Authors: NİHAT DENEK, SUPHİ DENİZ
Abstract: This study was carried out to determine the dry matter (DM) and organic matter (OM) digestibilities, and metabolizable energy levels of some forages commonly used in ruminant nutrition by 2 different in vitro methods; the enzyme technique and the 2- stage method (rumen fluid + HCl-pepcine). Seven different samples of alfalfa hays, sainfoin hay and grass hay, and 4 different samples of wheat straws, lentil straw, corn silage and sorghum silage were used in the experiment. DM digestibilities were 51.53% for alfalfa hay, 47.79% for sainfoin hay, 41.02% for grass hay, 30.15% for wheat straw, 47.81% for lentil straw, 63.74% for corn silage and 53.25% for sorghum silage by the enzyme technique (P < 0.05). OM digestibilities and metabolizable energy levels were 57.93% and 9.11 MJ/kg DM for alfalfa hays, 52.68% and 8.28 MJ/kg DM for sainfoin hay, 46.37% and 7.31 MJ/kg DM for grass hay, 33.73% and 5.25 MJ/kg DM for wheat straw, 53.49% and 8.19 MJ/kg DM for lentil straw, 67.92% and 10.74 MJ/kg DM for corn silage, and 56.75% and 8.88 MJ/kg DM for sorghum silage by enzyme technique (P < 0.05). DM and OM digestibilities and metabolizable energy levels were 56.32%, 61.36% and 9.28 MJ/kg DM, respectively, for alfalfa hays, 50.21%, 56.21% and 9.07 MJ/kg DM, respectively, for sainfoin hay, 45.31%, 51.41% and 7.75 MJ/kg DM, respectively, for grass hay, 41.34%, 47.08% and 7.55 MJ/kg DM, respectively, for wheat straw, 49.67%, 56.56% and 9.16 MJ/kg DM, respectively, for lentil straw, 63.19%, 70.02% and 10.57 MJ/kg DM, respectively, for corn silage and 53.75%, 57.16% and 9.01 MJ/kg DM, respectively, for sorghum silage by the 2- stage method (P < 0.05). When the 2 techniques were compared, the estimations of DM and OM digestibilities and metabolizable energy levels by both techniques were similar (P > 0.05) in all forages, except for wheat straw. DM and OM digestibilities and metabolizable energy levels of wheat straw were lower with the enzyme technique compared to the 2- stage method (P < 0.05). In conclusion, the 2- stage method can be an alternative technique for determining forage digestibility and metabolic energy content to classical digestion trials.
Keywords: Forage, in vitro digestibility, metabolizable energy level
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