Effect of formulating diets using differing meat and bone meal energy data on broiler performance and abdominal fat content.

The metabolizable energy (ME) value of meat and bone meal (MBM) appears to be underestimated in the 1984 National Research Council (NRC) table of composition. Two experiments were conducted with broiler chickens from 3 to 7 wk of age to study their response to diets formulated with MBM assigned different ME values. Broiler grower (3 to 6 wk) and withdrawal (6 to 7 wk) diets containing 10% MBM were formulated using ME values of 1,960 (1984 NRC table), 2,250, or 2,500 kcal/kg for this ingredient. Corn-soy grower and withdrawal diets containing no MBM were also fed. No significant differences in body weight (7 wk) were observed in either males or females fed the diets. Feed:gain ratios were not different among males but in one experiment ratios for females fed the MBM diet formulated on the 2,500 kcal/kg ME basis were nonsignificantly higher than ratios for those fed the corn-soy diet. Abdominal fat as a percentage of body weight of males fed the diets containing MBM calculated on the 1,960 or 2,250 but not the 2,500 ME basis was significantly higher than that of males fed the diet without MBM. No significant differences in abdominal fat content were observed in females fed the different diets. The results show that an ME value higher than that given in the NRC table should be used for MBM in practical diets and that females are less sensitive than males to the influence of calorie:protein ratio on abdominal fat deposition.