Study of optimum ratio of calcium and available phosphorus when removing supplemental phosphorus from finishing diet on broiler performance and leg disorders
1998
Mananya Boonyoung
Research was conducted in order to elucidate the effects of the supplemental phosphorus removal from broiler finishing diets on broiler performance. carcass traits, leg disorder percentage and production cost. The study was divided into 2 experiments (35-42 days of age and 42-49 days of age, respectively). In each experiment, four hundred and fifty straight-run Arbor Acre broilers were divided into 5 dietary treatment groups. Each group consisted of 6 replicates with 15 birds each. The dietary treatments were (1) the control with oystershell and dicalcium phosphate supplementation and had the calcium : nonphytate phosphorus (Ca : NPP) ratio at 2:1, (2) the total removal of oyster shell and dicalcium phosphate from the basal diets; (3) the total removal of dicalcium phosphate from the basal diets and supplemented oyster shell in order to have Ca : NPP ratio at 1:1; (4) the total removal of dicalcium phosphate from the basal diets and supplemented oyster shell in order to have Ca:NPP ratio at 1.5:1; and (5X the total removal of dicalcium phosphate from the basal diets and supplemented oyster shell in order to have Ca:NPP ration at 2:1; All the diets were isonitrogenous and isocaloric. No significant difference were found among dietary treatments on weight gain, feed intake, feed gain ratio, percent mortality, percent leg disorder, percent bone ash, and carcass quality. Total oyster shell and dicaldium phosphate removal from the finishing diets, however, were found (P.05) to decrease both calcium and phosphorus levels in the tibia bone. Oyster shell supplementation to adjust Ca : NPP ratio from 1:1 up to 2:1 improved (P.05) calcium levels in the tibia bone. The response of oyster shell supplementation on phosphorus levels was profounded by the age of the broilers. Phosphorus levels were not different from the control in birds aged 42-49 days when oyster shell had added to make the Ca : NPP ratio from 1:1 to 2:1. However, this effect was not found in younger birds (35-42 days.)
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