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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.

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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

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.