Physical characteristics of reticular content in the bovine and consequences on reticular outflow.

Reticular content was sampled in cows before and 2 and 5 hours after they were fed various forages. Dry matter, particle size distribution, pH, osmotic pressure and viscosity of the liquid phase were measured. Consistency was also evaluated using purpose-built apparatus. The contents were fractionated by vertical distribution under gravity and by intermittent flow through an orifice into fractions containing different particle concentrations, to model reticular retention of large particles in rumen outflow. Retention occurs as a result of a combination of flotation carrying large particles back into the rumen, and filtration which prevents them leaving it. These processes are particularly effective after feeding, and with poor hay, and so help prolong fermentation time. The consistency of reticular content is relatively stable; it may be autoregulated by adjustment of feeding parameters in response to sensory receptor signals.