Aim of this study was to select environmental E. coli isolates that produced colicins against the swine pathogen E. coli K88+. In initial evaluation using a modified plate method with 18 colicinogenic E. coli constructs, colicins E3, E4, E5, E9, Ia, K and N were found to possess inhibitory activity against 12 ETEC K88+ strains. A total of 463 environmental isolates from cattle rumen, cattle feces, pig feces and hog manure-amended soil were screened for colicin production by a modified plate test. Further, colicinogenic isolates were screened for five toxin genes LT, STa, STb, VT1 and VT2 as well as K88 (F4) fimbriae using PCR reactions. Fourteen non-pathogenic isolates were subjected to characterization of colicin genes by PCR using 9 new primer sequences, antibiotic susceptibilities and substrate utilization. Two potential probiotic strains of E. coli, UM-2 and UM-7 which produced colicins that could utilize potato starch and inulin were selected for in-vitro competition with E. coli K88+ strain 2-12. In vitro competition between the synbiotics and E. coli K88+ revealed inhibition of E. coli K88+. Based on the present in vitro studies it could be concluded that carefully selected potential synbiotics should be further studied for their role in protecting piglets from post-weaning diarrhea without antibiotics.

Aim of this study was to select environmental E. coli isolates that produced colicins against the swine pathogen E. coli K88+. In initial evaluation using a modified plate method with 18 colicinogenic E. coli constructs, colicins E3, E4, E5, E9, Ia, K and N were found to possess inhibitory activity against 12 ETEC K88+ strains. A total of 463 environmental isolates from cattle rumen, cattle feces, pig feces and hog manure-amended soil were screened for colicin production by a modified plate test. Further, colicinogenic isolates were screened for five toxin genes LT, STa, STb, VT1 and VT2 as well as K88 (F4) fimbriae using PCR reactions. Fourteen non-pathogenic isolates were subjected to characterization of colicin genes by PCR using 9 new primer sequences, antibiotic susceptibilities and substrate utilization. Two potential probiotic strains of E. coli, UM-2 and UM-7 which produced colicins that could utilize potato starch and inulin were selected for in-vitro competition with E. coli K88+ strain 2-12. In vitro competition between the synbiotics and E. coli K88+ revealed inhibition of E. coli K88+. Based on the present in vitro studies it could be concluded that carefully selected potential synbiotics should be further studied for their role in protecting piglets from post-weaning diarrhea without antibiotics.

Master of Science / Department of Animal Sciences and Industry / James M. Lattimer / Three experiments were conducted to determine the impact of novel probiotic (NP) supplementation in monogastric livestock and poultry. Experiment 1 evaluated effects of the probiotic on growth performance and cecal parameters in broiler chickens (n = 2520). Birds in treatment groups 1 and 2 were administered NP culture as either an oral gavage (OG) or an aerosolized mist (AM), respectively. Treatment group 3 served as a negative control (C). Growth performance and feed efficiency (FE) were unaffected by treatment (P > 0.10). Cecal pH was reduced in AM and OG birds compared to C (P < 0.05). This novel probiotic is most effective in altering cecal VFA profile before d 21 post-administration, after which no differences in VFA concentrations were detected between treatments. Reduction in cecal pH in response to NP indicates potential application of this probiotic as an acidifier, commonly used in poultry production as an antibiotic alternative. Experiment 2 was a swine performance study conducted to determine effects of treating sows or piglets or both with an oral gavage of NP. Factor 1 consisted of administration of NP oral gavage administered to sows or a negative control (n = 28). Factor 2 consisted of either a negative control or oral gavage of NP administered to litters of piglets shortly after birth and at weaning. Sow weight loss during lactation was unaffected by treatment (P > 0.10). Feed intake upon introduction to the nursery was greater in piglets that received NP directly than those that did not (P < 0.05). Large intestinal fermentation in both sows and piglets was affected by NP administration. Fecal VFA concentrations tended to be greater in animals that received NP either indirectly through the sow or directly via oral gavage (P < 0.05). Direct supplementation of piglets with NP is more effective in altering fermentation after d 21 than indirect administration, as VFA concentrations in piglets that received NP indirectly are similar to the control by d 28. Butyrate concentrations were greater in piglets that received NP; this VFA is important in prevention of intestinal atrophy and recovery from physiological stress of weaning. Experiment 3 examined effects of NP administered as either an oral drench (OD) or a lyophilized powder (LP) on equine cecal fermentation compared to a negative control (NC). Cecally cannulated horses (n = 8) were transitioned to a 1:1 roughage to concentrate diet over a period of 5 d. Cecal pH was greater than NC in OD and LP horses on d 5 and d 7, respectively (P < 0.10). Acetate:propionate ratio, valerate, and caproate concentrations also were greater in LP horses than NC on d 7 (P < 0.05). This may indicate improved gut health and fiber digestion in supplemented horses. The novel probiotic used in these studies is able to effectively alter large intestinal fermentation in monogastric species and may have potential to improve gut health and performance of these species.

