ECONOMICS OF USING AMINO ACIDS

5.1 Feed specification
A nutritionist must define a certain nutrient level of the feed he wants
to produce. By reviewing recommendations from different sources, research
reports in the scientific literature, and the perspectives gained
by personal experience they can establish reasonable nutrient levels
for feeds. These nutrient levels can be strongly influenced by production
goals. These goals may be varied, from weight of production (live
weight gain, egg mass, milk quality) to the efficiency of production or
even per specific unit of output (breast meat yield, lean meat or milk
constituent). Thus approaches must be chosen that allow nutritionists
to optimally determine the correct level of amino acids in feed.
Calculating optimal dietary amino acid levels are based on economic
key figures and can be modelled. This model not only considers
changing feed cost with changing amino acids level, but also considers
the effects of changing dietary amino acids on breast meat yield
which in turn affects the income. Changing economic conditions will
thus have an impact on the optimal dietary amino acid of a feed.
The two most prominent definitions for profitability are “feed cost/kg
weight gain or breast meat” and “gross margin” which means the income
over feed cost per pig or per flock of birds.
Meta-analyses of performance data of broilers and pigs show that the
chosen parameter has a strong impact on the determination of the nutrient
level i.e. minimizing Feed cost/kg weight gain, or maximising weight
gain and breast meat yield, or even minimising feed conversion ratio.
An example based on broiler experiments is given in Figure 9. Broilers
were fed increasing levels of L-Threonine which were added to a
threonine deficient basal diet from day 21 to 42. Dose-response data
on weight gain and feed conversion ratio were analysed by exponential
regression. Regression curves are showing feed cost/kg gain (i.e.
combination of feed conversion ratio with feed cost), or gross margin
(i.e. combination of weight gain and feed conversion ratio with price/
kg gain and feed cost). Optimal dietary amino acid levels were higher
for maximising gross margin compared to minimising feed cost/kg
gain. Accordingly, gross margin maximised at 0.83 % dietary digestible
threonine whereas feed cost/kg gain minimised at 0.75 %, respectively.
Nowadays, recommended amino acid levels allow for maximum technical
or biological performance which is not necessarily the same as
best economic performance. However, various ways of expressing
profitability are available and comparison of feed cost/kg gain and
gross margin suggest that gross margin should be preferred because
it not only considers amino acid effects on feed conversion ratio but
also those on growth. Moreover, it has been demonstrated that the
goal of animal protein production drives the optimal dietary amino
acid levels and consequently the lowest cost of feed typically does
not provide the best economic returns.
5.2 Cost optimization
After having set the level of nutrients i.e. feed specification that
achieves the desired performance, the nutritionist must find the right
combination of ingredients at the lowest cost. To do so, a least cost
formulation will be performed where available ingredients and their
actual price will be combined to get the optimized feed.
This combination of feed specification as for example digestible lysine
level and the price of the different ingredients like wheat, soybean
meal and L-lysine commercial product will lead to the optimal
incorporation rate of supplemental lysine in the feed. Therefore the
incorporation rate of amino acids within a feed is strongly influenced
by the price of the amino acids themselves but also by the other ingredients.
As a consequence there is no fix supplementation rate of
amino acids over time as nutritionist recalculate on regular basis the
optimal feed mixture. Amino acids are considered as a powerful cost
effective tool by the animal production industry.