1. The objective of this work was to determine the effect of slaughter age and stunning method on the quality of turkey meat from poultry processing plants. 2. One hundred B.U.T. Premium turkeys were divided into 4 groups of 25 animals according to slaughter age (15 or 17 weeks) and CO stunning procedure (G1 stepwise: step1: 30% CO, 15 s; step 2: 55% CO, 40 s; step 3: 70% CO, 45 s; G2: progressive increase of the CO concentration at a rate of 0.8% per s for 100 s). The quality of the breast meat was determined in fillets taken at different post-mortem times. 3. There were differences between the stunning groups for several variables (pH: 6.01 ± 0.01 and 5.95 ± 0.02; a*: -1.84 ± 0.05 and -2.21 ± 0.04; b*: 4.99 ± 0.15 and 4.68 ± 0.16; drip loss: 0.85 ± 0.02 and 0.71 ± 0.02 for G1 and G2, respectively), while no significant differences were found for L*, cooking loss and texture analysed with a Warner Bratzler Shear Force cell (WBSF). 4. Slaughter age had a significant effect on all the parameters studied (pH: 6.01 ± 0.01 and 5.95 ± 0.01; a*: -2.21 ± 0.05 and -1.88 ± 0.05, b*: 5.50 ± 0.17 and 4.42 ± 0.15; drip loss: 0.71 ± 0.02 and 0.86 ± 0.02, cooking loss: 12.56 ± 0.22 and 14.69 ± 0.16 for turkeys slaughtered at 15 and 17 w, respectively) except on L* and WBSF. 5. The ageing of the meat affected pH, colour values, drip loss and WBSF, with differing degrees of evolution: mean values of L* (39.36 ± 0.35. 45.77 ± 0.20 and 46.30 ± 0.24, for 20 min, 24 h and 7 d post mortem, respectively) and drip loss (0.75 ± 0.03 and 0.84 ± 0.02 for 24 h and 7 d post mortem, respectively) increased, those of a* (-1.77 ± 0.08, -1.94 ± 0.07 and -2.22 ± 0.05 for 20 min, 24 h and 7 d post mortem, respectively) and WBSF decreased (3.73 ± 0.06 and 2.63 ± 0.04 for 24 h and 7 d post mortem, respectively), those of pH decreased in the first 24 h and remained stable for the next 6 d (6.19 ± 0.02, 5.87 ± 0.01 and 5.88 ± 0.01), and those of b* increased in the first 24 h post-mortem and remained stable for the next 6 d (3.26 ± 0.31, 5.86 ± 0.16 and 5.47 ± 0.08). 6. The results revealed no critical differences between stunning methods, and suggest that animals slaughtered at 15 weeks present higher quality meat than those slaughtered at 17 weeks.

1. The objective of this study was to evaluate the effect of sex and gas stunning on quality attributes of turkey breast meat. 2. One hundred B.U.T. Premium turkeys (50 males and 50 females) were divided into four groups of 25 animals and subjected to one of two CO stunning procedures: G1 stepwise (step 1: 30% CO, 15 s; step 2: 55% CO, 40 s; step 3: 70% CO, 45 s) or G2 fixed concentration (80% CO, 100 s). The pH and meat colour at 20 min post-mortem, and pH, colour (L*, a*, b*), water holding capacity (WHC), drip loss (DL), cooking loss (CL) and Warner-Bratzler shear force (WBSF) in breast samples at 24 h and 7 d post-mortem were assessed. 3. There were significant differences between stunning groups for pH, meat colour and CL, whereas no significant differences were found for DL and WBSF. Sex had a significant effect on pH and b* and ageing of meat affected pH, colour coordinates, DL and WBSF. 4. It was concluded that the G2 treatment affected negatively the pH value and colour coordinates. However, G2 stunning affected positively the WHC parameters. Female turkeys had better results than males for pH, and the colour of female turkey breast meat was less yellow than male breast meat.

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