Leaf chemical analysis

Leaf material from each of the browsed species was collected for chemical analysis. The leaf samples were taken from five unbrowsed trees (below 1.5 m above ground) per species (A. nilotica, A. karroo, D. cinerea, S. tenuinervis and Z. mucronata). The leaf samples were air dried prior to oven drying at 60°C for 48 h. The leaf samples were then milled to pass through a 1.0 mm mesh using a Wiley mill and then analysed for CP, fibre (acid and neutral detergent fibre), TP and CT concentration. Each chemical component was expressed as a percent of the sample dry matter. Nitrogen (N) concentration was determined using the Kjeldahl method [37] and converted to crude protein (N x 6.25). Neutral detergent fibre and ADF were determined according to van Soest et al. [38] using the ANKOM Technology. Phenolic compounds were extracted and TP and CT concentrations determined. Total phenolic concentration was determined using the Folin-Ciocalteau method [39]. Gallic acid (0.5mg/ml) was used as a standard and the TP concentration was expressed as gallic acid equivalents (GAE). Condensed tannins concentration was determined using the butanol-HCl method and expressed as leucocyanidin equivalent [38]. Dry matter digestibility was estimated using the formula: DMD% = 83.58–0.824 ADF % + 2.626 N% [40].