Chemical and physical properties and in vitro dry matter and starch digestion of eight sorghum grain hybrids and maize

Abstract

In vitro dry matter disappearance and gas production of eight divergent commercial sorghum grain hybrids and maize were measured. Sorghums included one bird resistant (BR) hybrid, plus seven non-bird resistant (non-BR) hybrid — two Yellow, two Cream, two Hetero-Yellow and one Red. Crude protein content of grains ranged from 9.5 to 10.5%. Sodium chloride soluble crude protein was greater ( P < 0.05) for maize than for sorghum grain hybrids, greater ( P < 0.05) for non-BR sorghum types than for BR, and greater ( P < 0.05) for Yellow than for Cream and Hetero-Yellow hybrids. In vitro dry matter disappearance was greater ( P < 0.05) for maize than for sorghum hybrids (51.8 vs. 39.6%), greater ( P < 0.01) for non-BR grains than for BR (41.4 vs. 26.9%), and greater ( P < 0.06) for Red than for Yellow, Cream and Hetero-Yellow hybrids (43.9 vs. 41.0%). Gas production after 24 h of incubation was greater ( P < 0.05) for sorghum hybrids than for maize (292.9 vs. 302.2 ml CO 2 per g starch) and greater ( P < 0.06) for Yellow, Cream and Hetero-Yellow hybrids than for Red (293.5 vs. 302.6). The magnitude of differences in gas production between sorghum hybrids and maize decreased with incubation time. The rate of gas production was greater ( P < 0.05) for sorghum grains than for maize (19.0 vs. 15.6% h −1), greater ( P < 0.01) for BR than for non-BR sorghum hybrids (22.8 vs. 18.4% h −1), greater ( P < 0.06) for Red than for Yellow, Cream and Hetero-Yellow hybrids (19.2 vs. 18.4% h −1), and greater ( P < 0.05) for Cream than for Hetero-Yellow hybrids (18.9 vs. 17.8% h −1). The rate of gas production also differed within endosperm color. Sorghum grain was more susceptible to degradation by amyloglucosidase, but was less susceptible to ruminal microbes than maize.