Effects of crating and transport on stress and meat quality characteristics in broilers

Experiments were conducted to determine 1) whether different crating durations influence stress responses and meat quality in broilers, and 2) whether holding crated broilers after transport influences corticosterone (CORT) levels and meat quality. In a preliminary experiment, male broilers (n = 50) were held in crates (10 birds per crate) for either 0, 1, 2, 3, or 4 h prior to processing. Crating duration did not affect plasma CORT level, cooking loss, shear value of breast or thigh muscles, or carcass skin discolorations. Crating duration also did not affect the color (L*, a*, b*, chroma, and hue angle) of breast meat, but did change the color of thigh meat, with samples from the 3 h crating group having the highest hue values (P < 0.01). Corticosterone concentrations and hue values of thigh samples were positively correlated (P < 0.05, r = 0.244). In Experiment 1, broilers (n = 36) were crated for either 1 or 3 h, with 9 birds per crate. Crating time did not influence plasma CORT, epinephrine, or norepinephrine concentrations, initial pH, color, or texture of breast and thigh meat samples. In Experiment 2, broilers were crated (nine birds per crate) early in the morning and transported 3 h to the processing facility by truck. Nine crates of birds were held in a dark quiet place for 4 h prior to processing (H) and the remaining nine crates were processed immediately (NH). Corticosterone levels were significantly lower (P < 0.01) in the H group than in the NH group. Initial pH of thigh meat of the H group was also significantly lower (P < 0.01), although breast meat pH was not affected by treatment. Holding had no effect on shear values, color (breast and thigh), or total heme concentration (thigh). There was a significant correlation (P < 0.01, r = 0.302) between CORT levels and hue values of thigh meat. These results suggest that higher preslaughter stress levels in broilers could influence the color of thigh meat, although overall meat quality was not affected under the conditions of this study.