2018-09-042018-09-042018-082018-08August 201http://hdl.handle.net/2346/74487Certain probiotic lactic acid bacteria (LAB), also called Direct fed microbials (DFM), have beneficial effects in the gastrointestinal tract (GI) of pets through competitive exclusion of enteric-pathogen or by modulating the population of GI microflora, which can be monitored through the change in the load or shedding of microbial indicators such as: Generic E. coli, fecal coliforms, Entereobacteriaceae and Salmonella in fecal samples. Additionally, changes in the microbial populations can improve the overall gut health of the animal. The purpose of this study was to evaluate the impact of various combinations of probiotics including Lactobacillus salivarius L28 in the indicators during feeding. A total of 47 apparently healthy and domesticated dogs from various households within Lubbock County of Texas were randomly assigned to each of the 4 feeding groups; i) Control (without probiotics); ii) L28 iii) L28 and commercial probiotics and iv) commercial probiotics. These dogs differed in breed, gender, and age. During the adjustment phase, the kibble without probiotics was fed to every dogs for 7 days irrespective of the groups assigned. On the 8th day (Day 0 of the treatment phase) the three probiotic groups were given their respective treatment food, whereas the control group was continuously fed with the non-probiotic kibble. The group fed with L28 alone or the combined probiotics (L28 + commercial probiotics) received the L28 at a dose of 106 CFU/dog/day, based on average consumption. Fecal samples from each dog were aseptically collected and subjected to microbial enumeration on days 3, 2 and 1 before feeding probiotics (to generate a baseline of the microbial indicators), and on day 5, 10, 20 and 40 of the treatment phase (to assess the impact of probiotics). Simultaneously, the fecal were screened for Salmonella with Real- Time BAX kit followed by selective enrichment, selective plating, and agglutination test for confirmation, before and during treatment. The group fed with combination of L28 and commercial probiotics showed a higher reduction in the fecal population of Generic E. coli, fecal coliforms, total-coliforms and, Entereobacteriaceae compared to the groups fed with the non-probiotic kibble, L28 or the commercial probiotics. Similarly, the group fed with combined probiotics had the highest proportion of dogs with greater than 1-log cycle reduction in the four microbial indicators. Like the control group, the group fed with Lactobacillus salivarius L28 alone or the commercial probiotics did not exhibit a significant reduction (p<0.05) in the microbial indicators over-time. Whereas, the group treated with combination of L28 and commercial probiotics at the given dose of L28 showed a significant reduction (P<0.05) in the fecal population of the indicators compared to baseline. However, the efficacy of L28 + commercial probiotics to reduce the indicators in the fecal samples depended on the duration of the feeding. Similarly, the effect of the supplement and its duration varied between the subjects in the group. A significant reduction (P<0.05) in all the indicators in the group was observed after 20 days of feeding. There was a rare presence of Salmonella in the dogs under study during baseline. The reduction in microbial indicators suggests the potential of L28 + commercial probiotics to reduce/control the growth of enteric-pathogens and modulate the balance of GI micro-flora towards healthier ones. This microbial shift could boost the gut health of the animal. Thus, L28 can be a promising component of the commercial probiotics formulation to add better functionality to kibbles for maintaining or improving GI health of pets and lowering incidence of zoonotic diseases in humans.application/pdfengDirect-fed microbialProbioticsIndicatorsLactobacillus salivarius L28Thesis2018-09-04Restricted until September 2019. For access, request a copy.