Mississippi State University
Cavinder, Clay A.
Paz, Henry A.
Rude, Brian J.
Date of Degree
Original embargo terms
Dissertation - Open Access
Agricultural Science (Animal and Dairy Science)
Doctor of Philosophy
College of Agriculture and Life Sciences
Department of Animal and Dairy Sciences
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.
Heaton, Courtney, "Effect of pro- and prebiotics on the apparent digestibility of nutrients and identification of fecal bacterial isolatew in the sedentary and exercising horse" (2019). Theses and Dissertations. 1680.