Assessment of in vitro ruminal fermentation characteristics, methane (CH4) production, and associative effects between low-quality roughages and protein supplements
Muhammad Khairul Bashar1, Eva Haese2, Markus Rodehutscord3
1University of Hohenheim, Dept. of Animal Nutrition, Germany
To evaluate the in vitro fermentation, CH4 reduction, and associative effects between low-quality roughages and protein feeds, rice straw (RS), German grass (GG), Napier silage (NS), and maize silage (MS) were incubated alone or after replacement by Ipil-ipil or Gliricidia at levels of 10%, 20%, 30%, and 40%, respectively, using the Hohenheim Gas Test. An amount of 200 mg was incubated with rumen fluid-buffer solution for 72 h to measure gas production (GP) and calculate organic matter digestibility (dOM) and metabolisable energy (ME). Additionally, 120 mg of feed were incubated for 24 h to determine the CH4 concentration in the GP. Associative effects between feed ingredients were calculated by comparing the measured and estimated values of the composite feed and the estimated values were the weighted mean of the values of fermentation of the individual feeds. The GP24 and rumen fermentation rate increased (p<0.05) as the level of Ipil-ipil added to RS was increased. Increasing the Ipil-ipil level resulted in a gradual increase in dOM and ME (p<0.05) of the mix, reaching maximum values (59.1% and 7.60 MJ ME/kg DM, respectively) and maximum reductions in CH4 concentration and CH4/dOM (6.89% and 11.7%, respectively) compared to the control, when Ipil-ipil was added at 40% DM. When Ipil-ipil was added at 30% to NS, the same trend was observed for dOM and ME (56.5%, and 7.55 MJ ME/kg DM, respectively) and CH4 concentration and CH4/dOM (5.32% and 13.3%, respectively). No significant interaction was observed between Ipil-ipil and good quality roughages like GG and MS. The opposite trend was found for GP24, dOM, ME, and CH4 production when an increasing level of Gliricidia was added to the roughages. A positive associative effect was obtained for all mixed treatments (p<0.05) and showed a maximum when 40% Ipil-ipil was added to RS and 30% Ipil-ipil to NS. In conclusion, based on in vitro rumen fermentation, CH4 production, and associative effects, adding Ipil-ipil to low-quality roughages is superior to Gliricidia and demonstrated promising results and ranked as follows: RS + 40% > NS + 30% Ip > MS + 30% Ip > GG + 10% Ip.
Keywords: Associative effect, CH4 emission, Grass, In vitro fermentation, Leguminous fodder, Rumen digestion
Contact Address: Muhammad Khairul Bashar, University of Hohenheim, Dept. of Animal Nutrition, Wolff-Str. 10, 70599 Stuttgart, Germany, e-mail: kbashar20yahoo.com