6, the FW hens spent an increased amount of time preening compared with FF hens until the last few days of the molt period. For the most part, FW hens generally displayed more nonnutritive pecking than ALC and FF hens throughout the molt period. However, FW hen visits to the feeders declined as the trial proceeded, whereas ALC and FF hens generally spent more time at the feeder. In summary, the ALC diet showed potential as an alternative to FW for inducing a molt in laying hens based on reduced nonnutritive pecking behavior, head movements, and greater feeding activity.

Organ weight and serum triglyceride responses of older (80 week) commercial laying hens fed an alfalfa meal molt diet.

Since one of the costs in the commercial egg industry is that of replacement pullets, commercial egg layer managers have opted to induce molt older hens in order to extend their productive life for additional egg laying cycles. Conventional molt induction involves the complete removal of feed for several days. However, this management practice can lead to deleterious physiological responses by the hen and subsequent susceptibility to infection by pathogens. Consequently less stressful molting regimens involving the feeding of low energy diets such as alfalfa have been developed. In this study, 80 week old laying hens that were deprived of feed or fed alfalfa meal during a nine day induced molt. Full fed hens were used as the control. On day 8 serum triglycerides were quantified and on day 9 hens were euthanized and the liver, spleen, heart, intestine, pancreas, ovary, and kidney were collected and weighed. Intestinal weight were highest in the non-molted hens, lower in the hens fed alfalfa, and lower still in the hens deprived of feed. Molted hens exhibited reduced weights of liver, heart, ovary, and pancreas compared to the non-molted hens. Serum triglycerides were highest in the non-molted hens, less in feed deprived hens, and the lowest in alfalfa fed hens. These results suggest that a comparable molt could be achieved with feeding alfalfa meal to 80 week hens compared to feed deprivation.

Immunological cell and serum metabolite response of 60-week-old commercial laying hens to an alfalfa meal molt diet.

The practice of induced molting involves the restriction of light, feed removal and optionally water for 5-14 days. However, there is growing concern regarding feed removal and animal welfare issues. With this in mind, alternative diets have been developed to produce similar molting effects as that of feed deprivation. Alfalfa, which largely consists of insoluble fiber, can be used as a molting diet. In this study, heterophil and lymphocyte counts, serum chemistry, and organ weight parameters were evaluated in hens that were deprived of feed or fed alfalfa during a nine day induced molt. Full-fed hens were used as the control. Blood serum parameters assessed included calcium, magnesium, glucose, total protein, ketone bodies, uric acid, and cholesterol. White blood cells were counted and categorized by cell type. On the ninth day of the trial, the hens were euthanized and the liver, spleen, heart, intestine, pancreas, ovary, oviduct, and kidney were collected and weighed. On day 8 birds molted with alfalfa or by feed deprivation had significantly higher (P<0.05) levels of ketone bodies and cholesterol and lower levels of calcium, and magnesium compared to the full-fed hens while birds molted by feed deprivation exhibited significantly lower levels of uric acid. Birds molted by both methods exhibited significant reductions in ovary, oviduct, liver and pancreas weights and increased spleen weights when compared to the non-molted hens. On days 0, 2, and 6 there were no significant differences (P>0.05) in either heterophil or lymphocyte percentages. However, heterophil percentages were higher in feed withdrawal birds than full-fed birds on day 4 but lymphocyte percentages were higher in full-fed birds compared to feed withdrawal birds. On day 8 of the induced molt lymphocyte percentages were higher from full-fed birds when compared to feed withdrawal birds but no significant differences were detectable for heterophil percentages. Based on reproductive organ weight loss and changes in serum and immunological responses of birds during molt, it appears that alfalfa meal can be an effective molt induction alternative.

Molting in Salmonella enteritidis-challenged laying hens fed alfalfa crumbles. III. Blood plasma metabolite response.