Probiotics are an alternative to increase broiler productivity and flock health. For this reason, the objective of the first study was to evaluate commercially available Bacillus spp. based probiotic products on their ability to reduce Salmonella Heidelberg, in vitro. Results showed that most products reduced the lower concentrations of S. Heidelberg and maintained a reduction for up to 8 h. The second study was conducted to determine if bacterial colonization occurred in a broiler chick after in ovo injection. Using bioluminescence, it was demonstrated that bacteria could migrate and colonize the embryo within 2 h after in ovo injection into the amniotic fluid. The results of these studies demonstrated that probiotics could reduce pathogenic microorganisms and can potentially have a positive impact on the chick before it even hatches and is placed in a broiler house.

The primary objectives of the following experiments were to: 1) determine the impact of a directed microbial (DFM) blend on digestibility and microbial populations on horses fed low (LQ) and high (HQ) quality hay, 2) evaluate the differences in diet digestibility, microbial populations, and blood metabolites due to DFM supplementation to the exercising horse, 3) assess the impact of short-chain fructooligosaccharide (scFOS) supplementation on digestibility and the fecal microbial ecosystem in senior (SR) vs. mature (MA) horses, and 4) determine the relationship between insulin dysregulation (ID) and morphometric neck measurements (MNM) in the non-obese stock-type horse. Results indicated that: 1) Supplementation with DFM tended to be beneficial in enhancing CP digestibility. Feeding CP beyond requirements may contribute to excess excretion of Escherichia coli (EC) in HQ which was supported by 16S rRNA analysis. Differences in the fecal microbial ecosystem were detected between LQ and HQ. The phylum Saccharibacteria was identified in both hay qualities even though it has been lightly reported in equine literature. 2) Supplementing DFM to moderately exercised horses tended to enhance DM and ADF digestibility but there was no evidence of a dietary modulation to the fecal bacteria isolated. 3) No differences were found between MA and SR when fed scFOSded ration balancer which indicates that scFOS may help mitigate decreases in digestibility experienced by SR. Senior horses had less diversity in their fecal bacterial population, which may help explain why SR are more prone to ailments such as colic and impaired immune function. 4) Obesity is an important genetic factor for ID however it should not be the only determining factor, as ID can occur in non-obese individuals. One individual out of 62 tested horses was identified as ID. Morphometric neck measurements (MNM) may help pinpoint horses that are at a greater risk for ID, but more research is needed to validate MNM in both obese and non-obese stock-type horses. There were correlations between glucose sampled before an oral sugar test (OST) and insulin post-OST but a fasting OST would still be recommended in assessing ID.

The effects of dietary antimicrobial removal and Bacillus subtilis supplementation on the growth and intestinal health of male broilers were investigated. Birds were fed either a control, antimicrobial, or a B. subtilis probiotic diet at different feeding phases. Birds were challenged with a 10 × dose of a coccidiosis vaccine. Supplementation of B. subtilis in for antimicrobials in the late grower and early finisher phases improved growth similar to birds fed antimicrobials until withdrawal, while antimicrobial removal without B. subtilis supplementation in those periods hindered growth. The improved growth suggests that the probiotic was able to alleviate the stress of the challenge compared to antimicrobial removal. Processing yields were improved with antimicrobial removal and B. subtilis supplementation in late grower and early finisher phase. Intestinal health was improved with lower intestinal lesions when antimicrobial were removed and B. subtilis supplemented suggesting the reduction of Eimeria species from colonizing the intestine.

