Digestibility standardised

The data for amino acid digestibility in the pig are taken from AFZ, Ajinomoto Eurolysine, Aventis Animal Nutrition, INRA, ITCF, 2000. AmiPig. Standardised Ileal Digestibilit/ of amino acids in feedstuffs for pigs, AFZ, Paris. (Document available at www.feedbase.com/amipig)... 

Furuya and Kaji (1991) have shown that, contrary to the values of apparently digestible AA (not corrected), the values of truly digestible AA are additive. This is explained by the fact that, as is the case for the quantities of truly undigestible AA, they are strictly proportional to the protein content of the feed material being studied. To avoid confusion with the concept of real digestibility, it is now preferable to use the term standardised digestibility . 

The standardised ileal digestibility values (SID) depend on the estimation of basal endogenous losses of N or of each AA. If the animals do not receive the diet for a long period, the use of a protein-free diet is the most appropriate method to measure these losses. It has been shown that the basal endogenous losses, when measured using protein-free diets of similar composition (Seve et o/., 2000), depend on the laboratory where they were measured. 

This corresponds to the following relationship between the corrected apparently digestible AA content (Corrected AlDC) and the standardised digestible AA content (SIDC).both expressed per kg dry matter of the feed material ... 

Standardised digestibility system or apparent digestibility system ... 

Over the last few years, the measurement methodology of the nutritional value of feedstuffs has been the topic of concerted studies at the European level, with particular emphasis on the standardisation of in vivo methods (Perez et o/., 1995a) and on the harmonisation of analytical methods for feeds and faeces (EGRAN, 2001). This resulted in the adoption of a European reference method to determine the digestibility of diets (Perez et al., 1995b) and in the harmonisation of the procedures used to calculate the nutritional value of feed materials within mixtures of feedstuffs (Villamide et al., 2001). 

Standardised ileal digestibility of an amino acid for pigs, in %... 

Digestible amino acid content corresponding to the standardised ileal digestibility for pigs, in g/kg... 

It is assumed that industrial amino acids obtained by chemical synthesis or fermentation are totally digestible in monogastric species. This corresponds to a value of 100% for standardised digestibility (SID) In the pig and true digestibility (TD) in poultry. However, this is not the case for the methionine hydroxy-analogue (see note 3). 

As a result, specified periods of time, specific disposal pathways, and standard test methodologies were incorporated into definitions. Standardisation organisations such as CEN, ISO, and ASTM were consequently encouraged to rapidly develop standard biodegradation tests so these could be determined. Society further demanded undebatable criteria for the evaluation of the suitability of polymeric materials for disposal in specific waste streams such as composting or anaerobic digestion. Biodegradability is usually just one of the essential criteria, besides ecotoxicity, effects on waste treatment processes, etc. 

Human Engineering Design Data Digest, Human Factors Standardisation, Department of Defense, Human Factors Engineering Technical Advisory Group. 

The concept of standardised ileal digestible amino acids makes no allowance for an excess of an individual amino acid, which, in certain circumstances, could be substantial. It is usual therefore to limit the concentration of any one amino acid to less than 1.2 times that of the value presented in Table 13.7. It is also assumed in calculating the requirement for standardised ileal digestible amino acids that the proportions of amino acids made available to the metabolic body pool are the same as those in the dietary protein. This will not be so if the acids are not digested or absorbed to the same extent. 

Standardised digestibility takes account of only part of the endogenous nitrogen and remains an apparent figure. 

For poultry, evaluation of protein sources is also based on standardised ileal digestibility of the three major amino acids lysine, methionine and tryptophan. 

In addition to a general requirement for protein, non-ruminant animals have a specific dietary requirement for the ten or so essential (or indispensable) amino acids. Over the past 30 years many experiments have been conducted to determine the quantitative requirements for essential amino acids, and protein requirements have now been supplemented (or even replaced) by requirements for some or all of these amino acids. Requirements may also be stated in terms of ideal protein (protein containing essential amino acids in exactly the proportions required by the animal) or standardised deal digestible amino acids , as explained in Chapter 13. 

Essential amino acid ideal balance of essential amino acids relative to lysine Standardised ileal digestible amino acid requirement (g/day) Dietary amino acid requirement (g/day) ... 

Calculated on the assumption that the standardised ileal digestibility of amino acids is 0.84. If true values are known and different, then values should be calculated accordingly. 

Standardised ileal digestible lysine g/kg diet = 54.7/7.5 = 7.3 g/kg diet... 

Dietary protein is the sole source of essential amino acids for the sow. Diets are usually formulated to standardised ileal digestible lysine, with the proportions of the other acids to lysine being kept the same as those in the ideal protein. 

Food DM (g/kg) NE growing pigs and lactating sows (MJ/kg) NE pregnant sows (MJ/kg) Digestible phosphorus (g/kg) Standardised ileal digestible amino Lysine Methionine + Threonine cysteine acid (g/kg) Tryptophan... 

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