Evaluating Alternative Feed Ingredients in Broiler Diets

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                                                     67 Wessel’s Road, Rivonia
                                                     P O Box 48 Rivonia 2128 South Africa
                                                     Tel: (011) 803-2050 Fax: (011) 803-8201
                                                     E-mail: rick@spesfeed.co.za




  Evaluating Alternative Feed Ingredients in Broiler
                         Diets

                        Rick Kleyn, SPESFEED (Pty) Ltd

As our poultry production systems become more intensive and more competitive,
we continually need to evaluate what we are currently doing and explore new
opportunities. The use of the feed ingredients that we use is and will always be
important to the nutritionist and the use of alternative feed ingredients
represents what is possibly the greatest opportunity for nutritionists and
poultry producers. It is true however that any feed is only as good as the
ingredients that are used in its manufacture.

Before any decision with regards an ingredient can be made, it is essential that
the nutritionist knows everything there is to know about it. This means that the
nutrient content should be known; that the physical structure or form of the
ingredient is correct; that the processing has been such that the nutrient bio-
availability has not been negatively impacted; and that the biological quality of
the ingredient in terms of any possible pathogen or toxin contamination can be
assured.

Once satisfied that you have complete knowledge of an ingredient, the economic
value of the ingredient can be determined. Traditionally, there are three
aspects that determine the value of an ingredient, these being; the price and
nutrient content of the ingredient itself; the price and availability of the other
ingredients; and lastly the diet in which it is to be used. By making use of the
ranging/sensitivity features of a standard feed formulation program it is easy
to determine the value of any ingredient in any specific product. By extension,
Multi-Mix® (Format International) technology gives the nutritionist the ability
to determine the value of an ingredient across a whole range of products.

Evaluating ingredients using standard feed formulation programs does have a
major shortcoming. LP generates a „least cost‟ diet for a certain pre-determined
feed specification. It does not look at the overall profitability of the production
process. Opportunity may well be lost if the nutritionist ignores bird response
to nutrients, in particular nutrient density, and it is this aspect that needs to be
added to our methodology of evaluating an ingredient.
The determination of the energy level of poultry diets is perhaps the most
important decision that has to be made by the nutritionist. Energy contributes
approximately 60 to 70% of the cost of a broiler diet, making the selection of
an energy level that will maximise profit all-important. It is widely accepted that
nutrient requirements should be expressed in terms of grams of nutrient per
unit of energy contained in the diet. By deriving functions of broiler response to
energy density, it is possible to determine the optimum energy level of a diet.
Saleh et al. (2004) and Guevara (2004) have both studied the effects of
nutrient density on the modern broiler. A simple set of polynomial models was
fitted to the data of Saleh et al. (2004) (figure 1).

           2250                                                                1.85


           2200                                                                1.80
                                            y = -0.0019x2 + 0.0305x + 2.0853
                                                       R2 = 0.8898
           2150                                                                1.75
   grams




                                                                                      kg/kg
           2100                                                                1.70
                                                 2
                                       y = 5E-05x - 0.0153x + 1.8353
           2050                                 R2 = 0.9609                    1.65


           2000                                                                1.60
                  12.7 12.8 13.0 13.2 13.3 13.5 13.7 13.8 14.0 14.2
                                     ME (MJ/kg)




Figure 1: Response in body weight gain and FCR in male broilers to
incremental levels of nutrient density, after Saleh et al. (2004)



By making use of a standard feed formulation program, the ideal amino acid
profile as published by Lemme et al., (2004), standard ingredient costs and an
estimated value for a live broiler, it is possible to calculate the return at the
different energy densities. This can be seen in the “Standard” line in (figure 2).

Whilst this data is useful, it was determined using very low bird stocking
densities (10 birds/m2). The work of Berri et al, (2004) demonstrates clearly
that at higher stocking densities birds respond to nutrients, total lysine in this
case, in a different manner.        The consequences of this are that often
experimental data may not apply to commercial conditions. Where stocking
densities are higher the expected growth on lower density diets may well be
over-estimated.

It is of interest that Saleh et al. (2004) reported that there was no increase in
mortality or leg disorders when feeding high-density diets. Abdominal fat was
not adversely affected by increasing nutrient density when protein was
maintained in ratio to energy. Breast meat yield and percentage remained
constant as the nutrient density changed.

By making use of the data published by Saleh et al. (2004) and the same
iterative methodology as described above, it is possible to illustrate exactly how
ingredient availability or price will interact with nutrient density. To this end, it
was assumed that a) relatively cheap Sunflower Meal and b) relatively cheap Full
Fat Soya become available. The results of this evaluation (Figure 2) illustrate
that should sunflower be available, it may well pay the nutritionist to reduce
nutrient densities. On the other hand, should FFS become freely available, it
will pay to use more dense diets.




                    5000

                                                              FFS
                    4800    Sunflowe
                                                                                         2
                                                                                           + 168.49x + 4352.8
                            r                                               y = -16.535x 2
                                                                                       R = 0.8733
                    4600


                    4400                                                                2
    SA Cents/Bird




                                                                            y = -14.511x + 101.27x + 4518.3
                                                                                      R2 = 0.9444

                    4200     Standard
                                                                                  2
                                                                      y = -12.115x + 88.003x + 4042.6
                    4000                                                         2
                                                                                R = 0.9035


                    3800
                           12.7   12.8   13.0   13.2   13.3    13.5    13.7     13.8     14.0     14.2
                                                       ME (MJ/kg)



Figure 2: The return per broiler at incremental nutrient densities, for
standard diets (- -), diets including cheap sunflower meal, (_ _ _) and diets
including cheap FFS (___), using the data of Saleh et al., 2004.

The take home message from this short article is simple. Remember to take bird
performance and financial return into consideration when evaluating alternative
ingredients. If you assume a fixed feed specification you may well not be feeding
diets of optimum nutrient density.

A complete list of references is available from the author.

				
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