Continuous submarginal phosphorus with broilers and the effect of preslaughter transportation: carcass defects,...

Broiler males were given a series of feeds from 0 to 8 wk having all nutrients advocated by the NRC (1984) and were compared with birds offered feeds with available P continuously 10% below recommendation. At termination, birds in pens were divided for cooping, and coops were either subjected to 6 h of truck transportation and 4 h of preslaughter rest or held stationary for 10 h. High summer temperatures existed throughout experimentation, and low dietary P reduced body weight gain through the first 6 wk, whereas an advantage in feed conversion and mortality occurred from 6 to 8 wk. Weight loss increased when birds were subjected to transportation, regardless of P nutriture, and a portion of the loss was recovered during processing as gain in relative chilled carcass yield. Proportions of abdominal fat and skinless boneless meats from chilled carcasses were unaltered, regardless of treatment. Increased incidence of deformed drumsticks occurred because of low P as did drumstick bruising, which was further accentuated when birds had been transported. Back bruising was prominent when P was adequate and birds were held stationary, whereas the converse occurred with transportation. Tibia length was reduced as a consequence of low P, whereas the femur suffered in terms of decreased mineral density at the epiphyses and resistance to Instron-applied stress. Although transportation in itself did not affect any bone measurement, inadequate P weakened the skeleton to increase likelihood of carcass defects during preslaughter stress.