Estimates of Dry Matter Digestibility Differences in Grain of Some Sorghum bicolor (L.) Moench Varieties1

Abstract

Grain of several varieties from the World Collection of Sorghum, Sorghum bicolor (L.) Moench, was analyzed for dry matter digestibility using the nylon‐bag method (NBDMD). Selected lines, parents, and hybrid combinations were analyzed using the NBDMD and in vitro dry matter digestibility (IVDMD) methods.All exotic sorghums selected for a high proportion of floury endosperm were more digestible than US varieties used as controls. White‐colored grains with more than 70% floury endosperm produced highest NBDMD values. Brown or purple grains containing high proportions of floury endosperm did not produce as high NBDMD values as white grains, but did produce higher NBDMD values than nonbrown grains of US varieties. Varieties with high NBDMD values as ground kernels were not always more digestible as whole kernels. NBDMD values of whole and ground nonbrown grain from hybrids was similar to the more digestible parent in the cross. Brownseeded hybrids tended to be intermediate between both parents when evaluated as ground grain. Whole kernel digestion showed nonbrown‐seeded hybrids to be intermediate between both parents in digestibility, but brownseeded hybrids were generally significantly lower in digestibility than the lowest parent.The modified Tilley‐Terry 2‐stage IVDMD method gave higher dry matter digestibility values than the 1‐stage IVDMD (rumen fluid alone) or NBDMD methods. NBDMD and IVDMD values for whole grain were highly correlated (r = .98). The 1‐stage and 2‐stage IVDMD percentages were significantly correlated for ground grain but IVDMD and NBDMD values for ground grain were not. Both the NBDMD and IVDMD methods gave significant correlations for whole vs. ground grain.