Estimation of the metabolizable energy content of meat and bone meal for swine1,2

Experiments were conducted to determine apparent ME (AME) and apparent nitrogen-corrected ME (AME(n)) of 21 meat and bone meal (MBM) samples and to develop regression equations for predicting energy value of MBM. One hundred ninety-eight 32-kg of BW barrows were used for the study. The 22 treatments consisted of 1 corn-soybean meal reference diet and 21 test diets in which 21 MBM samples replaced 100 g/kg of corn and soybean meal such that the ratio of corn and soybean meal was the same in the reference and test diets. The DE, AME, and AME(n) of the MBM samples were determined by the difference method in a metabolism study consisting of 5-d adjustment and 5 d of total collection of feces and urine. On a DM basis, GE of MBM ranged from 3,895 to 5,193 kcal/kg, CP ranged from 491 to 641 g/kg, and ash ranged from 142 to 338 g/kg. The AME of the MBM samples ranged from 2,320 to 3,872 kcal/kg, whereas AME(n) ranged from 2,212 to 3,767 kcal/kg. None of the proximate compositions explained >50% of the variation in energy content of the MBM. Fat was positively correlated with GE, DE, AME, and AME(n) (r < or = 0.44), but CP, ash, Ca, and P were negatively correlated with DE, AME, and AME(n). The ratios of the proximate compositions to each other were correlated with the energy contents of the MBM. Crude protein:fat and GE:fat were negatively correlated with DE, AME, and AME(n) of the MBM (r ranged from -0.17 to -0.39), but fat:ash had the greatest positive correlation with AME and AME(n) compared with other ratios tested. When the data from 1 MBM sample that was an outlier were removed from the analysis, R(2) was 0.42 for AME and AME(n). The 4 variables that produced the best prediction equation for AME and AME(n) were GE, CP, P, and ash. The prediction equation for AME using these variables was AME = 13,587 - (1.25 x GE, kcal/kg) - (3.51 x CP, g/kg) + (30.4 x P, g/kg) - (16.4 x Ash, g/kg), and for AME(n), the equation was AME(n) = 13,547 - (1.25 x GE, kcal/kg) - (3.59 x CP, g/kg) + (31.0 x P, g/kg) - (16.5 x Ash, g/kg). It was concluded from this study that MBM is a good energy source for pigs and that, although other extrinsic factors may contribute to the variations in energy content of MBM, proximate compositions should be sufficient to predict the energy value of MBM for pigs.