Cross relationships between growth performance, growth composition and feed composition in broiler chickens, calculated from published data

ABSTRACT The study presented here used experimen-tal data obtained from 42 articles to calculate the cross relationships between daily feed intake (DFI), feed com-position (AMEn and CP), BW, daily weight gain (DG), mean age (A), and composition (FCG and PCG; fat and protein, respectively) of growth in broilers. All of the experiments selected were conducted at standard tem-perature and with ad libitum feeding. The articles in this database were published from 1980 to 2015, and represented a total of 12,277 broilers, 57 trials, and 384 basic treatments. Data ranged from 3 to 66, 0.077 to 3.322, 7.10 to 15.37, and 7.3 to 35.0 for A (d), mean BW (kg), AMEn (MJ/kg) and CP (%), respectively. Equations were established from regression calculations to calculate daily heat production as a function of BW, daily AME intake (MEI) as a function of BW, DG, FCG and PCG, PCG as a function of A and FCG, and FCG as a function of BW, protein efficiency (PE), AMEn, and CP. The combination of these equations expressing MEI, PCG, or FCG with equations express-ing the definitions of PE, AME (from AMEn), and DFI (from MEI) constituted a system of 6 equations which could be used to determine DFI values from the val-ues of AMEn, CP, A, BW, and DG. Using the values of AMEn, CP, A, BW, and DG from the database, the DFI values calculated with this system of equations showed a reasonable correlation with the DFI values measured (R2 = 0.880). This system of 6 equations yielded val-ues for DFI, PE, PCG, and FCG that were in agree-ment with the classical effects produced by increased CP values, or by reduced fat deposition associated with genetic selection for leanness. This system of 6 equa-tions might thus be considered an interesting frame-work for future nutritional modelling systems. Regres-sions predicting feed efficiency as a function of AMEn, CP, DG, and BW, or as a function of AMEn, FCG, DG, and BW showed R2 values of 0.767 and 0.747, respectively