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To optimize production in growing calves, escape protein is often supplemented to meet the animal's metabolizable protein requirement. Meat and bone meal (MBM) is a rendered animal byproduct often used as a source of escape protein. However, previous studies have shown a lower protein efficiency for MBM relative to blood meal. This has been attributed to the escape protein and/or amino acid composition of MBM being inadequate to the specific needs of the growing calf. Collagen, which can comprise a fraction of MBM protein, contains negligible amounts of the essential amino acids methionine and tryptophan.
Recent research has identified methionine as the first limiting amino acid in MBM. Efficiency of protein utilization was greater in steers consuming MBM plus rumen protected methionine than for MBM alone. Rumen protected methionine and lysine did not improve protein efficiency over methionine alone, suggesting MBM contained adequate lysine.
Two methods for increasing the flow of methionine to the small intestine are supplementation with a rumen protected form of methionine. or increasing the amount of methionine from MBM that escapes ruminal degradation. While non-enzymatic browning of soybean meal with sulfite liquor has been successful in increasing the escape protein value from 30% to 75%. the value of this procedure in increasing the escape protein of MBM remains undetermined.