Growth performance and spontaneous bone fracture incidence of turkey toms fed various levels of calcium and nonphytate phosphorus to heavy market weight

This trial evaluated the effects of various dietary calcium and nonphytate phosphorus (nPP) feeding regimens on the growth and bone integrity of Nicholas 700 toms from 2 to 19 wk of age. After a 2-wk common brooding period, 24 to 25 poults/pen were allocated to 8 pens/treatment. Crumbles were fed from 2 to 5 wk of age and pellets were fed from 5 to 19 wk of age in a 3-wk phase program. Dietary calcium was kept at a 1.8:1 ratio with nPP for all diets. Diet 1 (LOW) was formulated to provide NRC recommendations for each phase change, ending with 0.25% nPP from 17 to 19 wk of age. Diet 2 (MED) nPP levels averaged 0.06 percentage units higher than the LOW diet. Diet 3 (HIGH) averaged 0.10 percentage units higher nPP than the MED diet. Diet 4 (VHIGH) averaged 0.10 percentage units higher nPP than the HIGH diet. Body weight was decreased (P < 0.01) by the LOW diet compared with all other treatments throughout the trial. By 8 wk of age, BW was lower (P < 0.001) when the MED diet was fed compared with the HIGH and VHIGH diets. Feed:gain was worsened (P < 0.02) by the LOW diet, compared with the HIGH and VHIGH diets, throughout the entire trial. The incidences of leg problems and spontaneous bone fractures were increased (P = 0.001) when the LOW diet was fed compared with the other diets. The increase in litter phosphorus (P = 0.001) was directly proportional to increases in dietary nPP. The HIGH and VHIGH diets resulted in the best growth performance and skeletal integrity.