Productive energy (PE) caloric values of nutrients in soybean meal (SBM), corn, and diets for broilers were determined with 5 experiments (E1 to E5) from 1 to 56 d. E1 to E4 determined corn PE, were fed pelleted diets in 5 feeding phases, and their diets included SBM dilutions with cellulose or corn, and levels of oil or total digestible amino acids (TDAA). E5 determined PE of SBM and diets, and used 96 pens assigned to 1 of 8 blocks. Pens in each block were restricted-fed one of 12 treatment mash diets for one week. E5 treatments varied in TDAA, dCP, dFA, dST, and non-starch polysaccharides (NSP). Fresh birds were used in each feeding phase (E1 to E4) or block (E5). Response variables: In E1 to E5, BW gain (BWG), feed intake (Fl), and feed conversion ratio (FCR) were recorded. Body composition and processing weights were measured with Dual Energy X-Ray Absorptiometry; fasting heat production (FHP) with calorimetry chambers. PE (kcal/kg) was: PE = net energy (NE) gain (NEg) + NE maintenance (NEm; FHP = NEm). In E5, market value gain (MVG; cents/bird/d; = processing weights X prices) and gross profit gain (GPG; cents/bird/d; = MVG – feeding cost, cents/bird/d) were also calculated. Stats: ANOVA and Tukey test compared treatments and mixed models were fitted in JMP. Results of E1 to E4: dST, dCP, and dFA explained 72.8, 20.8, and 6.4% of corn PE. Corn PE (kcal/kg) = 136.5 +80.55 dCP +65.29 dFA +35.49 dST –13.66 age –0.454 (age –31.1548) (R²=0.62). Results of E5: dCP and TDAA explained 92% and 88% of diet NEg, 85% and 81 % of diet PE, and 96% and 96% of SBM PE, respectively. SBM PE = [504 +60 dCP +29 dFA +31 dCP/NSP (R²=0.58; 98% accurate)] or [462 +68 TDAA +36 dFA +37 TDAA/NSP (R²=0.57; 98% accurate)]. Diet PE = 562 +81 TDAA +35 dFA (R²=0.80). CP, TDAA, and dFA favored BWG (P≤0.019) and FCR (P<0.014). dCP and TDAA favored protein gain (P<0.010), but dFA provided no additional predictive ability (APA; P=0.858). dST provided no APA for BWG, FCR, or PAC (P=0.139). PE predicted BWG, FCR (P<0.001), and PAC (P<0.017). Models for MVG or GPG, both including PE intake (kcal/bird/d) and the PE/TDAA intake ratio, showed positive signs for PE intake (P<0.001) and negative signs for PE/TDAA (P≤0.001), implying that MVG and GPG increase when PE comes from amino acids. Overall results: PE caloric coefficients (kcals predicted per g of nutrient) were obtained. Corn: 7.5, 6.1, and 3.2 kcal per g of CP, FA, and starch, respectively. SBM: 7.9, 7.3, and 3.9 kcal per g of TDAA, dCP, and dFA, respectively. Diet: 10.5, 9.6, and 4.7 kcal per g of TDAA, dCP, and dFA, respectively. In conclusion, amino acids are the main PE driver. Protein calories are more valuable than other nutrients for meat gain, carcass value, and profit.

Martinez, D. and C. Coon. 2025. Productive Energy Caloric Values of Protein and Fat in Soybean Meal, Corn, and Diets for Broilers. 2025 Poultry Science Association Annual Meeting, Abstract 304