In previous Processing Tips, the effect of stress before slaughter on color of poultry breast meat was discussed. It was noted that birds exposed to stress before slaughter may yield abnormally pale or dark breast meat. Broilers experience preslaughter stress when they encounter an external stimuli or unsettling circumstances that are adverse or disruptive. The immediate response to the stress, among other things, is an increase in heart rate, a rise in blood pressure, and muscular tension. Many different factors cause preslaughter stress for broilers, such as cold or hot ambient temperatures, long transportation, physical exertion, and human contact. The remainder of this poultry tip will focus on stress incurred during transportation.
Transporting broilers may be stressful because of environmental temperatures, loading density, duration of transport, vibration and noise. It has been suggested that transportation may affect meat quality because of the broilers' hormonal and metabolic response to the stressor, with the resulting loss of body equilibrium. Fortunately, birds recover from stress relatively quickly, but even brief stress may account for varying meat quality. Preslaughter stress may affect the acidity, color and water binding properties of the meat. According to Lambooij (1999), there are several factors that affect broiler stress, meat quality and carcass contamination. These factors include poultry health, genetics, physical condition of broilers, management, and the catching crews. In his proceeding on ante mortem factors related to meat quality, Fletcher (1991) categorized
production factors that can lead to carcass (C) or meat (M) defects. These production factors are summarized in the following table.Table 1: Summary of poultry carcass (C) and meat (M) defects and their suspected area of origin during production. (Fletcher, 1991; with modifications).
By knowing the approximate source, it is much easier to control the conditions leading to the problem. In Europe, emphasis is being placed on limited transportation time and stricter production controls, partly due to animal welfare concerns. Since length of transportation does affect carcass and meat quality, as well as pathogen contamination, it may be time to focus more attention in this area.References:Fletcher, D. L., 1991.Ante Mortem Factors Related to Meat Quality. Proceedings of the 10th European Symposium on the Quality of Poultry Meat. Beekbergen, The Netherlands.
Lambooij, B., 1999. Contamination during transportation and stress. World Poultry Magazine, November. pp.44-45.
Northcutt, J. K. 1996. Discoloration of chicken or turkey breast meat. Processing Tip. January.
By Julie K. Northcutt, Extension Poultry Scientist
Poultry Tips - College of Agricultural and Environmental Sciences
The University of Georgia Cooperative Extension Service