The objective of this study was to examine an alfalfa crumble diet as an alternative molt diet and compare the physiological response of hens to the responses of feed-deprived molted hens. Hens >50 wk old were placed into 6 treatment groups (12 hens per group in trial 1 and 10 hens per group in trial 2): nonmolted Salmonella enterica serovar Enteritidis positive (FF+), nonmolted Salmonella Enteritidis negative (FF-), feed withdrawal Salmonella Enteritidis positive (FW+), FW Salmonella Enteritidis negative (FW), alfalfa Salmonella Enteritidis positive (ALC+), and ALC Salmonella Enteritidis negative (ALC-). Each hen in the Salmonella Enteritidis-positive groups was challenged on the fourth day of the study with 1 mL of 10(6)-cfu Salmonella Enteritidis. Blood was collected on d 2, 5, 9, and 12 of the trial. Blood plasma was collected and metabolite concentrations were analyzed for glucose, calcium, cholesterol, uric acid, total protein, and triglycerides. The feed intakes of the FF hens were 4- to 6-fold greater (P

Molting in Salmonella enteritidis-challenged laying hens fed alfalfa crumbles. IV. Immune and stress protein response.

Immunological responses of molting hens either infected or not infected with Salmonella enterica serovar Enteritidis were compared in 2 trials with Single Comb White Leghorn hens >50 wk old. The hens were placed into 6 treatment groups with 12 hens per group: nonmolted Salmonella Enteritidis positive (FF+), non-molted Salmonella Enteritidis negative (FF-), feed withdrawal Salmonella Enteritidis positive (FW+), FW Salmonella Enteritidis negative (FW-), alfalfa Salmonella Enteritidis positive (ALC+), and ALC Salmonella Enteritidis negative (ALC-). Each hen in the Salmonella Enteritidis-positive groups was challenged on d 4 of the study with 1 mL of 10(6)-cfu Salmonella Enteritidis, and diets were administered for 12 d. Blood samples were collected on d 2, 5, 9, and 12, and blood smears were enumerated for heterophil to lymphocyte (H:L) ratios. Serum samples were also analyzed for alpha(1)-acid glycoprotein (AGP) levels and antibody level. On d 12, hens were euthanized and bile samples from the gall bladder and sections of the ileum and the ceca were collected, and an ELISA was used to determine the intestinal, serum, and bile antibody responses. The FW+ hens produced more (P

Molting in Salmonella Enteritidis-challenged laying hens fed alfalfa crumbles. II. Fermentation and microbial ecology response.

The objective of this study was to examine microbial population shifts and short-chain fatty acid (SCFA) responses in the gastrointestinal tract of Salmonella Enteritidis-challenged molted and nonmolted hens fed different dietary regimens. Fifteen Salmonella-free Single Comb Leghorn hens (>50 wk old) were assigned to 3 treatment groups of 5 birds each based on diet in 2 trials: 100% alfalfa crumbles (ALC), full-fed (FF, nonmolted) 100% commercial layer ration, and feed withdrawal (FW). A forced molt was induced by either a 12-d alfalfa diet or FW. In all treatment groups, each hen was challenged by crop gavage orally 4 d after molt induction with a 1-mL inoculum containing 10(6) cfu of Salmonella Enteritidis. Fecal and cecal samples (d 4, 6, 8, 11, and necropsy on d 12) were collected postchallenge. Microbial population shifts were evaluated by PCR-based 16S ribosomal RNA gene amplification and denaturing gradient gel electrophoresis, and SCFA concentrations were measured. Total SCFA in fecal and cecal contents for FW molted hens were generally lower (P < or = 0.05) in the later stages of the molt period when compared to ALC and FF treatment groups. The overall trend of SCFA in cecal and fecal samples exhibited similar patterns. In trials 1 and 2, hens molted with ALC diet generally yielded more similar amplicon band patterns with the FF hens in both fecal and cecal samples by the end of the molting period than with FW hens. The results of these studies suggest that ALC molted hens supported microflora and fermentation activities, which were more comparable to FF hens than FW hens by the end of the molting period.

Molt performance and bone density of cortical, medullary, and cancellous bone in laying hens during feed restriction or alfalfa-based feed molt.

