The Effects of Animal, Collection Time, and Interval on the Microbiota Structure, Metabolism, and Degradative Potential of Rumen Fluid Inoculum Collected by Esophageal Probe from Hay-Fed Cows

In vitro digestibility tests are essential for the evaluation of the nutritional value of forages and feeds but they need rumen fluid collected from animals as inoculum to be performed. However, it is well known that the degradative capacity of the rumen fluid can fluctuate depending on the animal and the time of collection, probably as a function of the rumen microbes’ populations. The enzymatic activity expressed by the microbes is expected to represent the rumen fluid’s degradative potential. The objectives of the present study were to investigate the effects of the animal and sampling time and interval on rumen microbes’ populations and degradative potential but also to investigate the relationship between different rumen characteristics. Rumen microbes differed by animal and week but not daytime. Rumen function indicators were not affected by the animal and only minor microbes’ metabolites showed variations during the day. The enzymatic activity was more variable depending on the animal and time, indicating the need to mix rumen fluids and replicate the analysis to obtain trustable results.