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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #121335
Title: A MECHANISTIC APPROACH TO THE ESTIMATION OF INTAKE OF RUMINANTS BY METHANE EXCRETION AND IN VITRO FERMENTATION CHARACTERISTICS

Author
item Blummel, Michael
item Grings, Elaine
item MOSS, A - ADAS NUT SC RES UNIT, UK
item GIVENS, D - ADAS NUT SC RES UNIT, UK

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2001
Publication Date: 6/1/2001
Citation: BLUMMEL, M.R., GRINGS, E.E., MOSS, A.R., GIVENS, D.I. A MECHANISTIC APPROACH TO THE ESTIMATION OF INTAKE OF RUMINANTS BY METHANE EXCRETION AND IN VITRO FERMENTATION CHARACTERISTICS. JOURNAL OF ANIMAL SCIENCE SUPPLEMENT. 2001. v. 79(Suppl. 1). p. 137.

Interpretive Summary: The accuracy of calculating organic matter intake by methane (CH4) production in vivo together with in vitro fermentation characteristics was examined for 15 roughages offered to sheep ad libitum. Methane production was measured by open circuit calorimetry and organic matter intake (OMI) and in vivo digestibility measurements were obtained in metabolic cages. In vitro roughage fermentation characteristics examined were total and proportional short chain fatty acid (SCFA) production, the efficiency of microbial biomass production (EMP), true substrate degradability, and gas production. These variables were used together with stoichiometrical principles of rumen fermentation to compare measured and calculated OMI. Measured OMI and methane production were related (R**2 = 0.86, P < 0.0001) but CH4 production per kilogram organic matter digested in vivo varied significantly (P < 0.05) between roughages. By using CH4 production, in vitro digestibility measurements and various constant values for SCFA proportions (0.7: 0.2: 0.1; 0.6: 0.3: 0.1; 0.5: 0.4: 0.1) for the acetate: propionate: butyrate ratio and for the efficiency (0.2 and 0.4) of microbial production a maximum R**2 of 0.58 was obtained for the relationship between measured and calculated OMI. By measuring the actual in vitro SCFA proportions and EMP, this R**2 could be improved to 0.79 depending which in vitro technique was employed for the estimations of EMP.

Technical Abstract: The accuracy of calculating organic matter intake by methane (CH4) production in vivo together with in vitro fermentation characteristics was examined for 15 roughages offered to sheep ad libitum. Methane production was measured by open circuit calorimetry and organic matter intake (OMI) and in vivo digestibility measurements were obtained in metabolic cages. In vitro roughage fermentation characteristics examined were total and proportional short chain fatty acid (SCFA) production, the efficiency of microbial biomass production (EMP), true substrate degradability, and gas production. These variables were used together with stoichiometrical principles of rumen fermentation to compare measured and calculated OMI. Measured OMI and methane production were related (R**2 = 0.86, P < 0.0001) but CH4 production per kilogram organic matter digested in vivo varied significantly (P < 0.05) between roughages. By using CH4 production, in vitro digestibility measurements and various constant values for SCFA proportions (0.7: 0.2: 0.1; 0.6: 0.3: 0.1; 0.5: 0.4: 0.1) for the acetate: propionate: butyrate ratio and for the efficiency (0.2 and 0.4) of microbial production a maximum R**2 of 0.58 was obtained for the relationship between measured and calculated OMI. By measuring the actual in vitro SCFA proportions and EMP, this R**2 could be improved to 0.79 depending which in vitro technique was employed for the estimations of EMP.