Page 103 - Raw Diet References Book 2019

Faeces Faeces shall be analyzed using composite appropriate assays. Ample quantities of the remaining
samples. The samples shall be blended to ensure a sample should be frozen and retained until assay
uniform consistency and an adequate quantity used for results have been reviewed and found acceptable.

Urine Urine shall be collected in sulphuric acid collection period shall be freeze dried and pooled per
containing receptacles to stabilize the urine and animal in sufficient amount for GE assay.
prevent loss of nitrogen. Aliquots of urine from the

1.2.9 Analytical determination

Prepared samples shall be used for analysis. AOAC Food and faeces are analysed for the indicator by the
approved analytical methodology shall be used when same method (Atomic absorption spectrophotometry
available or one of the recommended analytical is the preferred method if chromic oxide is used as
methods listed on p. 33. Food and faeces shall be the indicator (Arthur 1970). Since controlled sample
assayed for gross energy (bomb calorimetry), crude digestion and oxidation of the chromic oxide
protein, and the indicator. If urine is collected, gross to chromates is critical for reproducible results,
energy and crude protein in the urine should also be colorimetric analysis of chromium is less reproducible
determined. than atomic absorption spectrophotometry.

If digestibility values of dry matter, fat or other Food, faeces and urine (if collected) are stored in
nutrients are wanted, food and faeces should also be the freezer in case of need for further analysis
assayed for those substances.

1.2.10 Calculation of digestible energy and digestible nutrients

Digestible energy & protein The determination is consumed minus the energy or crude protein in the
based on assays of the gross energy or crude protein faeces.

{1 - (GE of faeces x % Cr2O3 in food) } x GE of food
DE (kcal or kJ/g) =
(GE of food x % Cr2O3 in faeces)

{1 - (% CP in faeces x % Cr2O3 in food) } x CP in food
DP (% food) =
(% CP in food x % Cr2O3 in faeces)

Digestible fat, ash and dry matter can be calculated in the same way as digestible protein.

1.2.11 Calculation of metabolizable energy

Metabolizable energy The determination is based energy lost in faeces and in the urine.
on assays of the gross energy consumed minus the

If urine is collected ME (kcal or kJ/g) = DE - GE of urine

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