Relationship between fibre degradation kinetics and chemical composition of forages and by-products in ruminants

Abstract

This experiment was conducted to investigate the relationship between fibre degradation kinetics and chemical composition of forages and by-products using nylon bag technology. Four rumen fistulated goats fed a medium concentrate diet were used to measure degradation kinetics of dry matter (DM), neutral detergent fibre (NDF) and acid detergent fibre (ADF). Fourteen feed samples included 6 forage species (ryegrass, coronilla, clover, alfalfa, corn plant and wheat straw) and 2 by-product species (cottonseed hulls and corn cobs). Nylon bags were ruminally incubated for 0, 6, 12, 24, 48 and 72 h. NDF content of these feeds ranged from 35.7% to 93.8% of DM. Effective degradability of DM (DMD), NDF (NDFD) and ADF (ADFD) ranged from 6.0% to 76.3%, 4.2% to 52.5% and 3.2% to 41.1%, respectively. DMD, NDFD and ADFD were positively correlated with crude protein content (P < 0.05) but negatively with the content of NDF, ADF and lignin (P < 0.05). NDF content was the best feed composition for predicting DMD, NDFD and ADFD of forages and by-products. These results suggested that chemical analysis could give a satisfactory prediction towards degradable characteristics of fibrous feedstuffs in ruminants.