A Method for Estimating the Rate of Size Reduction, Passage and Fermentation of Ruminal Particles of Sheep

Abstract

This study attempted to develop a method for quantifying dynamics of particulate matter in the rumen of sheep fed on alfalfa hay at hourly intervals. The four compartments model for four size particulate fractions (large particle (LP):>5, 600, medium particle (MP): 5, 600-1, 180, small particle(SP): 1, 180-300, fine particle (FP): 300-47μm) in the rumen that has multiple pathways of size reduction, fermentation and passage was assumed. The respective rate constants were estimated by applying the in situ method and rare earth markers technique to each ruminal particulate fractions. The fermentation rate of each particulate fraction could be estimated from in situ disappearance curves. The rate of disappearance and the rate of size reduction of multiple pathways were able to be estimated by non-linear regression fitting to the theoretical equations from the dynamics model. The extent of fitting of the changes of markers in particulate fractions to the functions was enough to estimate the rate of disappearance and size reduction of ruminal particulate fractions. The rates of size reduction were 1.55 (LP→MP), 1.06 (LP→SP), 1.94 (LP→FF), 1.76 (MP→SP), 0.46 (MP→FP) and O.84%/h (SP→FP). The rates of fermentation were 1.47 (LP), 0.90 (MP), 0.08 (SP) and 1.19%/h (FP). The rates of passage were 1.82 (SP) and 3.94%/h (FP).