Celiac disease (CD) is an autoimmune disorder that affects approximately 1% of the population [55]. CD is characterized by intestinal villus atrophy after consumption of gluten from wheat, barley, or rye. Patients with CD often experience abdominal pain, diarrhea, malnutrition, fatigue, and a failure to thrive. There is currently no treatment for CD. Patients must live on a strict lifelong exclusion of dietary gluten. Due to the high content of gluten in western diets and poor labeling of gluten content, adherence to a gluten free diet (GFD) is difficult [15].Nearly all the enzymes that can digest the gluten peptide are sensitive to the stomach's low pH . As a result, dietary supplementation with enzymes to digest gluten has yet to produce a viable alternative treatment to a GFD. We propose to use a resident microbe of the human intestinal tract to express a peptidase to digest the immunoreactive gluten fragments. The bacteria, L. reuteri, will colonize the host's intestines and digest the gluten peptides before causing an autoimmune response. To accomplish this task, this thesis describes a food grade, plasmid based system to integrate genes into the genome of L. reuteri. The plasmid system utilizes an origin of replication that requires a protein, RepA, to propagate itself. A helper plasmid provides the RepA protein in trans to an integration plasmid that cannot provide RepA to itself. The integration plasmid carries a homologous region to the genome of L. reuteri allowing for targeted genomic integration. The integration plasmid will not replicate on its own, and will be integrated into the genome if the helper plasmid is absent. To select for these genomic integrants the integration plasmid expresses an erythromycin resistance marker. Using the Cre/Lox system the antibiotic resistance will be removed from the bacterial genome to re-establish the L. reuteri's food grade status. This thesis describes the construction and verification of the above mentioned plasmid tool kit containing the helper, integration, and Cre expression plasmids to integrate genes into the L. reuteri genome.

The use of antibiotics as growth promotors in the food animal industry has led to the generation of antibiotic resistant microorganisms, which are a major health risk to humans. Therefore, bans and limitations, including the FDA’s veterinary feed directive, have been placed on the use of antibiotics as growth promotors, and there has been a push to find an adequate alternative. In the laying hen, probiotics and/or prebiotics have shown promise as they help promote the colonization of beneficial bacteria in the GI tract of the host, increase feed efficiency, increase egg production, and provide protection against pathogenic bacteria. In this feeding trial, Leghorn HyLine W36 hens were fed diets supplemented with either 0.05% IMW50(prebiotic), 0.05% CALSPORIN (probiotic), 0.05% IMW50 and 0.05% CALSPORIN, or a control diet with no prebiotic or probiotic additive. The birds were maintained on this diet from 1 day to 66 weeks of age, over which time feed intake and egg production was measured. From 37 to 65 weeks of age, every 3-5 weeks, egg quality was evaluated through specific gravity, egg weight, albumen height, and eggshell breaking force measurements. At 6, 16, 32, and 64 weeks of age, the microbiota population in the ileal digesta was evaluated using T-RFLP analysis methods. Then at 64 weeks of age, splenic IFN-γ, IL-6, IL-10, and IL-12 expression was measured by RT-qPCR. Unexpectedly, fluctuations in feed disappearance were observed, potentially linked to factors such as changes in diet type, temperature variations, feed wastage, or a technical error. Birds on CALSPORIN-containing diets showed resilience and maintained egg production during a decline in feed disappearance, suggesting enhanced capabilities in digesting larger particle sizes. However, there were trade-offs, as egg quality parameters slightly decreased in supplemented diets. CALSPORIN alone showed a promising effect on survival probability. Microbial diversity in the ileum increased with CALSPORIN, but the IMW50 alone led dysbiosis, possibly impacting infection resistance. Additionally, the combined supplementation of IMW50 and CALSPORIN may have introduced a disruption in immunological homeostasis.

No description available.

Improving growth, lowering mortality rates, and having a faster turnaround to harvest is essential for the future of commercial aquaculture. The primary goal of this study was to determine if introducing a single strain probiotic Lactobacillus rhamnosus IMC 501 into the feed regimen of a commercially important aquaculture freshwater fish, Mozambique tilapia (Oreochromis mossambicus), would decrease mortality; change metabolic rates; and increase tissue wet mass (MW), standard length, growth rate and feed conversion rate (FCRs). IMC501 was added to the fishmeal in four increasing concentrations and compared to a control without probiotics. Results from two-way ANOVAs showed that both treatment levels and elapsed time had a significant effect on both mean standard length and wet mass; in the latter case, time points and treatments interacted with one another, showing that tilapia grew best with a moderate level of probiotics present. The growth benefits of probiotics continued for months after the initial treatments. Oxygen consumption (metabolic rate) was measured using closed respirometry and resulted in recording the first values for juvenile tilapia treated with probiotics. For oxygen consumption, there were significant treatment and time effects with significant interactions, indicating that metabolism increased with probiotics once the dosage exceeded three times the industry level. These results are consistent with the observed increases in mass, length and growth rates. These results demonstrate the importance of conducting dose-response experiments in order to determine the most effective concentration of probiotics in juvenile freshwater fish. Importantly, probiotics at the right concentration increase metabolic rates and can positively influence tilapia growth, which is of interest for the optimization of Mozambique tilapia production in aquaculture.