Batch dry rendering: Influence of processing conditions on meat meal quality

Abstract

Abstract A series of meat‐and‐bone meal samples was prepared during batch cycles in a commercial dry‐rendering plant, in which offal was cooked to the usual end‐point, then the cooker contents were held at high temperatures for prolonged periods. The expected decrease in nutritive value was not detected by chick assays even for meals that had been heated at 145 ºC for 2 h after end‐point. An apparent increase in nutritive value was detected in meals heated at 115 ºC for up to 80 min after end‐point. Since chick assays were carried out using diets similar to industrial formulations, it is concluded that the experimental processing conditions had no detrimental effect on the meals as feed additives. Available lysine values showed no trends with processing conditions and tended to confirm that the biological value of the meal protein had not suffered. Results of chemical analyses showed some variability, attributable mainly to sampling errors that are hard to avoid when obtaining a small sample representative of the 5 to 10‐kg portions of meal used in chick assays.