ELEVATED PLASMA-CORTICOSTERONE CONCENTRATIONS INFLUENCE THE ONSET OF RIGOR-MORTIS AND MEAT COLOR IN BROILERS

This experiment was conducted to determine the effect of elevated plas ma corticosterone (CORT) levels on meat quality characteristics. Male broilers (Arbor Acres) were either 1) fed diet containing corticostero ne (CORT) prior to processing, 2) transported by truck for 3 h before processing, or 3) processed without either of the above treatments. Si x crates of birds (10 birds per crate; two crates per treatment) were stunned or killed using CO2 gas. Six birds per crate were processed an d blood samples were collected during exsanguination for plasma CORT a nalysis. Meat samples were collected from carcasses either at 20 min o r at 4 h post-mortem. At each sampling time (ST), Pectoralis superfici alis samples were collected and either individually quick frozen (IQF) in liquid nitrogen or aged on ice (AOI) for 24 h prior to pH, ratio o f inosine to adenosine nucleotides (R-value), cooking loss, shear valu e, and color analyses. The IQF Biceps femoris samples were used for pH , R-value, color, and heme pigment analysis. Mean (+/-SEM) CORT concen trations were 12.9 +/- 2.57, 11.7 +/- 1.38 and 7.9 +/- 0.79 ng/mL, res pectively, in the CORT, transported, and control groups. There were si gnificant treatment by ST (P < 0.05) and ST (P < 0.001) effects on the R-value of IQF P. supeuficialis samples. The CORT group had the highe st L value (P < 0.01) and the lowest a* value (P < 0.06). There was a lso a significant main effect of ST on shear values (P < 0.05) of AOI P. superficialis samples, with the means higher at 4 h than at 20 min post-mortem. The R-value of IQF B. femoris samples was markedly influe nced by treatment (P < 0.001) and ST (P < 0.001). The results indicate that artificially elevating circulating CORT concentrations results i n lighter meat color in broilers.