Technical note on a much simplified method for collecting ruminal fluid using a nylon paint strainer

Collection of ruminal fluid for in vitro experimentation has traditionally been accomplished by straining rumen digesta through multiple layers of cheesecloth or other cumbersome filtering materials, such as surgical gauze, nylon tissues or wire gauzes. We here report a comparison of the gross physical, fermentative and microbial characteristics of ruminal fluid collected by straining through cheesecloth or through a nylon mesh paint strainer that, because of its pouched shape, is conveniently filled with digesta thus making the collection and straining process much easier. Whether strained through cheesecloth or the nylon mesh strainer, ruminal fluid did not differ (P > 0.05) in dry matter, neutral or acid detergent fiber content or in concentrations of total culturable anaerobes. Total amounts (mM) of volatile fatty acid or ammonia produced after 24 h of incubation of cheesecloth- or nylon mesh-strained ruminal fluid with added tryptose, SigmaCell 50 or starch did not differ (P > 0.05) thus indicating that the microbial populations within the strained fluids possessed similar abilities to ferment these test substrates. Because the physical, fermentative and microbial characteristics of the nylon mesh- and cheesecloth-strained ruminal fluid were essentially equivalent, we conclude that the much easier to use nylon mesh strainers can be incorporated into a faster, more convenient ruminal fluid straining method.