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Predicting processing weights and broiler economics with productive energy (Arkansas Net Energy)

Martinez, D., N. Suesuttajit, C. Umberson and C. Coon

Nutritionists need an energy system to enhance feed formulation and impact broiler sustainability and economics. This study developed models for the growth rate of processing weights (carcass, breast fillet, tenderloins, wings, leg quarters), carcass mar-ket value gain (MVG), and gross profit gain (GPG) of broilers. 96 floor pens (20 chicks each) were assigned to one of 12 treatment diets (within 8 blocks), which consisted of changing levels of total digestible amino acids (TDAA; 1-3) or TDAA and digestible starch (4-6), or increasing (7-9) or reducing (10-12) diet density. Blocks initially received a standard diet, followed by consecutive weekly treatment periods, one block at a time. Feed was restricted to ensure similar energy intake. Feed intake was recorded. Body energy gain (NEg) and weights of each processing part were determined with dual-energy X-ray absorptiometry, and heat production (NEm, fasting) in calorimetry chambers. Diet N-corrected apparent metabolizable energy (AMEn) was determined, and CNE (AMEn – heat increment) and PE (NEg + NEm) were calculated. MVG was calculated with the market price of each part, and GPG was the difference between MVG and daily feeding cost. One-way ANOVA (12 treatments, 8 blocks, and 1 replication per block) and Tukey tests, along with linear mixed modeling, were used to analyze the data in JMP. MVG and GPG data was Ln-transformed. The growth rate of all processing parts, MVG, and GPG were positively influenced by TDAA (P<0.05). PE (not AMEn or CNE) efficiency to produce carcass or breast gains showed no change among treatments (P>0.05). AMEn and CNE showed no influence on the growth rate of processing parts (P > 0.40 and 0.06, respectively), MVG (P = 0.66 and 0.13, respectively), or GPG (P = 0.10 and 0.13, respectively). Simple linear models were validated to predict the growth rate of processing parts (adjR2 > 0.97), MVG (adjR2 > 0.99), and GPG (adjR2 > 0.98). The PE model for MVG indicated that per each continuous +100 kcal/kg diet PE, each 56-d-old bird gained +3.53 cents of market value ($35,000 per million birds produced).

In conclusion, PE is a strong predictor of processing weights, carcass market value, and gross profit. Models were developed to predict these traits based on PE.