Evaluating the Use of Stable Isotopes, Nirs, and Microbial Populations to Detect Dietary Changes in Dairy Calves
Cooley, Kathryn Marie
AdvisorWillard, Scott T.
CommitteeRude, Brian J.
Vann, Rhonda C.
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.