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Productive energy (Ark NE), apparent metabolizable energy (AMEn) and net energy (NE) values for diets and ingredients for 5-56d broiler grow-out studies

Suesuttajit, N., J. Weil, C. Umberson, D. Martinez, A. Scott and C. Coon

Arkansas net energy (Ark NE) is a productive energy system based on actual dietary energy utilized for gain and maintenance. A total of 48 diets with varying levels of total digestible amino acids (TDAA), digestible starch (DSTAR), digestible fat (DFAT), and NSP were utilized in 5-56d broiler studies to determine the performance and energy value of diets and ingredients using DEXA and indirect calorimetry system. Data were subjected to a one-way ANOVA and Tukey’s HSD to compare separate treatment means with significance set at 0.05 using JMP pro16. Multiple linear regression models were computed to generate prediction equations for the energy values of ingredients. Treatment diets significantly impacted broil- er performance, ADG, and FCR. FCR provided a much stronger negative relationship to Ark NE (R2 = 0.52) compared to AMEn (R2 = 0.16) and classic NE (R2=0.17). The TDAA, DFAT, and DSTAR were positively re- lated to Ark NE (P<0.05), while total NSPs negatively affected Ark NE for 56d broiler performance. Each percentage increase of TDAA, DFAT and DSTAR increased the predicted Ark NE value by 74, 58, and 32 kcal/kg, respectively, while increase of NSP decreased the predicted Ark NE value by 18 kcal/kg in the multiple linear regression model. Conversely, AMEn and classic NE systems were strongly influenced by DFAT compared to TDAA and DSTAR in the same diets. The average energy efficiency (EE) of Ark NE compared to AMEn (Ark NE/AMEn) was 85.48% and the EE of classic NE compared to AMEn was 75.49% for the same diet. The predicted Ark NE values of SBM, corn, and corn oil were 3340, 2511, and 5,728 kcal/kg for 56 d broiler performance, respectively.

The studies indicated digestible amino acid calories are the most important calories in 56d broiler grow-out because digestible amino acids enhance performance and contribute more calories for productive energy, whereas digestible dietary protein and amino acids decrease AME and classic NE calories. The AME and classic NE systems undervalue protein ingredients such as soybean meal and overvalue energy sources such as corn oil and corn. The AMEn and classic NE energy systems are less sensitive to broiler performance and type of gain compared to Ark NE.