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Effect of Pre-treating Green Tea (Camellia sinensis) Powder with Graded Levels of Polyethylene Glycol on Chemical Composition and In-vitro Ruminal Fermentation

Matabane, A.N.¹, Setou, B.A.¹, Tshukudu, J.L.¹, Nthinya, S.K.¹, Mahlake, S.K.¹, Mhlongo, G.¹, Mbhele, F.G.T.¹, and Mnisi, C.M.^1,2,*

¹Department of Animal Science, School of Agricultural Science, North-West University, Mafikeng, South Africa
²Food Security and Safety Niche area, Faculty of Natural and Agricultural Science, North-West University, Mafikeng, South Africa

Malaysian J. Anim. Sci. 2022 25(1): 1-12

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The study evaluated the effect of pre-treating green tea powder (GTP) with different concentrations of polyethylene glycol (PEG), a tannin-binding agent, on chemical composition and in vitroruminal fermentation. The PEG (Mr 4400) was applied at 0 (PEG0), 25 (PEG25), 50 (PEG50), 75(PEG75) and 100 (PEG100) g/kg (v/w). The PEG pre-treatment showed linear and quadratic trends for total soluble phenolics [R2 = 0.510; P = 0.029], but not for dry matter, organic matter, soluble condensed tannins and acid detergent lignin of GTP. Crude protein [R2 = 0.510, P < 0.0001] and neutral detergent fibre [R2 = 0.580, P < 0.0001] showed a linear decrease, but acid detergent fibre [R2 = 0.655, P < 0.0001] showed a linear increase with PEG levels. There were significant quadratic trends for fractions b [R2 = 0.475, P = 0.023] and c [R2 = 0.446, P = 0.001] as well as effective degradability [R2 = 0.474, P = 0.023] in response to PEG concentrations. PEG0 had similar (P > 0.05) potential degradability as PEG50, PEG75 and PEG100. The PEG25 treatment had the higher effective gas production (73.1 ml/g OM) than PEG75 and PEG100, which did not differ (P > 0.05). Organic matter degradability (OMD) linearly increased at 24-h [R2 = 0.344; P = 0.003], but declined at 36-h [R2 = 0.190; P = 0.190] post-incubation as PEG levels increased. Significant linear and quadratic trends were observed for 12-h [R2 = 0.389; P = 0.032] and 24-h [R2 = 0.637; P = 0.040] partitioning factors as PEG concentrations increased. It can be concluded that PEG pretreatment of GTP reduced total soluble phenolics, crude protein and neutral detergent fibre, and improved fermentation efficiency. Based on the quadratic responses for the degradation kinetics and partitioning factors, the optimum PEG treatment for maximum ruminal fermentation efficiency of green tea powder was determined to be 50 g/kg.