The Physical Characteristics of Digesta

Abstract

We examine the physics of flow and mixing in the particulate suspensions that constitute digesta. We examine how this changes with alterations in the relative volumes of solid and liquid components as digesta transits the digestive tract. The effects of the size and shape of the component particles and of interactions between them on the rheological properties of fluid and semisolid digesta are discussed. The effects of gas bubbles and oil droplets on particulate systems are also discussed. The mechanics that may lead to relative movement between the liquid and solid phases of digesta or between large and small component particles are examined. Hence the effects of particle buoyancy and the mechanisms of particle caking and subsequent filtration and expression of the liquid phase are explored. The chapter concludes with a brief review of what is known regarding the contribution of biofilms on particles to the physical characteristics of digesta.