A study was conducted to evaluate the effects of alfalfa-based molt diets on molting performance and bone qualities. A total of 36 Single Comb White Leghorn hens were used for the study. There were 6 treatments: pretrial control (PC), fully fed (FF), feed withdrawal (FW), 90% alfalfa:10% layer ration (A90), 80% alfalfa:20% layer ration (A80), and 70% alfalfa:30% layer ration (A70). For the PC treatment, hens were euthanized by CO(2) gas, and bones were collected before molt was initiated. At the end of the 9-d molt period, hens were euthanized, and femurs and tibias were collected to evaluate bone qualities by peripheral quantitative computed tomography, mechanical testing, and conventional ash weights. The hens fed alfalfa-based molt diets and FW stopped laying eggs within 5 d after molt started, and all hens in these groups had reduced ovary weights compared with those of the FF hens. In the FW and A90 groups, total femur volumetric bone mineral densities (vBMD) at the midshaft were significantly lower, but those of the A80 and A70 groups were not significantly different from the values for the PC and FF hens. In cortical bone density, the midshaft tibial vBMD were significantly higher for FF and A70 hens than for PC hens. The medullary bone densities at the midshaft femur or tibia of the FW, A90, A80, and A70 hens were reduced compared with those of the PC hens. Femur cancellous densities at the distal femur for the FW and A90 hens were significantly reduced compared with those of the PC and FF hens. The FW, A80, and A70 hens yielded significantly higher elastic moduli, and the A80 hens had higher ultimate stress compared with the PC hens, suggesting that the mechanical integrity of the midshaft bone was maintained even though the medullary vBMD was reduced. These results suggest that alfalfa-based molt diets exhibit molt performance similar to FW, that medullary and cancellous bones are labile bone compartments during molting, and that alfalfa-based molt diets may be beneficial to maintain the mechanical properties of bones during molt.

Molting in Salmonella enteritidis-challenged laying hens fed alfalfa crumbles. I. Salmonella enteritidis colonization and virulence gene hilA response.

The objectives of this study were to enumerate Salmonella enterica serovar Enteritidis colonization in fecal, cecal, and internal organs, and to compare the level of virulence gene expression (hilA) of experimentally challenged laying hens fed different dietary molt-induction regimens. Twelve Salmonella-free Single Comb Leghorn hens (>50 wk old) hens were randomly assigned to each of 6 treatment groups designated based on diet in 2 trials: 1) feed withdrawal Salmonella Enteritidis-positive (FW+), 2) fully fed Salmonella Enteritidis-positive (FF+), 3) 100% alfalfa crumble Salmonella Enteritidis-positive (ALC+), 4) feed withdrawal Salmonella Enteritidis-negative, 5) fully fed Salmonella Enteritidis-negative, and 6) 100% alfalfa crumble Salmonella Enteritidis-negative. A forced molt was induced by a 12-d alfalfa diet and a feed-withdrawal regimen. On d 4 of the molt, all hens in groups 1, 2, and 3 were challenged by crop gavage with 1 mL of inocula containing approximately 10(6) cfu of nalidixic acid- and novobiocin-resistant Salmonella Enteritidis (phage type 13A). At the conclusion of both trials, all hens were euthanized and Salmonella Enteritidis colonization was enumerated in the cecal contents, liver, spleen, and ovaries. In addition, fecal (d 4 and 8) and cecal samples (necropsy at d 12) were collected postchallenge from treatment groups 1, 2, and 3 (Salmonella Enteritidis-positive) to quantify hilA expression by PCR. In both trials, all nonchallenged birds were Salmonella Enteritidis-negative; therefore, no further analysis was done. In trial 1, a 2-fold reduction in Salmonella Enteritidis colonization was observed in the ALC+ hens (log10 Salmonella Enteritidis of 1.99) compared with the FW+ hens (log(10) Salmonella Enteritidis of 3.89). In trial 2, a 4-fold reduction in Salmonella Enteritidis colonization was observed in the ALC+ hens (log(10) Salmonella Enteritidis of 1.27) compared with the FW+ hens (log(10) Salmonella Enteritidis of 5.12). In trial 2, Salmonella Enteritidis colonization in spleens was higher (P 0.05). In trial 2, hilA expression in FW+ hens was higher (P

In vitro anaerobic incubation of Salmonella enterica serotype Typhimurium and laying hen cecal bacteria in poultry feed substrates and a fructooligosaccharide prebiotic.

