CONTINUOUS SUBMARGINAL PHOSPHORUS WITH BROILERS AND THE EFFECT OF PRESLAUGHTER TRANSPORTATION - CARCASS DEFECTS, FURTHER-PROCESSING YIELDS,AND TIBIA-FEMUR INTEGRITY

Broiler males were given a series of feeds from 0 to 8 wk having all n utrients advocated by the NRC (1984) and were compared with birds offe red feeds with available P continuously 10% below recommendation. At t ermination, birds in pens were divided for cooping, and coops were eit her subjected to 6 h of truck transportation and 4 h of preslaughter r est or held stationary for 10 h. High summer temperatures existed thro ughout experimentation, and low dietary P reduced body weight gain thr ough the first 6 wk, whereas an advantage in feed conversion and morta lity occurred from 6 to 8 wk. Weight loss increased when birds were su bjected 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 meat s from chilled carcasses were unaltered, regardless of treatment. Incr eased incidence of deformed drumsticks occurred because of low P as di d drumstick bruising, which was further accentuated when birds had bee n transported Back bruising was prominent when P was adequate and bird s were held stationary, whereas the converse occurred with transportat ion. Tibia length was reduced as a consequence of low P, whereas the f emur suffered in terms of decreased mineral density at the epiphyses a nd resistance to Instron-applied stress. Although transportation in it self did not affect any bone measurement, inadequate P weakened the sk eleton to increase likelihood of carcass defects during preslaughter s tress.