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Meat and bone meal (MBM) is a product of the rendering industry composed primarily of the offal and bones of slaughtered livestock, fat from unmarketable animal tissues, unsellable retail meat products, and whole condemned carcasses, excluding animal hair, blood, hooves, horns, and contents of the gastrointestinal tract. MBM contains greater concentrations of Ca and P than all plant feed ingredients and it can replace inorganic phosphates in swine diets without negatively affecting bone integrity and growth performance. However, high variability has been reported for the concentration of P and Ca and for the relative bioavailability of P among sources of MBM. Use of P in feed ingredients may be expressed as standardized total tract digestibility (STTD) of P, which is calculated by correcting values for the apparent total tract digestibility (ATTD) of P for basal endogenous P losses.
The objectives of this experiment were 1) to determine the ATTD and STTD of P and the ATTD of Ca in 8 different sources of MBM, 2) to estimate variation among MBM sources, and 3) to develop equations to predict the concentrations of digestible P and Ca in MBM. A total of 72 growing pigs with 18.0 ± 1.6 kg of body weight (BW) were individually housed in metabolism cages and were randomly allotted to 9 diets with 8 replicate pigs per diet. Eight diets were formulated with 8% of each source of MBM, and MBM was the sole source of P and Ca in each diet. A P-free diet was used to measure basal endogenous P losses (EPL) by the pigs.
The ATTD of P and Ca differed (P < 0.05) among MBM sources. The STTD of P was different (P < 0.05) among MBM sources. The ATTD of Ca and the STTD of P decreased (P < 0.01) as ash, Ca, and P concentration in MBM increased, and the ATTD of Ca was positively related (R2 = 0.99, P < 0.001) with the STTD of P. The STTD of P (%) 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] whereas ATTD of Ca (%) may be predicted as 105.375 – 9.327 × total P (R2 = 0.75, RMSE = 4.70, P < 0.01).
The concentrations and the digestibility values for P and Ca varied among sources of MBM. However, prediction equations using the concentrations of total P in MBM may be used to estimate P and Ca digestibility in MBM fed to growing pigs. There is a strong positive correlation between the concentrations of ash and Ca and P in MBM. Likewise, there is a strong positive correlation between the ATTD of Ca and the STTD of P, but there is a negative correlation between the digestibility of Ca and P and the concentration of Ca and P in MBM.
Sulabo, R. C. and Stein, H. H. (2013). Digestibility of phosphorus and calcium in meat and bone meal fed to growing pigs. J. Anim. Sci. 2013.91:1285–1294. doi:10.2527/jas2011-4632