The objective of this study was to investigate the effect of combining a prebiotic with poultry feeds on the growth of Salmonella enterica serotype Typhimurium (ST) in an in vitro cecal fermentation system. Cecal contents from three laying hens were pooled and diluted to a 1:3000 concentration in an anaerobic dilution solution. The cecal dilution was added to sterile test tubes filled with alfalfa and layer ration with and without fructooligosaccharide (FOS). Two controls containing cecal dilutions and anaerobic dilution solution were used. The samples were processed in the anaerobic hood and incubated at 37 degrees C. Samples were inoculated with Salmonella at 0 and 24h after in vitro cecal fermentation and plated at 0 and 24h after inoculation with ST. Plates were incubated for 24h and colony forming units (CFU) enumerated. The samples immediately inoculated with ST without prior cecal fermentation did not significantly lower ST counts 24h later. However, samples pre-incubated for 24h with cecal microflora prior to ST inoculation exhibited reduced ST CFU by approximately 2 logarithms, with the most dramatic decreases seen in alfalfa and layer ration combined with FOS. The addition of FOS to feed substrate diets in combination with cecal contents acted in a synergistic manner to decrease ST growth only after ST was introduced to 24h cecal incubations.

Comparison of in vitro fermentation and molecular microbial profiles of high-fiber feed substrates incubated with chicken cecal inocula.

High fiber and nonstarch polysaccharide-based poultry diets have received more interest recently for retaining or promoting beneficial gastrointestinal microbial populations. The objective of this study was to investigate and compare the in vitro potential fermentability of high-fiber feed substrates (HFFS) by laying hen cecal microflora. Feed sources examined included soybean meal, soybean hull, beet pulp, wheat middlings, ground sorghum, cottonseed meal, 100% alfalfa meal, 90% alfalfa + 10% commercial layer ration, 80% alfalfa + 20% commercial layer ration, and 70% alfalfa + 30% commercial layer ration. Cecal contents and HFFS were incubated anaerobically in serum tubes at 39 degrees C for 24 h. Samples from 2 trials were analyzed at 0 and 24 h for short-chain fatty acids (SCFA). Short-chain fatty acids in samples at 0 h were subtracted from 24-h samples to determine the net production of SCFA. In both trials involving HFFS incubations with cecal inocula, acetate production was highest followed by propionate and butyrate whereas isobutyrate and isovalerate production were in trace amounts. In trial 2, detectable valerate production appeared to consistently occur with alfalfa-based HFFS. It was clear that SCFA production was largely dependent upon HFFS, because cecal inoculum alone yielded little or no detectable SCFA production. For HFFS incubations without cecal inocula, acetate production was highest; propionate and butyrate were similar, and isobutyrate, valerate, and isovalerate production were in trace amounts. Polymerase chain reaction-based denaturing gradient gel electrophoresis results from both trials indicated 69 and 71% similarity for comparison of all feed mixtures in trials 1 and 2, respectively. All alfalfa-based HFFS yielded a higher similarity coefficient in trial 2 than in trial 1 with a band pattern of 90% similarity; diets containing 90% alfalfa + 10% commercial layer ration and 80% alfalfa + 20% commercial layer ration in trial 2 formed a subgroup with a 94% microbial similarity coefficient. These data suggest that high fiber sources may contribute to the fermentation and microbial diversity that occurs in the ceca of laying hens.

The effect of an experimental chlorate product on Salmonella recovery of turkeys when administered prior to feed and water withdrawal.

