ARTICLE FEED & ADDITIVE MAGAZINE December 2022 57 The nutrient density in this trial was increased by the addition of soybean oil and/or FRA® LeciMax Dry. For each energy level, the nutrient density increased by 3.0% when adding FRA® LeciMax Dry on top confirming the higher nutrient availability. The broiler performance tended to be higher with a higher nutrient density. Following the law of diminishing returns, a decrease in marginal performance with the highest energy level was expected. However, as the results show this was not the case indicating that the maximum performance was not yet obtained within this nutrient density range. Furthermore, as the nutrient density increased, gross income decreased. This is shown in Figure 1, where increasing the nutrient density solely by increasing the SBO levels resulted in a decrease in gross income per broiler. However, when lysolecithins were added, both nutrient density and performance increased because of higher energy and amino acids availability. This resulted in a higher economic output than with SBO alone. However, the extra benefit of FRA® LeciMax Dry decreased with T6 as compared to T2 and T4 even though T6 yielded a higher performance. This can be explained by the law of diminishing returns in which marginal returns become smaller as nutrient density increases. This trial showed that it is more profitable to increase nutrient density with a combination of SBO and FRA® LeciMax Dry instead of SBO alone. Despite the fact that a maximum performance was not reached as indicated by the significant growth difference between T5 and T6, this was not the case for the gross income per broiler as Figure 2 shows. Based on the circumstances of these trial and the trial data, the maximum economical return would be obtained at a nutrient density of 146 with the addition of FRA® LeciMax Dry. This means that the energy level of this typical diet only can be increased by a level between 25 and 100 kcal/kg when FRA® LeciMax Dry at 500 g/ton is added to obtain the highest profit. In conclusion, this trial confirmed that increasing nutrient density leads to improvements in growth performance and FCR but only to a certain point due to the limited capacity of broilers to utilize high-dense diets. After this point, it is necessary to add a digestive enhancer like lysolecithins to further optimize the feed utilization. Moreover, this trial showed that it is economically more interesting to add FRA® LeciMax Dry on top than adding more soybean oil in order to increase nutrient density, following the concept of “minimum nutrition”. This enables a higher nutrient efficiency while maintaining growth performance. Figure 1. The effect of nutrient density on gross income when only soybean oil (SBO) or both SBO and FRA® LeciMax Dry are added to increase nutrient density Figure 2. The quadratic relation of nutrient density and gross income when soybean oil and FRA® LeciMax Dry are added to increase nutrient density
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