Effects of certain pre-slaughter factors on stress responses and meat quality characteristics in broilers

Experiments were conducted using commercial male broiler chickens to study the effects of fasting, handling, crating, transportation and shackling on animal welfare and meat quality. Birds handled either singly or in groups of three in an inverted position for 2 min had higher plasma corticosterone (CORT) levels than birds held gently with both hands in an upright position (p {dollar}<{dollar} 0.05). CORT levels peaked at 3 h after handling or handling plus crating (p {dollar}<{dollar} 0.05). Repeated handling during growth did not decrease the CORT response to the different handling treatments at 7 weeks of age. CORT levels were highest immediately after the handling treatments were imposed.; The influence of different crating periods before or after 3 h of transportation was also studied. CIE LAB color coordinates (L{dollar}sp*{dollar}, a{dollar}sp*,{dollar} b{dollar}sp*,{dollar} chroma and hue angle) were measured on meat samples. Thigh meat samples from the 3 h crating group had the highest L{dollar}sp*{dollar} and Hue (p {dollar}<{dollar} 0.01) values and the lowest a{dollar}sp*{dollar} value. The CORT level was also the highest in the 3 h crating group. Holding crated broilers for 4 h after 3 h transportation resulted in lower CORT levels (p {dollar}<{dollar} 0.01) and lower thigh meat initial pH (p {dollar}<{dollar} 0.01). There was also a significant correlation between CORT and Hue values of thigh meat (r = 0.302, p {dollar}<{dollar} 0.01). CORT levels were then elevated by feeding broilers a diet containing CORT at a dose of 15 ppm. Breast and thigh meat samples were obtained at either 20 min or 4 h postmortem. Breast samples of the CORT fed group had higher L{dollar}sp*{dollar} (p {dollar}<{dollar} 0.01) and lower a{dollar}sp*{dollar} values. Thigh samples from the CORT fed group also had the lowest R-value (p {dollar}<{dollar} 0.001) at 20 min.; The effects of pre-slaughter shackling were then studied. CORT levels increased (p {dollar}<{dollar} 0.001) with increasing shackling times, ST (0, 2, and 4 min). ST influenced the b{dollar}sp*{dollar} (p {dollar}<{dollar} 0.01), chroma (p {dollar}<{dollar} 0.01) and Hue values (p {dollar}<{dollar} 0.05) of breast fillets. The results of these studies indicate that fasting, handling, crating, transportation and shackling increase CORT levels in broilers and that stress could produce paler meat.