Urea nitrogen induces changes in rumen microbial and host metabolic profiles in dairy cows — D.Jin — Livestock Science (microbiomedigest.com)
For example, based on the isotope ratios they detected in cow rumen, they calculated that this methane formed at 400 degrees Celsius — impossible, as cow stomachs are typically about 40 C. (sciencedaily.com)
According to the AAFCO definition, meat meal is a «rendered product from mammal tissues, exclusive of any added blood, hair, hoof, horn, hide trimmings, manure, stomach and rumen contents except in such amounts as may occur unavoidably in good processing practices.» (topdogtips.com)