Compositional variation amongst sorghum hybrids: Effect of kafirin concentration on metabolizable energy

Kafirins are stored proteins that negatively affect the nutritional quality of sorghum grain. Kafirin concentration and other chemical characteristics were determined in 12 sorghum hybrids and varied significantly, from 58% (HB1) to 42% (HB12) as percent total protein. Kafirin concentration correlated negatively with crude protein (CP) (−0.49), with acid detergent fiber (−0.40), apparent metabolizable energy (−0.61), and true metabolizable energy corrected for N (−0.63). HB12 was the hybrid with the lowest content of kafirins, amylose and tannins, and the highest content of apparent metabolizable energy. No differences were observed in the concentration of starch, but differences were found in apparent metabolizable energy (3325–2944 kcal kg−1) probably due to a greater availability of starch, related to differences in kafirin concentration.