Previous research has documented shifts in microbial hindgut populations resulting from dietary starch inclusion, and recent evidence indicates only 30% of equine cecal contents has been cultured successfully. Next generation sequencing (NGS) techniques allows detection of new species previously undetected. Therefore, the objective of this study was to determine community profiles equine cecal microbiota in response to abrupt dietary starch inclusion. Seven cecally cannulated Quarter horse geldings (497 to 580 kg) were utilized in a crossover design with two 28 d periods and a 28 d washout between each. Horses were randomly assigned to dietary treatments consisting of commercial concentrate offered individually at either 0.6% (LS) or 1.2% BW (HS; as fed) daily divided into 2 meals at 12 h intervals. Prior to start of each period horses were allowed ad libitum access to coastal bermudagrass (Cynodon dactylon) hay and concentrate was fed on d 1 with no adaptation. Samples of cecal fluid were collected on d 1 prior to 0 h and 3, 6, 9, and 12 h post morning meal and on d 1, 2, 3, and 7 at 6 h post morning meal. Cecal pH was determined immediately and a samples of cecal fluid were stored. Genomic DNA was extracted and the V4-V6 segment of 16s rRNA gene was PCR amplified using universal Eubacterial primers 530Fand 1100R and sequenced on the Roche 454 FLX platform. The reads were denoised, chimera checked, and Operational Taxonomic Units (OTUs) were identified using the reference Ribosomal Database Project 16S rRNA dataset. Data were analyzed using PROC MIXED procedure of SAS. Bacterial phyla were largely unaffected by dietary treatment for the first 12 h after the initial concentrate meal except for Verrucomicrobia which was greater in LS horses (P ≤ 0.04). Regardless of treatment, Bacteriodetes increased (P ≤ 0.02) over the first 12 h following initial addition of dietary starch. Adaptation to dietary treatments over 7 d resulted in decreased numbers of Tenericutes (P ≤ 0.07) in HS horses compared to LS. Cecal environment and microbial populations were altered after abrupt and long term exposure to dietary starch.

No description available.

The development of the intestine and early establishment of commensal bacteria is important for rapid growth and enteric disease resistance of the modern broiler. Three studies measured the impact of yeast derivatives in diets of broilers. The objective of the first study was to determine if yeast products alone or in combination effected performance or gut morphology of broilers during a mild coccidia challenge. Day-old Cobb 500 chicks were placed in floor pens on litter seeded with coccidia and fed diets with or without yeast products. The objectives of the second and third studies were to 1) evaluate the effect of feeding cecal droppings collected from heavy (HW) or low weight (LW) broilers on performance and 2) to determine if dietary supplementation with yeast derivatives would effect growth and gut morphology in broilers fed the cecal droppings from HW or LW populations. Cobb 500 chicks were divided into two groups (HW or LW microflora; n=1400/group) and given access to the cecal droppings for a period of 48 hours then given 1 of 4 diets. The results from the studies showed that in a challenge setting, yeast products were not detrimental to growth. Inclusion of single yeast derivative or nucleotides was more beneficial than combination of these products for intestinal morphology. Cecal droppings from HW vs. LW birds did not have an effect on performance of birds. However, interactions of cecal dropping source and diet did affect intestinal morphology. / Master of Science

Thesis (Ph.D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (April 25, 2007) Vita. Includes bibliographical references.

