The nutritive value of normal and brown midrib-3 maize

Abstract

Summary: Normal and brown midrib-3 (bm₃) maize plants of three genotypes (Inra 188, Inra 240 and Inra 258) were sampled at three stages of maturity. Whole crop and plant components were analysed for in vitro digestible organic matter in the dry matter (DOMD) and the concentration of neutral detergent fibre, cellulose, hemicellulose, xylose, soluble sugars, starch and total nitrogen in the dry matter.The concentrations of total nitrogen, neutral detergent fibre, cellulose, hemicellulose and xylose were similar in both normal and bm₃ plants. Xylose was the main constituent sugar of hemicellulose forming 70–75% of the total hemicellulose. The higher concentration of soluble sugars and lower concentration of starch in the bm₃ plants was attributed to the later maturity of the bm₃ plants.The bm₃ gene significantly reduced lignin synthesis in the whole plant and plant components at all harvests. The mean concentration of lignin in the normal and bm₃ plants were 2·2 and 1·4%, respectively. The ferulic and p-coumaric acid concentrations in the bm₃ plants were 1·31 and 0·93 mg/g D.M. compared with 1·59 and 1·16 mg/g D.M. for the normal plants, respectively.The in vitro DOMD values for the bm₃ plants were significantly higher (P < 0.05) than their normal counterparts.