ADDITION OF RUMINAL ESCAPE METHIONINE AND LYSINE TO MEAT AND BONE MEAL

A growth study was conducted to determine the effects of adding rumina l escape methionine and lysine to meat and bone meal (MBM). A basal di et of 44% sorghum silage, 44% corncobs, and 12% supplement (DM basis) was individually fed to 60 crossbred steers (234 +/- 14 kg). Supplemen ts contained either urea, MBM, MBM plus protected methionine (MBM + M) , or MBM plus protected methionine and lysine. Protein sources were fe d to supply 30, 40, 50, and 60% of the supplemental CP, with urea supp lying the remainder. Protein efficiency, calculated as gain above the urea control vs natural protein intake using the slope ratio technique , was used to evaluate the protein sources. The most efficiently used protein source was MBM + M, which was greater than MBM alone (P < .10) . Meat and bone meal plus protected methionine and lysine had a protei n efficiency similar to MBM + M (P > .30), indicating that lysine was not limiting. True protein digestibility of MBM in the gastrointestina l tract of lambs was determined to be 86.1%. In situ analysis performe d by 12-h ruminal incubation of MBM determined the escape CP to be 53. 0% of CP. Amino acid analysis was conducted to compare supplies to req uirements for live animal gain. The urea control failed to meet the me tabolizable protein requirement. Feeding MBM to provide additional met abolizable protein failed to provide an adequate amount of the essenti al amino acid methionine, which was first-limiting. These data indicat e that protein efficiency of MBM can be enhanced by the addition of ru minal escape methionine.