Availability for poults of phosphorus from meat and bone meals of different particle sizes.

Two experiments were conducted to compare the dietary availability of P from meat and bone meal (MBM) with that of P from dicalcium phosphate (DP) for poults. Two batches of the same MBM were tested. The batches differed in fineness of grind; one was passed through a 10-mesh screen (openings of 2.03 mm) (MBM1O) and the other through a 12-mesh screen (openings of 1.91 mm) (MBM12). In Experiments 1 and 2, the low-P basal diets contained, by analysis, 0.54% P (0.2% nonphytate P) and 0.64% P (0.3% nonphytate P), respectively. Each batch of MBM and DP were included in isocaloric, equinitrogenous diets to obtain increments of 0.1, 0.2, 0.3, and 0.4% P added to the basal diet. Three pens, each containing seven poults, were assigned to each of the 13 dietary treatments. Poults were fed the diets from 5 to 11 and 6 to 13 d of age in Experiments 1 and 2, respectively. Regression analyses of the data showed that increases in BW and tibia ash were linearly related (P </= 0.01) to percentage dietary P and to quantity of P consumed. Common intercept multiple linear regression was used to derive relative availabilities (RA) with DP assigned a value of 100. On the basis of BW gains, RA of MBM1O and MBM12 ranged from 99.1 to 105.5, depending on the independent variable and the experiment. Similarly, on the basis of tibia ash, RA ranged from 97.3 to 104.8. None of the RA differed (P > 0.05) from 100. Thus, the RA of P from MBM tested were equal to that of P from DP, and particle size of the MBM did not affect RA of P.