Metabolizable energy of meat and bone meal from Spanish rendering plants as influenced by level of substitution and method of determination.

Experiments were conducted to determine the MEn of eight meat and bone meal (MBM) samples. Samples averaged (DM basis): 6.01% moisture, 4.25 kcal gross energy (GE)/g, 53.3% CP, 14.5% ether extract (EE), 29.6% ash, 9.2% calcium, and 4.3% phosphorus. Samples of MBM were substituted in a corn basal diet at levels of 6, 12, 18, and 24%. Values of AMEn were determined at each level of substitution and with regression analysis, because, in general, there were no significant deviations from linearity between dietary AMEn and inclusion level. When considering all the samples studied, the average AMEn values determined with substitution at the 6, 12, 18, and 24% levels of inclusion were 2.91, 2.76, 2.67, and 2.75 kcal/g, respectively, the differences not reaching significance (P greater than .05). The TMEn values were determined by Sibbald's fasted cockerel method. Average values of MBM ME were similar whether determined by calculations based on substitution in the diet or by regression of the data (2.75 and 2.69 kcal/g, respectively). These values were similar to TMEn obtained using Sibbald's method (2.74 kcal/g). Most of the differences in MEn among the samples studied could be attributed to differences in GE, although the percentage of GE metabolized [(ME divided by GE) x 100] tended to increase (R2 = .45; P = .069) when EE content in MBM increased.(ABSTRACT TRUNCATED AT 250 WORDS)