Previously, an experimental chlorate product (ECP) has been observed to reduce Escherichia coli and Salmonella infections in swine, cattle, and broilers. The following studies were performed to investigate the effects of different concentrations and durations of administering ECP on crop and ceca Salmonella typhimurium (ST) colonization of turkeys. In 2 separate trials, each conducted with 2 replicates, 15-wk-old turkey toms were challenged with 10(7) to 10(9) cfu of ST. In Experiment 1, toms were administered 0, 0.5, 1.0, 2.0, or 4.0x of ECP (a 1.0x concentration is equivalent to a 15 mM chlorate ion concentration) in the drinking water for 38 h. In Experiment 2, toms were administered a 2x concentration of ECP in the drinking water for 0, 14, 26, or 38 h prior to water withdrawal. All treatments were followed by a 10-h water withdrawal and an 8-h feed withdrawal prior to organ sampling. In Experiment 1, turkeys provided ECP had significantly (P < 0.05) lower populations and incidences of crop (>1.4 log reduction) and ceca (>0.6 log reduction) ST as compared with control birds (2.1 and 0.94 log ST average for all trials, respectively), with little or no additional benefit from administration of higher ECP concentrations. In Experiment 2, toms provided ECP had lower populations of crop (>2.2 log reduction) and ceca (>1.5 log reduction) ST when compared with controls (3.1 and 1.8 log ST, respectively). Again, there appeared to be little benefit in longer administration intervals on quantitative reduction of ST. These experiments suggest that the ECP significantly reduces Salmonella colonization in commercial turkeys when administered prior to feed and water withdrawal.

Effect of various combinations of alfalfa and standard layer diet on susceptibility of laying hens to Salmonella enteritidis during forced molt.

Feed deprivation is commonly used by the poultry industry to induce molting and stimulate multiple egg-laying cycles. However, feed deprivation has been observed experimentally to increase susceptibility of poultry to Salmonella infections. Previous studies indicated that alfalfa was efficacious in reducing Salmonella; the present investigation was designed to evaluate the efficacy of combined alfalfa and layer diets on Salmonella colonization. Leghorn hens over 50 wk of age were divided into 12 groups of hens and placed in individual laying cages. One week prior to dietary changes, hens were put on an 8L:16D photoperiod that continued for the 9-d experiment. Hens were challenged orally with 104 cfu of Salmonella Enteritidis (SE) on d 4 of treatment and cultured for SE at the termination of the 9-d study. Two independent experiments were conducted consisting of the following treatment groups: nonfed hens, full-fed standard commercial layer diet, 100% alfalfa meal diet, a 90% alfalfa meal/10% standard commercial layer diet, and a 70% alfalfa meal/30% standard commercial layer diet. When evaluating SE colonization in the ceca (Exp. 1), a reduction (P < 0.05) was seen in the 100% alfalfa meal diet and the 70% alfalfa meal/30% standard commercial layer diet treatment groups when compared with the controls with Log10 values of 0.54, 0.44, and 2.82, respectively. Evaluation of physiological parameters showed the alfalfa treatment groups had reductions (P < 0.05) in weight loss, ovary weight, and feed consumption when compared with the full-fed standard commercial layer diet hens, and these results were comparable with the nonfed hens. In Exp. 2, all of the treatment groups had a reduction (P < 0.05) in SE colonization of the ceca when compared with the controls. There were also similar physiological reductions in weight loss, ovary weight, and feed consumption when birds were fed the alfalfa diets in Exp. 2. These data suggest that alfalfa can potentially be combined with layer ration to limit SE infection and still induce a molt comparable with feed withdrawal.

Effects of alfalfa and fructooligosaccharide on molting parameters and bone qualities using dual energy X-ray absorptiometry and conventional bone assays.

