A ring test of a wireless in vitro gas production system

The in vitro gas production (GP) technique has been widely used for feed evaluation. However, variability in results limits useful comparisons. Results from a ring test undertaken in four laboratories (Italy – IT, Spain – SP, Wales – WA and Denmark – DK) using the same wireless equipment (ANKOM Technology), same substrates and same laboratory protocol are presented, including calculation of repeatability and reproducibility according to ISO 5725-2. Hay, maize starch and straw samples and units without sample (blanks) were incubated in five repetitions using rumen inoculum from cows (DK, IT and WA) or sheep (SP). Curves, corrected for blanks, were fitted using an exponential regression model with a lag time. The following variables were considered: (i) GP24 and GP48: raw values at 24 and 48 h (mL/g DM), corrected for blanks; (ii) A: asymptotic GP (mL/g DM); (iii) T1/2: time when half A is produced (h); (iv) GPMR: maximum predicted GP rate (mL/h); (v) L: lag time (h). A mixed model including laboratories as random effect was used. A significant interaction between substrate and laboratories was found for all variables except A. The most repeatable and reproducible results were observed for A and GP48. The results from this ring test suggest the need for more standardisation, particularly in the procedures that occur outside the laboratory.

[1]  M. Theodorou,et al.  A semi-automated in vitro gas production technique for ruminant feedstuff evaluation , 1999 .

[2]  N. Nielsen,et al.  Methods for Measuring and Estimating Methane Emission from Ruminants , 2012, Animals : an open access journal from MDPI.

[3]  N. Rooney,et al.  British Society of Animal Science , 2003 .

[4]  S. Schiavon,et al.  True dry matter digestibility of feeds evaluated in situ with different bags and in vitro using rumen fluid collected from intact donor cows , 2012 .

[5]  J. Cone,et al.  Influence of rumen fluid and substrate concentration on fermentation kinetics measured with a fully automated time related gas production apparatus , 1996 .

[6]  J. Cone,et al.  Ranking of in vitro fermentability of 20 feedstuffs with an automated gas production technique: Results of a ring test , 2005 .

[7]  D. Mertens.  Gravimetric determination of amylase-treated neutral detergent fiber in feeds with refluxing in beakers or crucibles: collaborative study. , 2002, Journal of AOAC International.

[8]  S. Schiavon,et al.  Metabolizable energy content of feeds based on 24 or 48 h in situ NDF digestibility and on in vitro 24 h gas production methods , 2011 .

[9]  A. Pell,et al.  Computerized monitoring of gas production to measure forage digestion in vitro. , 1993, Journal of dairy science.

[10]  R Core Team,et al.  R: A language and environment for statistical computing. , 2014 .

[11]  R. M. Maurício,et al.  In vitro microbial inoculum: A review of its function and properties , 2005 .

[12]  T. Hothorn,et al.  Simultaneous Inference in General Parametric Models , 2008, Biometrical journal. Biometrische Zeitschrift.

[13]  M. C. Mathews,et al.  Influence of storage time and temperature on in vitro digestion of neutral detergent fibre at 48 h, and comparison to 48 h in sacco neutral detergent fibre digestion , 1999 .

[14]  D. Sauvant,et al.  Comparison of the in vitro gas production technique and the nylon bag degradability technique to measure short- and long-term processes of degradation of maize silage in dairy cows , 1999 .

[15]  L. Raab,et al.  The estimation of the digestibility and metabolizable energy content of ruminant feedingstuffs from the gas production when they are incubated with rumen liquor in vitro , 1979, The Journal of Agricultural Science.

[16]  S. Schiavon,et al.  In vitro rumen fermentation: Effect of headspace pressure on the gas production kinetics of corn meal and meadow hay , 2010 .

[17]  M. Theodorou,et al.  A simple gas production method using a pressure transducer to determine the fermentation kinetics of ruminant feeds. , 1994 .

[18]  R. Bacilieri,et al.  Simplified milk-recording protocols adapted to low-input environments with very small herd size. , 2008, Animal : an international journal of animal bioscience.

[19]  M. Herrero,et al.  The influence of diet of the donor animal on the initial bacterial concentration of ruminal fluid and in vitro gas production degradability parameters. , 2000 .

[20]  Jens C. Streibig,et al.  Bioassay analysis using R , 2005 .

[21]  G. Broderick,et al.  Post-prandial compositional changes of fluid- and particle-associated ruminal microorganisms. , 1987, Journal of animal science.

[22]  F. Masoero,et al.  Technical note: precision and accuracy of in vitro digestion of neutral detergent fiber and predicted net energy of lactation content of fibrous feeds. , 2010, Journal of dairy science.

[23]  A. Borba,et al.  Study of gas production capacity by three sources of inocula , 1996, The Journal of Agricultural Science.

[24]  H. H. Laar,et al.  Repeatability and reproducibility of an automated gas production technique , 2006 .

[25]  P. H. Robinson,et al.  Laboratory variation of 24 h in vitro gas production and estimated metabolizable energy values of ruminant feeds , 2002 .

[26]  Kh Menke,et al.  Estimation of the energetic feed value obtained from chemical analysis and in vitro gas production using rumen fluid , 1988 .

[27]  D. Givens,et al.  In vitro cumulative gas production techniques: History, methodological considerations and challenges , 2005 .

[28]  W. Burroughs,et al.  Suction Strainer Technique in Obtaining Rumen Fluid Samples from Intact Lambs , 1962 .

[29]  D. Mertens,et al.  In vitro fermentation vessel type and method alter fiber digestibility estimates. , 2008, Journal of dairy science.

[30]  H. Bachmann,et al.  Influence of inoculum source on gas production profiles , 2002 .

[31]  K. Südekum,et al.  Comparison of gas accumulation profiles of several feeds using manual or automated gas production methods , 2008 .

[32]  Michael Blümmel,et al.  In vitro gas measuring techniques for assessment of nutritional quality of feeds: a review , 1998 .