Characteristics of the Rate and Extent of Fiber Degradability of Feedstuffs Common to the Pacific Northwest

Abstract

Seventeen forage samples and 23 grain and by-product feed samples were collected through western Washington State. The chemical compositions of DM, N, NDF, and ADF were determined. The rate and extent of DM and NDF degradation of feedstuffs, and the ruminal fill of DM and NDF of feedstuffs were determined from the in situ measurement. Correlations among variables were evaluated. Early-cut grass silage (a mixture of orchardgrass, ryegrass, and a small proportion of clovers) had a greater rate and extent of NDF degradation than late-cut grass silage. Pooled grass silage had a greater rate and extent of NDF degradation than com silage or sunflower+com silage and alfalfa hay was intermediate. The rank of forages based on mean ruminal fill of NDF was as follows: com silage or sunflower+com silage > grass silage > alfalfa hay > green chop. Commercial grains and by-product feeds had larger variations in terms of the rate and extent of NDF degradation. The extent of DM and NDF degradation (degraded DM and NDF in the total percentage of DM and NDF) was inversely correlated with the percentage of NDF or ADF in forages, grains, or by-product feeds. The concept of half-life of NDF in the rumen was introduced to quantify degradation of NDF in the rumen.