Abstract
The objective of this study was to evaluate the effects of halogenated compounds, organic acids, unsaturated fatty acids and their mixtures on in vitro methane production and fermentative characteristics of mixed rumen microorganisms. Agents used in two in vitro experiments were bromoethanesulfonic acid (BES) and pyromellitic diimide (PMDI) as halogenated compound, fumarate and malate as organic acid, and linoleic acid and linolenic acid as unsaturated fatty acid sources. Ruminal fluid collected from a Holstein steer fed tall fescue and concentrate mixtures was incubated at 39°C for 48 h with addition of those materials. Single supplementation of halogenated compounds, organic acids or unsaturated fatty acids decreased in vitro methane production (p<0.05). The second experiment was designed to investigate effects of combination of one of halogenated compounds and either organic acids or fatty acids on methane production. Lower concentration of methane and lower A:P ratio were observed with PMDI compared with BES (p<0.01). In general medium pH, VFA, total gas and hydrogen production, and dry matter degradability were affected by addition of the same compounds. In addition, PMDI+malate treatment resulted in the highest molar proportion of propionate, and lowest A:P ratio and methane production (p<0.01). Hydrogen production was highest in PMDI+linolenic acid and lowest in BES+malate treatment (p<0.01). PMDI+malate combination was the most recommendable in reducing methane production without too much influence on digestibility under conditions of present studies. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 9 : 1255-1259)
Highlights
Methane production during anaerobic fermentation in the rumen is a nutritionally wasteful process which represents 2 to 15% gross energy loss to the host animal (Moss, 1993)
Several methods have been proposed as a means of reducing methane production in the rumen, and some of examples are: proportion of concentrates in the diet (Lee et al, 2003), processing of forages (Takahashi, 2001; Santoso et al, 2003), heat treatment of concentrates (Thomson, 1972), and some methane inhibitors such as halogenated compounds (Martin and Macy, 1985), ionophores
While single supplementation of organic acids had little effect on methane production, mixed supplementation of organic acids and monensin decreased methane production (Callaway and Martin, 1996). It is not apparent why combinations of two compounds resulted in the reduction of methane production, but it may be possible that one compound such as monensin reduce the number of methanogens and the other compound serves as an alternative electron sink
Summary
ABSTRACT : The objective of this study was to evaluate the effects of halogenated compounds, organic acids, unsaturated fatty acids and their mixtures on in vitro methane production and fermentative characteristics of mixed rumen microorganisms. Agents used in two in vitro experiments were bromoethanesulfonic acid (BES) and pyromellitic diimide (PMDI) as halogenated compound, fumarate and malate as organic acid, and linoleic acid and linolenic acid as unsaturated fatty acid sources. Single supplementation of halogenated compounds, organic acids or unsaturated fatty acids decreased in vitro methane production (p
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