The effect of storage on the nutritional quality of meat and bone meal

The effect of storage on the nutritional quality of meat and bone meal was investigated. Three meat and bone meal samples were stored for 1, 2, 3, 6 and 9 months, with or without the addition of the antioxidants (butylatedhydroxytoluene and butylatedhydroxyanisole). Gross composition, thiobarbituric acid reactive substances (TBARS), gross amino acid content and the coefficient of the ileal apparent digestibility (CIAD) of amino acids was determined at each time point. The concentration of TBARS increased sharply during the first 2 months of storage thereafter TBARS decreased until 9 months. The addition of antioxidants to the meat and bone meal significantly decreased the TBARS compared to the unsupplemented samples. There was a significant (P<0.05) effect of time on the dry matter, crude protein, crude fat, cysteine, histidine and methionine content. There was no significant (P>0.05) effect of antioxidant addition or the interaction between time and antioxidant addition on the gross content of nutrients. A significant quadratic trend over time was obtained for the dry matter content while no significant linear or quadratic regression was obtained for the other components. There was no significant (P>0.05) effect of time, antioxidant addition or the interaction between time and antioxidant addition on the CIAD of any of the amino acids with the exception of methionine and cysteine for which a significant (P<0.05) effect of time was found. The CIAD of methionine decreased linearly over time while no significant trend was found for cysteine. Storage of meat and bone meal at ambient temperatures, although resulting in oxidation of the fat, does not add to the variation in the CIAD of amino acids normally observed.