Chemical composition of forages in relation to their nutritive value

Abstract

A large number of samples of various strains/varieties of different legume and non-legume forages were analysed for different chemical constituents such as crude protein, neutral detergent fibre, total cell-contents, acid detergent fibre hemicellulose, cellulose, lignin and silica. Their in vitro dry matter and cell wall digestibilities were also determined. In general, non-legume forages contained appreciably higher amounts of NDF, ADF, hemicellulose, cellulose and silica and lesser amounts of crude protein, total cell contents and lignin when compared to legume forages. In vitro dry matter digestibility in legume forages was comparatively higher than in non-legume forages. Total cell wall digestibility, on the other hand, was notably higher in non-legume forages than in legume forages. In addition, certain tree leaves, important grass species and various straws/stovers were also analysed for the above chemical constituents. Grasses, in general, resembled non-legume forages in their chemical composition. Stage of maturity of the forage plant was shown to have a tremendous effect on its chemical composition. In general, with the advance of maturity, there was an increase in the concentrations of DM, ADF, NDF, hemicellulose, cellulose, lignin and silica and decrease in the concentrations of protein and total cell contents. The in vitro dry matter digestibility was also decreased with increasing maturity of the plant. The structural components such as NDF, ADF, hemicellulose, cellulose and lignin were negatively correlated (P<0.01) with in vitro dry matter digestibility of legumes and non-legumes. These constituents were included in computing the various prediction equations which could be utilized for determing the in vitro dry matter digestibility of forages and would be useful in initial screening of breeder's material.