Date of Award


Degree Type


Degree Name

Departmental Honors


Animal, Dairy, and Veterinary Sciences


This research investigated the toxic effect of manganese, in a reduced chemical state, on rumen microbial metabolism and growth. The reduced form of manganese is the soluble state found in subsurface waters and has a high red-ox potential. In the study, we investigated the effects of reduced manganese at varying concentrations, on rumen microbial ability to replicate and metabolize carbohydrates. The hypotheses that we tested were as follows: (1) reduced manganese decreases the rate of pH drop associated with rumen culture fermentation of a com based diet and (2) reduced manganese decreases the bacterial growth in rumen culture, as measured by bacterial DNA quantification. In this study, rumen culture material was obtained from a rumen canulated cow and dosed with test materials in randomly assigned flasks at 37° C. Cultures were replicated three times on different days. Test materials were dosed to result in the reduced form of manganese at concentrations of 0 ppm, 1.5 ppm, 3 ppm, 6 ppm, 12 ppm, 24 ppm, 48 ppm, and 96 ppm. Samples from each flask were obtained at 0 hr., 3 hr., 6 hr., 9 hr., and 12 hr. for measuring pH and at 0 hr., 3 hr., and 6 hr. for DNA. In these experiments, manganese inhibited the growth of the microbial population at > 3 ppm, but the rate of pH drop was not altered among the treatments used in this study.



Faculty Mentor

Jeffery O. Hall

Departmental Honors Advisor

Stan Allen