Author
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Mertens, David |
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Submitted to: British Society of Animal Science Occasional Publication Series
Publication Type: Proceedings Publication Acceptance Date: 8/18/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Measuring in vitro gas production early in fermentation as a selection criteria for plant breeding provides unique challenges because thousands of materials must be evaluated, duplication of analyses is limited, and the range in gas production at 3 h or less is relatively small compared with variation due to inoculum differences. The objectives of this research were to evaluate the use of a reference forage to adjust measurements for run-to-run differences and to identify sources of variation among runs in 3-h gas production of a reference standard. The average gas produced by the lucerne reference after 3 h of fermentation was 6.60 mL of CO2 per 0. 11 g of air-dry matter with a standard error among days of 0.34. Although adjusting data for the lucerne reference standard did not eliminate differences among days, it reduced the daily range in 3-h gas production significantly. The reference standard also was a significant variable in all statistical models used to evaluate genotype differences which suggests that it is useful in removing uncontrolled variation. Daily deviations in gas production of the lucerne reference standard were related to OD, but not pH, of the composite inoculum. Temperature regulation is a crucial factor in measuring gas production during fermentation and ruminal microorganisms seem to have a narrow temperature optimum. Although inoculum preparation procedures can minimize daily variation in in vitro gas production, a composite inoculum, of strained ruminal fluid and strained blended solids from two cows resulted in significant daily deviations. Suitable reference standards and perhaps the OD of the inoculum may be useful in adjusting for run-to-run variation when measuring gas production during short fermentation times. |
