Inter-laboratory variation of in vitro cumulative gas production profiles of feeds using manual and automated methods

Rymer, C., Williams, B. A., Brooks, A. E., Davies, D. R. and Givens, D. I. (2005) Inter-laboratory variation of in vitro cumulative gas production profiles of feeds using manual and automated methods. Animal Feed Science and Technology, 123-124 part1: 225-241. doi:10.1016/j.anifeedsci.2005.04.029


Author Rymer, C.
Williams, B. A.
Brooks, A. E.
Davies, D. R.
Givens, D. I.
Title Inter-laboratory variation of in vitro cumulative gas production profiles of feeds using manual and automated methods
Journal name Animal Feed Science and Technology   Check publisher's open access policy
ISSN 0377-8401
Publication date 2005-09-30
Sub-type Article (original research)
DOI 10.1016/j.anifeedsci.2005.04.029
Volume 123-124
Issue part1
Start page 225
End page 241
Total pages 17
Place of publication The Netherlands
Publisher Elsevier B.V.
Language eng
Subject 070204 Animal Nutrition
Abstract A study was conducted to estimate variation among laboratories and between manual and automated techniques of measuring pressure on the resulting gas production profiles (GPP). Eight feeds (molassed sugarbeet feed, grass silage, maize silage, soyabean hulls, maize gluten feed, whole crop wheat silage, wheat, glucose) were milled to pass a 1 mm screen and sent to three laboratories (ADAS Nutritional Sciences Research Unit, UK; Institute of Grassland and Environmental Research (IGER), UK; Wageningen University, The Netherlands). Each laboratory measured GPP over 144 h using standardised procedures with manual pressure transducers (MPT) and automated pressure systems (APS). The APS at ADAS used a pressure transducer and bottles in a shaking water bath, while the APS at Wageningen and IGER used a pressure sensor and bottles held in a stationary rack. Apparent dry matter degradability (ADDM) was estimated at the end of the incubation. GPP were fitted to a modified Michaelis–Menten model assuming a single phase of gas production, and GPP were described in terms of the asymptotic volume of gas produced (A), the time to half A (B), the time of maximum gas production rate (tRM gas) and maximum gas production rate (RM gas). There were effects (P<0.001) of substrate on all parameters. However, MPT produced more (P<0.001) gas, but with longer (P<0.001) B and tRM gas (P<0.05) and lower (P<0.001) RM gas compared to APS. There was no difference between apparatus in ADDM estimates. Interactions occurred between substrate and apparatus, substrate and laboratory, and laboratory and apparatus. However, when mean values for MPT were regressed from the individual laboratories, relationships were good (i.e., adjusted R2 = 0.827 or higher). Good relationships were also observed with APS, although they were weaker than for MPT (i.e., adjusted R2 = 0.723 or higher). The relationships between mean MPT and mean APS data were also good (i.e., adjusted R2 = 0.844 or higher). Data suggest that, although laboratory and method of measuring pressure are sources of variation in GPP estimation, it should be possible using appropriate mathematical models to standardise data among laboratories so that data from one laboratory could be extrapolated to others. This would allow development of a database of GPP data from many diverse feeds.
Keyword Gas production
Ring test
Feed characterisation
Manual pressure transducer
Automated pressure system
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
Centre for Nutrition and Food Sciences Publications
 
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Created: Tue, 31 Mar 2009, 15:53:31 EST by Ms Sarada Rao on behalf of Centre for Nutrition and Food Sciences