Eight cecally cannulated Quarter Horse geldings were utilized in a crossover design with two 28 d periods with a 21 d washout period between. Horses were adapted to dietary treatments from d 1 to 19, dry matter intake was determined from d 20 to 24, and cecal fluid was collected on d 28. Horses were paired by age and body weight (BW) and randomly assigned to treatment. Treatments consisted of housing horses individually in stalls or group housed in a dry lot pen. Regardless of treatment, all horses were individually fed a pelleted concentrate at 1% BW (as fed) offered twice daily 12 h apart. All horses had ad libitum access to coastal bermudagrass hay. Hay was offered to stalled horses initially at 2% BW (as fed) then adjusted based on 120% of a previous 3 d average of voluntary intake. A dual marker system was utilized for estimation of voluntary intake in all horses using titanium dioxide (TiO2) as the external marker and acid detergent insoluble ash (ADIA) as the internal marker. Cecal samples were collected 4-h after the morning meal and immediately analyzed for pH. Samples were transported to the USDA/ARS laboratory to enumerate total anaerobic bacteria and lactic acid bacteria, and to determine methane and ammonia activity. Cecal pH was influenced by housing (P = 0.02) with group housed horses having lower cecal pH values when compared to stalled horses (6.52 +/- 0.04 and 6.69 +/- 0.04, respectively). The cecal pH values of this study are similar to other reported values when feeding similar diets (5). Populations of cecal total anaerobic bacteria and lactobacillus were not influenced by housing (P >= 0.21). Treatments did not affect the production of acetate, propionate, or butyrate (P >= 0.15). Additionally, methane and ammonia production were not affected by treatments (P >= 0.17). Forage intake was greater for group housed horses (P = 0.04) than stalled (8.47 +/- 0.89 kg DM/d and 5.17 +/- 0.89 kg DM/d, respectively). In conclusion, confinement housing did not greatly influence the cecal environment of a horse when similar diets were offered.

Salmonellosis is one of the most important bacterial food borne illnesses worldwide. Among the many Salmonella serotypes, Typhimurium is the most commonly implicated serotype in human disease in the United States. A major source of infection for humans is consumption of chicken or egg products that have been contaminated with S. Typhimurium. The breadth of knowledge regarding colonization and persistence factors in the chicken is small when compared to our knowledge of factors that are important for these processes in other species used in Salmonella research, such as cattle and mice. Defining the factors important for these processes in the chick is the first step in decreasing the transmission of Salmonella between animal and human hosts. In this work, we developed a chicken model to identify and study intestinal colonization and persistence factors of Salmonella enterica serovar Typhimurium. We studied the degree of enteric and systemic colonization of wild type S. Typhimurium ATCC14028, one of the most widely studied Typhimurium isolates, in White Leghorn chicks and in Salmonella-resistant CBA/J mice during infection. Furthermore, we determined the distribution of wild type S. Typhimurium and a SPI-1 mutant (invA) during competitive infection in the cecum of 1-week-old chicks and 8-week-old mice. Cell associated, intracellular and luminal distributions of these strains in the cecum were analyzed as total counts in each compartment and also as a competitive index. Localization of S. Typhimurium ATCC14028 and the role of SPI-1 in colonization are well studied in murine models of infection, but comparative infection in chicks with the same strain has not been undertaken previously. We show that the cecal contents are the major site for recovery of S. Typhimurium in the cecum of 1-week-old chicks and Salmonella-resistant mice. We also show that while SPI-1 is important for successful infection in the murine model, it is important only for cell association in the cecum of 1-week-old chicks. Finally, we found that in chicks infected at 1 week of age, bacterial counts in the feces do not reflect those seen in the cecum as they do in mice.

Master of Science / Department of Animal Sciences and Industry / Teresa L. Douthit / Abruptly increasing concentrate in the ration of horses results in altered cecal dynamics which can culminate in digestive distress. Nine Quarter horses previously fitted with cecal cannulae were utilized for 3 consecutive 22-d experiments, each separated by 2 d of rest. During Exp. 1 and 2 horses were acclimated to the same ration for the initial 21 d of each period, followed by a concentrate challenge on d 22. The acclimation ration consisted of a morning meal of 0.5% BW concentrate (Omolene 200, Purina Animal Nutrition, LLC, Gray Summit, MO) fed with 1.5% BW prairie grass hay divided evenly between a morning and evening meal. On d 22 of Exp. 1, horses were fed a morning meal consisting solely of 1.0% BW concentrate while 1.25% BW concentrate was fed on d 22 of Exp. 2. Cecal samples were obtained through cecal cannulae from d 19 to 22 of each experiment every 4 h for h 24 following the morning meal each day. Cecal pH during Exp. 1 was recorded and decreased at h 12 following the concentrate meal on d 22 in comparison to cecal pH at h 12 on d 19 to 21 (P = 0.009). During Exp. 2 cecal pH increased at h 4 (P = 0.02) and decreased at h 12 and 20 (P < 0.0001) following this oncentrate challenge compared to cecal pH recorded at the same time points during the acclimation period. Experiment 3 differed from that of Exp. 2 only in the respect that during the acclimation period horses were fed, in addition to the acclimation ration, either a proprietary supplement (n = 5) or a placebo (n = 5). Cecal samples from d 19 to 22 were analyzed for pH, concentration of lactate, and concentration of VFA. Horses consuming the supplement had increased cecal pH at h 4 (P = 0.009), concurrently decreased cecal lactate (P = 0.02), increased ratio of (acetate+butyrate)/propionate at h 8 and 16 (P ≤ 0.006), and decreased VFA concentration at h 24 (P ≤ 0.05) compared to horses in the control group following the concentrate challenge.

