In vitro rumen degradability of crude protein in seeds from four Sesbania spp. and the effects of treatments designed to reduce the levels of antinutrients in the seeds

Abstract

Seeds of four species of Sesbania ( Sesbania aculeata, Sesbania rostrata, Sesbania sesban (accession 10865D) and S. sesban (accession 15019D) were chemically analysed for CP, lipid, ash, NDF, ADF and ADL, and in vitro organic matter digestibility (OMD) percent, in vitro rumen degradable protein (RDP) percent, in vitro production and composition of short chain fatty acids (SCFA) were determined. Effects of different treatments (soaking in water for 24 h, soaking+autoclaving at 121 °C for 30 min, autoclaving and dry heating 130 °C for 1 h) on N solubility and various antinutrient levels such as total phenols, tannins, condensed tannins, phytic acid, saponin and trypsin inhibitor activity (TIA) in different seeds were also determined. The OMD% and RDP% in different seeds ranged from 67 to 72.3% and 42.7 to 73.7%, respectively and total SCFA values from 209.7 to 239.1 μmol/g DM incubated. The N solubility of raw seeds in 0.036 M, KOH ranged from 81 to 89% and was reduced by all heat treatments (i.e. from 44 to 56%, 46 to 56% and 42 to 55% in soaked+autoclaved, autoclaved and dry heated seeds, respectively). The four treatments reduced antinutrients by the following amounts: total phenols 38–56, 48–58, 42–50 and 23–30%; tannins 34–49, 39–56, 40–44 and 24–36%; condensed tannins 8–17, 40–45, 33–41, 17–25%; phytic acid 16–32, 33–46, 32–38, 31–36%; saponin 14–15, 30–43, 17–27 and 16–25%; TIA 3–13, 81–93, 80–93 and 83–94% by soaking, soaking+autoclaving, autoclaving and dry heating treatments, respectively. Haemagglutination activity was unaffected by soaking but almost totally destroyed by the three thermal treatments. In general, soaking+autoclaving was the most effective treatment for reducing the antinutrient levels in different Sesbania seeds.