Agriculture Reference
In-Depth Information
IAAR s from summarized literature data.
In  general, more studies are required to
evaluate and to validate different assump-
tions about IAAR s in chicken and pig diets.
These applications within the non-linear
modelling procedure are currently at the
starting point and need to be further devel-
oped and validated in future investigations.
Through this research it will be possible to
link evaluations of sustainability in food pro-
ducing animals more successfully with the
physiological processes of nutrient conver-
sion in these animals.
In this chapter the basics and current de-
velopments of an exponential modelling pro-
cedure were described, and experimental
results in growing animals were presented in
an effort to contribute to an improved under-
standing of the 'Goettingen approach'. The
objective was not to provide a general over-
view of the model applications in this field
that are based on different hypotheses. Con-
sequently, only a very limited number of ref-
erences were cited.
In summary, the 'Goettingen approach'
has the potential to model the process of
converting feed into food protein by taking
into account optimized dietary AA supply
at a desired level of performance within the
estimated threshold value of genetic poten-
tial for growth, and the AA efficiency in the
feed. However, an important factor that may
impact both the derived AA requirements
and the resultant IAAR is is the extent to
which AA efficiency varies in feed, as this
has not been systematically investigated.
This unknown variation may also have an
impact on the derived recommendations for
improving sustainability parameters of the
conversion process with growing animals.
These main factors of influence need more
attention in future investigations and will
extend the field for validated applications
of the 'Goettingen approach' for modelling
of nutrient conversion processes in food
producing animals.
Applications in evaluation of sustainability
of feed to food protein
From the viewpoint of the currently increas-
ing interest in evaluating the sustainability of
food-producing systems with agricultural ani-
mals, minimized N pollution per unit N de-
position is of substantial interest as a means of
improving sustainability of nutrient conver-
sion processes with food producing animals.
In this context it would be useful to
know what proportion of the genetic poten-
tial ( ND max T ) of growing animals would be
optimal for maximizing metabolic efficiency.
According to the shape of the exponential
function (Fig. 6.2 ) it cannot be expected that
a very high percentage of the threshold value
could be achieved with high metabolic effi-
ciency. Our model applications dealing with
this important question indicated initially
that an average level of performance could
be more advantageous for minimizing NEX
per unit ND (Liebert and Wecke, 2010). How-
ever, decisions in this field are more com-
plex because both the level of daily protein
supply and the yielded dietary AA balance
( IAAR ) in terms of AA efficiency have to be
taken into account. Variation in dietary AA
efficiency of feed ingredients is an important
factor of influence. By improving the agree-
ment between the IAAR s needed and the AA
balance in the diet, the acceptable level of
growth performance will be elevated if in the
future any reference value or upper limit for
the ratio NEX : ND is fixed for individual
food-producing species.
References
Baker, D.H. (2003) Ideal amino acid patterns for broiler chicks. In: D'Mello, J.P.F. (ed.) Amino Acids in
Animal Nutrition . CAB international, Wallingford, UK, pp. 223-235.
Block, R.J. and Mitchell, H.H. (1946) The correlation of amino acid composition of proteins with their
nutritive value. Nutrition Abstracts and Reviews. 16, 249-278.
Emmert, J.L. and Baker, D.H. (1997) Use of the ideal protein concept for precision formulation of
amino acid levels in broiler diets. Journal of Applied Poultry Research 6, 462-470.
 
Search WWH ::




Custom Search