Short communication: Effects of polyethylene glycol treatment on the chemical composition and in vitro dry matter degradability of Searsia lancea leaves

This study investigated the effects of incremental levels of polyethylene glycol (PEG) treatment on the chemical composition and in vitro dry matter degradability (IVDMD) of Searsia lancea leaves. Polyethylene glycol was sprayed onto S. lancea leaves at 0, 5, 10, 15, and 20 g/kg of dry matter (DM). Data were analysed using a one-way analysis of variance, while linear and quadratic responses were analysed using polynomial regression analysis. There were negative linear and quadratic effects on the crude protein (CP), neutral detergent fibre (NDF), total phenolic (TP), total tannin (TT), and condensed tannin (CT) concentrations in response to the incremental levels of PEG. Treatment with 20 g PEG/kg DM produced the lowest ether extract (EE), NDF, TP, TT, and CT concentrations. Magnesium showed a negative linear response to incremental levels of PEG, and treatment with 10 g PEG/kg DM produced the highest potassium, sodium, and sulphur concentrations. In vitro DM degradability at 36 hours showed a positive linear response to increasing levels of PEG, and 20 g PEG/kg DM resulted in the highest IVDMD. In conclusion, treating S. lancea leaves with incremental levels of PEG reduced the concentrations of CP, EE, NDF, TP, TT, and CT, while enhancing the IVDMD. Our results suggest that treatment with PEG at 20 g/kg may be most suitable for improving the nutritive value of S. lancea. (Submitted 2 March 2025; Accepted 17 September 2025; Published 13 October 2025)