Theses and Dissertations

Issuing Body

Mississippi State University


Willard, Scott T.

Committee Member

Rude, Brian J.

Committee Member

Vann, Rhonda C.

Date of Degree


Document Type

Graduate Thesis - Open Access


Animal Physiology

Degree Name

Master of Science (M.S.)


College of Agriculture and Life Sciences


Animal Physiology Program


Three different methods were developed to evaluate nutritional status: stable isotopes, near infra-red reflectance spectroscopy (NIRS), and microbial populations. In the first method, hair samples were collected, analyzed, stable isotope content greatly differed (P < 0.01) between pre- and post-weaning samples. The second method used NIRS spectral patterns and analyzed fecal samples, and a difference was found around 2100 to 2250 nm where diets containing milk showed a peak, and non-milk diets showed a plateau. Finally, the third method involved profiling microbial populations from fecal samples as calves experienced dietary shifts. Total anaerobes, enterics, and clostridium were different (P<0.05) from pre to post-weaning states. Total anaerobe samples differed (P < 0.005) from milk, milk-grain diets to grain and grain-hay diets. Total aerobes, streptococci, and clostridium samples differed (P <0.001) from the milk diet to the other diets. In summary, all three methods showed differences when comparing pre- to post-weaning states.