Digestibility of phosphorus and calcium in meat, bone meal
One of the problems of using high levels of meat and bone meal in pig and poultry diets is the high variability in the concentration of Ca and P.
Meat and bone meal (MBM) is a by-product of the meat industry providing for a disposal venue to unmarketable animal parts. Apart from its high protein content, MBM contains high levels of calcium (Ca) and phosphorus (P), the latter being the third most expensive nutrient in most diets.
One of the problems of using high levels of MBM in diets for pigs (and poultry), is its high variability in not only in the concentration of Ca and P, but also in their digestibility (or relative bioavailability for poultry), especially of phosphorus.
In a recent study at the University of Illinois, the apparent total tract digestibility (ATTD) of P and Ca and the standardized total tract digestibility (STTD) of P in eight different sources of meat and bone meal (MBM) were determined in pigs, and equations to predict digestibility of Ca and P in MBM were subsequently developed.
On an as-fed basis, the concentration of P in the MBM sources ranged from 2.6 to 5.3 percent with an average of 4.3 ± 0.8 percent whereas Ca concentration ranged from 5.1 to 11.0 percent with an average of 9.2 ± 2.0 percent. In the case of P, the ATTD ranged from 52 to 80 percent (average = 66 percent), whereas the STTD ranged from 55 to 84 percent (average = 69).
In addition, the STTD of P decreased (P < 0.01) as ash, Ca, and P concentration in MBM increased. The STTD of P (percent) in MBM may be predicted as 107.857 - 8.8 × total P [R2 = 0.68, root mean square error (RMSE) = 5.73, P < 0.01].
For more information, see http://www.journalofanimalscience.org/content/91/3/1285.abstract