Estimation of organic matter digestibility, metabolizable energy, phenolic compounds and antioxidant activity of stems and seeds of the Juncus acutus plant in ruminant nutrition

Abstract

The objectives of the present study were to determine the organic matter digestibility (OMD), metabolizable energy (ME), antioxidant activity and total phenolic and flavonoid concentrations of stems and seeds of Juncus acutus. Stem and seed samples were collected from Hamsiloz Bay in Sinop, Turkey, and the proximate analysis was carried on them. The OMD percentage and ME values of the samples were estimated from gas measured by the in vitro gas production method. Phenolic and flavonoid concentrations and total antioxidant activity were determined spectrophotometrically. Mean OMD, ME_OMD and ME_GP levels and gas production kinetic parameters A, c and T_1/2 of J. acutus stem and seed samples were 40.3% and 47.7%; 6.44 and 7.63 MJ/kg DM, 5.96 and 7.07 MJ/kg DM, 35.12 and 47.19 mL, 0.055% and 0.092%, and 12.60 and 7.53 h, respectively. Mean OMD percentage, ME and gas production kinetic parameters A, c and T_1/2 of the stems were significantly different than that of the seed. The antioxidant activity, total phenolic and flavonoid concentrations of stems and seeds of J. acutus were 88.45 and 88.48 IC50 mg/mL, 19.70 and 40.99 mg GAE/100 g and 0.63 and 1.20 mg Qe/100 g, respectively. Mean values of total phenolic and flavonoid concentrations of stems were significantly different from that of the seeds. In conclusion, both stems and seeds of J. acutus may be considered alternative feed sources for ruminants. Furthermore, when J. acutus stems and seeds are included in ruminant diet, the phenolic compounds may contribute to the intake of natural antioxidants.

Keywords: In vitro gas production, Juncaceae, flavonoid compounds, spiny rush, sharp rush