Master of Science / Animal Sciences and Industry / Teresa L. Douthit / Abrupt dietary changes increase a horse’s risk for developing gastrointestinal diseases, such as colic or laminitis. Understanding the impact of various feeds and feeding practices on feeding behavior and gastrointestinal function creates a whole-animal perspective that allows for a more holistic interpretation of the effects of abrupt dietary changes on the hindgut environment. Unfortunately, few reports exist that have examined the effects of abrupt dietary changes in the horse. This study was designed to determine the effects of various abrupt dietary changes on the hindgut environment. In 4 sequential experiments, horses were exposed to an abrupt change from a baseline ration to a complete pelleted diet, an abrupt change from a baseline ration to a 100% grass hay diet, an abrupt change from a prairie hay ration to an alfalfa hay ration, and an abrupt change from a baseline ration to a large concentrate meal. These dietary challenges were chosen to mimic real-world scenarios that horse owners are likely to encounter. These experiments were arranged into a longitudinal trial in which the effects of the abrupt dietary change on cecal and fecal pH, total lactate and volatile fatty acid (VFA) concentrations, cecal lactate-utilizing bacterial populations, and fecal dry matter (DM) were compared to values obtained while horses were consuming the baseline diet. In the first experiment, decreased cecal (P ˂ 0.0001) and fecal (P ˂ 0.0001) pH values combined with increased cecal total lactate (P ˂ 0.001) and fecal VFA concentrations (P ˂ 0.0001) indicate that the abrupt change to a complete pelleted diet disrupted the stability of the hindgut environment. Because cecal pH values were below 6.0, this dietary challenge may be significant enough to elicit subclinical fermentative acidosis and, thereby, increase colic risk. The dietary change to grass hay had little impact on the hindgut environment, as pH, total lactate, and VFA concentrations remained stable (P ≥ 0.05). In general, horses may well tolerate an abrupt increase in the fibrous component of the diet and the elimination of concentrate, a dietary shift that presents a more natural diet to the horse. The abrupt change to alfalfa hay elicited alterations in cecal pH (P ˂ 0.01), total lactate (P ˂ 0.0001) and VFA concentrations (P ˂ 0.05), and lactate-utilizing bacterial populations; however, fecal parameters varied little in response to the dietary change (P ≥ 0.05), indicating that the distal hindgut may be more tolerant to abrupt changes in forage sources than the cecal environment. Here, the potentially adverse shifts in cecal parameters indicate that an abrupt change in hay type and quality alters the fermentative environment of the proximal hindgut and may increase a horse’s risk for gastrointestinal disease. Similarly, the abrupt introduction of a large concentrate meal elicited a decrease in cecal pH (P ˂ 0.005) along with increases in total lactate (P ˂ 0.001) and VFA concentrations (P ˂ 0.05) in the cecum that were consistent with previously reported experiments in which horses were presented with large increases in dietary concentrates. Notable shifts in lactate-utilizing bacterial growth curves were also observed. Overall, these results provide evidence of environmental alterations in the equine hindgut that support epidemiological reports that associate abrupt changes in the amount and type of concentrate, hay type and quality, and forage:concentrate ratio with increased risk for gastrointestinal disease in horses.

Thesis (Ph. D.)--University of Missouri--Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 100-112). Also issued on the Internet.

Thesis (Ph. D.)--University of Missouri--Columbia, 2004. / "May 2004." Typescript. Vita. Includes bibliographical references (leaves 100-112). Also issued on the Internet.