An experiment was conducted using 96 individually caged male broilers between 49 and 77 d of age. One objective was to establish phenotypic relationships between some production traits [feed conversion ratio (FCR), feed consumption, residual feed consumption (RFC), relative weight gain (RWG), weight gain (WG) and live weight (LW)] and “tissue retention efficiency” (TRE) traits in a slow-growing broiler population. The other objective was the characterization of Campero-INTA broilers for TRE traits. Weight and feed consumption were recorded weekly. Forty four broilers were slaughtered at 44 d of age to estimate initial body composition while the remaining birds were slaughtered at 79 d of age. Ether extract and crude protein content of the carcasses were used to estimate TRE traits: Energy retained as protein (ERP), energy retained as fat (ERF), ERP/(ERP+ERF), ERF/(ERP+ERF), protein retention efficiency and lipid-protein ratio. Correlation coefficients between traits were obtained and regression analyses were done for the evaluation of the influence of production traits on TRE traits. The independent variable that best explained ERF was WG (R2 = 0.49). Inclusion of final LW and RWG raised the R2 to 0.58 and decreased the error term. The ERP was best explained by RWG (R2 = 0.37); lipid-protein ratio by final LW (R2 = 0.49); protein retention efficiency by FCR (R2 = 0.34) and fraction of retained energy (ERF-ERP/ERP+ERF) by WG (R2 = 0.29). The TRE traits were not well predicted by the measured production traits. The high phenotypic variability observed in some of the TRE traits suggested a need for further studies on these characteristics.
"Experientia docet" - Experience is the best teacher