Bromatological and histological features of native African grasses under grazing in Brazilian semi-arid rangelands

Abstract

This study evaluated the bromatological and histological features of native African grasses under grazing in Brazilian semi-arid rangelands. An experimental grid design was used in a randomised sampling method for four replicate samples of three African grasses. The grasses evaluated were: Cenchrus ciliaris L., Digitaria pentzii Stent. and Megathyrsus maximus (Jacq.). The bromatological and histological traits analysed included dry matter (DM), crude protein (CP), neutral detergent fibre corrected to ashes and protein (NDFap), lignin, mesophyll, vascular bundle, phloem, xylem, vascular sheath, sclerenchyma, bulliform cells, and the adaxial and abaxial epidermis. The type of grass and grazing cycle correlated with DM, NDF and lignin (p < 0.05), whereas CP was not affected by these factors (p > 0.05). Dry matter ranged between 128 and 304 g kg⁻¹; CP ranged between 90 and 167 g kg⁻¹; NDFap between 542 and 707 g kg⁻¹, and lignin between 10 and 40 g kg⁻¹. The proportion of xylem (8.4%), vascular sheath (30.5%) and total vascular bundles (38.1%) were greater in M. maximus (p < 0.05). The percentage of sclerenchyma did not differ between species (p > 0.05). Digitaria pentzii and C. ciliaris had a greater proportion of mesophyll than M. maximus (p < 0.05). Of the three grasses analysed. Digitaria pentzii exhibited the highest forage quality, because it had the lowest concentration of fibre and lignin, with lower proportions of lignified tissues.