The aim of this study was to evaluate effects of alfalfa and fructooligosaccharides (FOS) on molting performance and bone parameters compared with the conventional feed withdrawal molting procedure. A total of 36 Single Comb White Leghorn hens (84 wk of age) were used for this experiment. The hens were divided into 6 treatment groups with 6 birds per treatment: pre-trial control (PC), full fed (FF), feed withdrawal (FW), 100% alfalfa (A100), A100 + 0.375% FOS (A100L), and A100 + 0.75% FOS (A100H). At the end of the 9-d molt period, hens were euthanized, and tibia and femurs were collected to evaluate bone qualities using dual-energy x-ray absorptiometry (DXA), Instron (Model 1011 Instron Universal Testing Machine, Instron Corp., Canton. MA), and conventional bone assays. Egg production was recorded during the molting period to evaluate first day out of production, and ovary was also collected to measure ovary weight. Alfalfa molting diets had comparable molting parameters, such as percentage of BW loss, ovary weight, and first day out of egg production, to the conventional feed withdrawal molting procedure, and FOS supplementation did not have any detrimental effects on molting performance. Conventional bone assay and DXA results suggest that hens lose a considerable amount of bone minerals during a molting period. The tibia and femur bone strengths of the FF, FW, A100, and A100L hens were significantly lower than the PC hens, whereas hens fed A100H had similar tibia bone breaking strength to that of the PC hens. The bone parameters measured by conventional assays, bone breaking strength measured by Instron, and bone density and mineral content measured by DXA were highly correlated to each other.

Ovarian laying hen follicular maturation and in vitro Salmonella internalization.

Transovarian transmission of paratyphoid Salmonella is well documented and occurs at a low incidence in chickens. However, the exact mechanism of follicular invasion is not well understood. The following study investigates the ability of Salmonella to invade ovarian follicles at different stages of follicular maturity in vitro. Ovarian follicles were collected from Leghorn hens and separated into three stages of maturity: (1) large yellow follicles or F follicles (LYF), (2) small yellow follicles (SYF), and (3) small white follicles (SWF). All follicles were incubated at 37 degrees C in RPMI 1640 medium. Follicles were incubated with 1 x 10(6) CFU/mL of Salmonella typhimurium and Salmonella enteritidis sensitive to gentamicin for 2 h. Samples were then removed from the bacterial culture, and placed in medium containing gentamicin sulfate for 5 h to kill any S. typhimurium or S. enteritidis, which had not invaded the follicular membrane. After the 5 h incubation, follicles were stomached in phosphate buffered saline. Serial dilutions were made of each follicle and viable S. typhimurium and S. enteritidis cells were enumerated on brilliant green agar. Two identical trials were conducted. Data suggest that Salmonella may differentially invade ovarian follicles depending on maturity of the follicle, and that SWF may be more susceptible to S. typhimurium and S. enteritidis invasion than either the SYF or the LYF.

Comparisons of molting diets on skeletal quality and eggshell parameters in hens at the end of the second egg-laying cycle.

A study was conducted to evaluate skeletal quality and eggshell parameters of molted hens at the end of the second laying cycle. Sixty Single Comb White Leghorn hens were used for this study. There were 2 controls and 4 molting treatments: full-fed control 1 (82 wk old; FF1), full-fed control 2 (122 wk old; FF2), feed withdrawal (FW), 100% alfalfa (A100), 90% alfalfa/10% layer ration (A90), and 70% alfalfa/30% layer ration (A70). At the end of the second laying cycle (approximately 122 wk of age), hens were euthanized by CO2. Tibia and femur were collected. There were no differences in bone parameters between FF1 and FF2 (P > 0.05) hens. There were no differences in bone parameters among the different molting dietary treatments (P > 0.05). In the eggshell parameters, the FF2 hens exhibited heavier egg weights than the FF1 (P < 0.05), whereas the percentage shell and egg production of the FF1 birds were significantly higher than those of the FF2 birds. Shell weights of the FW and A90 birds were significantly heavier than that of the A100. The correlation analysis showed that overall bone parameters were negatively correlated with eggshell parameters. Bone parameters were highly correlated with each other. Shell weight, percentage shell, and shell thickness were positively correlated with each other, whereas egg weight was negatively correlated with percentage shell. These results suggest that age of hens and molting dietary treatments influence egg parameters, and eggshell formation is closely related to bone metabolism in laying hens.