FEED Business Worldwide - October / November, 2011
 
Variability in the feeding value of Indonesia's corn harvest
 
by Dr Alexandre PÉRON, Technical Services Manager, Danisco Animal Nutrition, Singapore
 
 
With current high ingredient prices and feed shortfalls, better utilisation of corn becomes more important than ever. Corn quality depends on a complex interaction between both intrinsic and extrinsic characteristics of the grain.
One major intrinsic factor is that crops with different genetic backgrounds exhibit variations in nutrient content. For example, corn's protein and amino acid content can vary, as can its starch composition. Because of this, the amylose/amylopectin ratio and starch granule particle size distribution can differ. Differences also occur in the levels of anti-nutritional factors such as phytate.
 
Extrinsic factors such as growing, storage and processing (drying) conditions also influence corn quality through changes in the endosperm starch/protein matrix. Ultimately, the feeding value of corn appears to be primarily driven by starch utilization, as corn starch supplies around one third of the total metabolisable energy of a poultry diet (Péron & Gilbert, 2010).
 
 
Monitoring corn quality
 
Danisco's Avicheck™ Corn service was developed to measure the key parameters that influence corn feeding value for poultry and quantify the additional energy that can potentially be released by the addition of Danisco's enzyme solution, Avizyme® 1502 (xylanase, amylase and protease) to corn-based diets.
 
Through extensive research, Danisco has identified several parameters that influence the degree to which this unique enzyme combination can improve the energy digestibility of corn. This Energy Improvement Value (EIV) is influenced by a variety of factors.
 
These factors include starch, protein and oil content, as well as in-vitro starch digestibility and protein solubility index. The protein solubility index is particularly important as it provides an indication about the degree to which protein binds with other nutrients in corn, especially starch. Experience in using the Avicheckâ„¢ Corn service has shown that the EIV can be a good indicator of the nutritional value of corn for poultry.
 
 
Regional differences
 
Recent analyses of 66 corn samples collected throughout Indonesia over the past two years have revealed some interesting trends about the parameters influencing variability in the nutritional value of this cereal grain. The survey revealed that the quality of Indonesian corn remained very consistent between the 2009 and 2010 harvest years, as shown by the average nutrient content and EIV (Table 1). The feeding value of Indonesian corn appears to be well within the worldwide average (EIV=158.5 kcal/kg, n=1608 samples collected between 2006 and 2009).
 
 
However, when the analytical results were sorted according to growing location, significant differences became apparent (Table 2). While starch and oil content remained fairly consistent across regions, corn samples from the Lampung area showed slightly lower protein content. Compared with the overall results (Table 1), corn samples from Jawa Timur and Sulawesi could be described as having a higher intrinsic nutritional value, as indicated by their relatively low EIV.
 
At the other end of the scale, corn samples from Lampung showed the highest EIV and therefore, the lowest intrinsic nutritional value with a greater potential for enzyme response. This may be partly due to their lower protein content but it is more likely related to the quality of these proteins.
 
 
Further analyses carried out on representative corn samples from both growing locations showed that the difference in grain feeding value between Jawa Timur and Lampung samples was mainly driven by the difference in protein solubility index (Table 3). Corn from Lampung exhibited a lower and more variable index than corn from Jawa Timur; 13.2 (CV=12.3 %) versus 30.1 (CV=4.7%).
 
All samples collected in the Lampung area were mechanically-dried, as opposed to samples from Jawa Timur, which were naturally sun-dried. In recent years, research has shown that heating of corn by mechanical drying makes its protein less soluble and increases starch/protein binding, leading to reduced starch accessibility and subsequent lower AME of corn (Iji et al., 2003; Kaczmarek et al., 2007). Indications of this have also been found when using the Avicheckâ„¢ Corn service to assess the quality of the North American harvest.
 
As reported by Hruby (2010), many parts of the US had a late spring in 2009, followed by a wetter and cooler growing and harvesting season. In order to reduce the backlog of late-harvested, high moisture corn, the crop was subjected to very high drying temperatures.
 
 
As a result of this harsh drying process, grain samples from 2009 exhibited a lower and more variable protein solubility index (average=11.1, CV=65%) than the 2008 corn harvest (average=23.7, CV=14.6%). These differences were also associated with a significantly higher EIV (i.e. lower intrinsic nutritional value) for the 2009 crop.
 
 
Key to success
 
The use of exogenous feed enzyme technologies, such as a carefully selected balance of xylanase, amylase and protease in Avizyme 1502, in association with analytical tools and prediction models, can help the nutritionist to extract maximum nutritional value from feed and achieve more consistent bird performance.
Based on the economic model included in the Avicheckâ„¢ Corn service, it is possible to calculate the financial benefits associated with the use of Danisco's enzyme solution. Using the average EIV of 154.5 kcal/kg for 2010 corn samples, and assuming a 50% inclusion of corn in the formulation, the Avizyme 1502 enzyme combination provides the opportunity to contribute an additional 77 kcal ME per kilogram of feed. This equates to a potential net feed cost savings of up to us$7/tonne of feed.
 
 
References
 
Péron. A. and Gilbert, C. (2010) Poultry Feed Quality Conference, Kuala Lumpur, Malaysia.

Hruby, M. (2010) Feedstuffs 82:4.

Iji et al. (2003) Reproduction Nutrition Development 43: 77-90.

Kaczmarek et al. (2007) British Poultry Abstracts 3: 20-21.
 
 
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