AFIA - Laboratory Methods Manual - Australian Fodder Industry ...

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j) Cool for at least 30 minutes but not more than 3 hours before weighing. Record the weight (W6) to 0.1mg. Calculation: Laboratory dry matter % (Lab DM %) = { (W6 - W4) / (W5 - W4) } X 100% Where: W4 = Empty weight of container in grams W5 = Initial weight of sample in grams W6 = Dry weight of sample and container in grams Step 3: Calculation of Percent Total Dry Matter Total Dry matter % (%DM) = { (Partial dry matter%) X (Laboratory dry matter%) } /100. References: = { (W3 - W1) / W2} X { (W6 - W4) / (W5 - W4) } X 100% National Forage Testing Association - Forage Analysis Procedures 2.2.1 Partial Drying of Wet Samples. National Forage Testing Association - Forage Analysis Procedures 2.2.2.5 Dry Matter by Oven Drying for 3 hr at 105 o C. FEEDTEST, DPI Vic, Hamilton, Victoria - Method Manual, Method 2.1 Determination of Dry Matter. AFIA Laboratory Methods Manual – v7 September 2011 Page 16 of 103
Appendix 1.3R(1): Method for Silage Samples Scope: Silages contain a volatile dry matter (DM) fraction that is lost with oven drying and freeze drying. This fraction contains volatile fatty acids, alcohols and volatile nitrogen (N) compounds. The loss of volatiles varies with the extent and type of silage fermentation, and is generally higher with low DM silages where there is usually a more extensive fermentation. With higher DM silages (> 50 % DM) there is a more restricted fermentation so the volatile loss on oven drying is less. As the volatile compounds in silage are completely digestible, it is important to take this into account when calculating digestibility, otherwise digestibility will be underestimated. Owing to volatile N losses, the total N content of silages will also be underestimated if analyses are conducted on oven dried samples. All other analyses on silages will be overestimated unless a correction is made for the volatile DM content. Principle: A laboratory reference method that specifically determines water content is needed to allow the calculation of the true DM content of silages and other fermented feeds. The Karl Fischer method has been found to be suitable and is now semi-automated through the use of Karl Fischer titrators. The method has been described by Kaiser et al. (1995) and involves the extraction of silage moisture in methanol, and then determining water content of the extract using a Karl Fischer titrator. The above procedure, while suitable for research laboratories, is less appropriate for commercial feed testing laboratories. In this situation, an alternative approach is to use a correction equation(s) to predict true DM from an oven DM measurement. As the correction required will be influenced by the oven drying regime adopted, it is important that the correction equation selected is applicable to the oven drying temperature used. Procedure: An earlier correction equation provided by Kaiser et al. (1995) calibrated true DM against oven DM determined at 80ºC. This was based on a relatively small number of silages. To increase the number and the range of silages, two correction equations have been developed at the Wagga Wagga Agricultural Institute, for silages oven dried at 80ºC for 24 hours (one-stage method) and at 60ºC for 24 hours (first stage of two-stage method, i.e. Partial DM). (a) Correction for silages dried at 80ºC This correction equation has been based on 102 silage samples from studies at the Wagga Wagga Agricultural Institute (Kaiser et al. 1995; Kaiser and Kerr 2003). The silages covered a wide range of crops and pastures with oven DM contents (80ºC) in the range 18.0-72.8 %. Estimated True DM (%) = 3.846 + (0.96 × oven DM %) (r 2 = 0.99; s.e. = 1.28) (b) Correction for silages dried at 60ºC This equation is based on 60 silage samples (a subset from the above study by Kaiser and Kerr 2003). The silages covered a wide range of crops and pastures and had DM contents (60ºC) in the range 20.6-78.1 %. Estimated True DM (%) = 4.686 + (0.89 × oven DM %) (r 2 = 0.98; s.e. = 1.61) Comments: • The correction in (a) above was developed in a research project at the Wagga Wagga Agricultural Institute, Department of Primary Industries NSW, with support from Dairy Australia, Meat & Livestock Australia, and the Rural Industries Research and Development Corporation. AFIA Laboratory Methods Manual – v7 September 2011 Page 17 of 103
Page 1 and 2: AFIA - Laboratory Methods Manual A
Page 3 and 4: FOREWORD This manual is the result
Page 5 and 6: TABLE OF CONTENTS SECTION 1: AFIA R
Page 7 and 8: SECTION 1 AFIA REFERENCE AND APPROV
Page 9 and 10: Sample Coning and Quartering: This
Page 11 and 12: Version 2 Date 31/08/05 Method - 1.
Page 13 and 14: l) Grind the coarse material in a c
Page 15: Procedure: Step1. Partial dry matte
Page 21 and 22: Procedure: Note: Analyses are usual
Page 23 and 24: Appendix 1.4R(1): Determining the C
Page 25 and 26: 7. Include two blanks and three dri
Page 29 and 30: 4. Store the sample in a refrigerat
Page 31 and 32: Version 4 Date 22/05/2011 Method -
Page 33 and 34: 4. Weigh out unknown samples and in
Page 35 and 36: Correction for silage DMD slope For
Page 37 and 38: Preparing an aNDF Solution: a) Pour
Page 39 and 40: Comments: • Difficult filtration
Page 41 and 42: Appendix 1.8R(1): NFTA Method 5.2:
Page 43 and 44: Comments: • The volume of the amy
Page 47 and 48: 8. Add 2000 mL of ambient temperatu
Page 51 and 52: 10. When the reagent starts to boil
Page 53 and 54: Undersander D, Mertens DR, Thieux N
Page 55 and 56: 14. Determine the number (n) of sam
Page 57 and 58: Procedure: 1. Samples should be mic
Page 59 and 60: Appendix 1.9R(1): Differences in th
Page 61 and 62: Normality MUST be verified by titra
Page 63 and 64: Van Soest PJ, Robertson JB and Lewi
Page 65 and 66: Normality MUST be verified by titra
Page 67 and 68:
Goering HK and van Soest PJ (1970).
Page 69 and 70:
• Slide the desiccator lid open.
Page 71 and 72:
Funnels, plastic Procedure: 1. Weig
Page 73 and 74:
Appendix 1.11R(1): Notes on the Ant
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Version 1 Date 31/08/05 Method - 1.
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Make up all working standards to vo
Page 79 and 80:
Figure 1 Carrier/water Blue/Blue 2.
Page 81 and 82:
Store the electrode in 0.1M KCl sol
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Laboratory samples must be equilibr
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Safety Precautions: • There shoul
Page 87 and 88:
SECTION 2 AFIA REFERENCE PROCEDURES
Page 89 and 90:
Version 2 Date 31/08/05 Method - 2.
Page 91 and 92:
Method - 2.2R: Calculation of Metab
Page 93 and 94:
Appendix 2.2R(1). Calculation of Or
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SECTION 3 DRAFT METHODS Draft metho
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Reagents: 1. Stock Solution A. Ther
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Calculations: Percent Starch on DM
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5. Sodium hydroxide solution, 10M.
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Acceptance of results: The r 2 valu
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