Particle Size Changes in Rumens of Cattle Grazing Kansas Flint Hills Range

Abstract

A ruminally fistulated Hereford steer and heifer grazing Kansas Flint Hills range were used with the objective of determining forage particle breakdown and distribution in different rumen sites over several hours post feeding during seasons of differing forage quality. During the first year, samples were taken after an overnight fast from 3 rumen sites and from feces early on the sample morning (AM sample). The cattle were fed and sampled again 12 hours later (PM sample). During year two, the cattle were sampled immediately as they came from the native pasture (PRE sample) in addition to the 2 other sample times. Samples were wet-sieved through a series of 5 screens to separate particle sizes. Material from each screen was dried, weighed and expressed as a percentage of the total of all screens. In the rumen, relative amounts of coarse particles generally decreased while amounts of smaller particles generally increased with advancing season. Forage maturity had similar effects on fecal particle sizes. Particles in the feces were more uniform in size than particles in the rumen.