IN VITRO RUMINAL AND POST-RUMINAL PROTEIN DEGRADATION OF UNTREATED AND TREATED SOYBEAN MEAL

Document Type : Original Article

Authors

Department of Animal and Fish and Production, Faculty of Agriculture, University of Alexandria, Egypt.

Abstract

This study was designed to determine the characteristics of rumen fermentation, and post-ruminal protein digestion of untreated and treated soybean meal (SBM) using gas production (GP) technique and three step in situ/in vitro procedures. Soybean meal (SBM) was treated by autoclaving, roasting, with ethanol and mixed by various proportions of  Acacia saligna (AS) leaves (1:3, 1:1, 3:1) ratios. The results showed that the highest cumulative GP was observed in untreated SBM followed by treated SBM with ethanol, roasted SBM and SBM+AS (3:1). The lowest mean values of GP were obtained in SBM+AS (1:3), autoclaved SBM and SBM+AS (1:1). The predicted metabolizable energy (ME, MJ/kg DM) and net energy (NE, MJ/kg DM) varied widely in substrates and was particularly high in untreated SBM, while SBM+AS (1:3) had significantly the lowest values of ME and NE. The highest mean values of NH3-N concentration were obtained with untreated SBM, while the lowest was obtained with autoclaved SBMand followed by SBM+AS (1:3), ethanol-treated SBM and roasted SBM. Rumen degradable protein (RDP, %) varied from 33.6% in autoclaving SBM to 62.4% in SBM+AS (3:1). Intestinal protein digestion (IPD, %) content was highest in autoclaving-SBM, roasting SBM and untreated SBM and lowest mean value of IPD was recorded in SBM+AS (1:1).The highest mean values for VFA concentrations were obtained with SBM+AS (3:1)and SBM treated with ethanol followed by SBM plus A. saligna leaves (1:3). The lowest mean value of VFA concentration was obtained by autoclaving SBM or roasting SBM. It is concluded that autoclaving SBM, ethanol- treated SBM and mixing SBM with Acacia leaves (1:3) could be used advantageously to reduce RDP and increase the bypass protein but the autoclaving SBM showed the best treatment on improving the intestinal protein digestion of SBM.

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