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By Marcus Kenny, Carolyne Kemp and Colin Fisher, Aviagen
Many years of selection of the Aviagen pedigree lines for growth, leg strength, metabolic fitness and breast meat yield have produced Ross broilers which are very responsive to dietary protein. Even at high growth rates increased protein levels give useful gains in growth, feed conversion and meat yield while still maintaining superb liveability.
The decision on what protein levels to feed a flock of commercial broilers is an economic one. To help inform such decisions, Aviagen’s team of nutritionists have evaluated the protein responses of Ross 308 broilers in an ongoing series of trials. The balanced protein project is directed towards producing a calculator which is based on this trial data. The calculator integrates local raw material prices and product values with an understanding of how Ross broilers respond, and explores the appropriate levels of dietary protein for broilers under local conditions.
The project has enhanced the nutrition team’s understanding of the biological responses of Ross broilers. It also enables us to help our customers get the most out of their Ross birds under local economic conditions, so maximising profitability.
Aviagen already publish recommendations for nutrient density for diets fed to broilers in the starter, grower & finisher period (below), accompanied by the warning that the nutrient levels will need to be adjusted to maximise profitability under local conditions. The values in the table summarise the ration described as the 100% or Manual diet.
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Starter
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Grower
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Finisher
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Age
Feed
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days
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0 - 10
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11 - 28
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29 - slaughter
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Energy
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Kcals
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3010
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3175
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3225
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Digestible
Lysine
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%
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1.27
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1.08
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0.88
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The balanced protein calculator offers a way to explore the necessary adjustments for local conditions and markets.
The unique and valuable part of the Aviagen protein calculator is the set of response data which have been derived from several trials carried out over the last two years. A total of 64 different responses have been collated, including feed conversion, liveability, eviscerated carcass, breast, drum and thigh meat yields and abdominal fat levels.
The calculator is shown diagrammatically below, summarising the outputs and inputs. Various pieces of information will be needed to use the calculator to explore the dietary amino acid level which will maximise profitability. Firstly, feed prices will need to be calculated for each range of diets, from 70% to 130% of manual protein level (levels of all other nutrients left unchanged). Diets should be formulated on the basis of true faecal amino acid digestibilities, using the ideal amino acid profile given in the Ross broiler manual. The revenue prices for live birds, eviscerated carcasses and carcass portions will also be needed, depending on the objective of the broiler growing business under examination.
Broiler Balanced Protein Calaculator
For example, breast fillet prices will not be of any relevance to a business which is selling all its production as whole, eviscerated carcasses. Fixed costs for growing and processing the birds are useful in generating realistic values. The protein calculator can then be used to calculate the margin at the farm gate (live, whole birds), after primary processing (eviscerated carcasses) and after secondary processing (portions or de-boned meat).
The Aviagen balanced protein calculator runs off an Excel spreadsheet. Margins are calculated for broilers at target weights of 1.7, 2, 2.5 or 3kg, and all the biological response data are based on fixed feed programmes for Starter, Grower & Finisher diets, with energy levels as recommended in the Ross broiler manual. Other management issues, which might have an impact on final weights, for example stocking density or house temperature, are not taken into account in this calculator.
Typical UK feed costs, live bird values and portion values show that the amount of dietary protein needed to maximise the profitability of the business varies depending upon whether the business is set up to sell live birds, eviscerated carcasses or portions.
To maximise profitability on live bird sales, a protein level equivalent to 100% of the Ross manual was required. Eviscerated bird margins were maximised at 106% of the Ross manual recommendations and portioned bird margins at 120%.
Alternative scenarios, examined for the same cost/revenue base, establish some interesting points of principle.
If for some reason the target kill weight is increased, the maximum margin for live bird production remains unchanged at a protein level of 100% of the Ross manual. The margins for eviscerated carcasses & portioned bird will however be maximised at a higher protein level as the target weight increases. Conversely, if feed prices increase across the range of nutrients, then the optimal amino density is unchanged for all products. Overall margins will of course be lower, but trying to reduce feed cost by lowering nutrient density will make the losses worse.
The situation changes if the marginal cost of balanced protein increases, as shown in the graph. This situation is likely to arise if the price of any of the protein raw materials increases, especially if the possible alternatives are limited. In this case, moving from 100% to 110% of the manual, which used to increase the diet cost by 5%, now increases diet costs by 10%. Under this situation, the optimal level of amino acids will be lower.
A case study examined the optimal amino acid densities in different parts of Europe. The countries were chosen to have different target weights, different final products and different relative protein costs. Under current market conditions, the results of the study showed a range of optimal protein levels for live bird production from 104% of manual (1.7kg target weight, relatively low marginal protein cost) to 95% of manual (2kg target weight, relatively high marginal protein cost).
To conclude, the Aviagen nutrition team have developed a method to summarise a body of information which consolidates the unique understanding of how the Ross broiler responds to inputs of balanced dietary amino acids., This information has been used to generate a protein calculator which, in co-operation with nutritionists working with our customers, enables dietary protein levels to be set to maximise the profitability of the business.
Courtesy of Poultry World, July 2004
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