Abstract
ABSTRACT Corn is the main energy feed used in broiler chickens rations in most countries. In the literature, there are indications that high density corn segregated in densimetric table contains higher value of metabolizable energy than the corresponding fraction of low density, but the reasons are not clear. This study was conducted to determine the metabolizable energy of different types of corn, segregated in densimetric table, for poultry. The corn types were selected by the texture of grain (flint, semi-dent and dent) and were planted in the same area. Semi-dent grain corn was used as standard, and the flint and dent grains were segregated in a densimetric table to separate 25% of the total as high density and 25% as low density. The flint, semi-dent and dent corn and the high and low density fractions of flint and dent corn were used in a metabolism assay with broiler chickens from 20 to 29 days of age, with 9 replicates, to determine the Nitrogen-corrected apparent metabolizable energy (MEn). The density of the different types of corn, measured as hectoliter weight, varied from 683 to 768 g/L for dent corn and from 778 to 802 g/L for the flint corn; the density of the unsegregated semi-dent corn was intermediate. MEn ranged from 3.109 to 3.194 kcal/g for dent corn and from 3.141 to 3.211 kcal/g for flint corn. MEn of the high density dent corn, 3.194 kcal/g, was higher (p<0.05) than that of the low density fraction, 3.109 kcal/g. Segregation of flint corn did not result in fractions with contrasting MEn values. For dent corn, segregation in densimetric table was effective, resulting in a fraction with improved MEn for chickens.
Highlights
Energy is recognized as the most expensive component of poultry diets and corn is the main source of dietary energy in many production systems in the world
In a previous study (Silva et al, 2011), it was observed that when corn was segregated in densimetric table, the high density fraction resulted in significantly increased nitrogen-corrected metabolizable energy (MEn) for chickens of different ages compared to the low density fraction
The metabolism assay was conducted in three repetitions; each repetition consisted of eight treatments and three replicates in a completely randomized experimental design; the treatments included the reference diet and seven test diets whose ME and MEn values were determined in order to calculate the energy values of the corn types
Summary
Energy is recognized as the most expensive component of poultry diets and corn is the main source of dietary energy in many production systems in the world. In a previous study (Silva et al, 2011), it was observed that when corn was segregated in densimetric table, the high density fraction resulted in significantly increased nitrogen-corrected metabolizable energy (MEn) for chickens of different ages compared to the low density fraction. Based on the above considerations, it was hypothesized that corn segregation in densimetric table may separate grains according to certain characteristics resulting in contrasting MEn for chickens. The improvement in MEn for the high-density corn determined by Silva et al (2011) was based on only one corn hybrid, which was produced especially for the study, but the reason for the difference in MEn values has not been pointed out. The present study was carried out to determine the MEn for poultry of corn types contrasting in endosperm texture (flint and dent) and segregated in densimetric table
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