PROCESSING OF FEATHER MEAL TO MAXIMIZE ITS NUTRITIONAL-VALUE FOR POULTRY

Feather meals (FM) of different quality were produced in commercial processing equipment. Three different samples were prepared in a continuous hydrolyzer and one in a batch hydrolyzer. The steam pressures used for processing were 207, 310 and 414 kPa in the continuous hydrolyzer and 283 kPa in the batch hydrolyzer. Five roosters were fed 30 g of each FM by crop incubation to measure digestibility. Average amino acid digestion coefficients were 0.72 for the 207 and 3 10 kPa processed FM and 0.66 for the 414 and 283 kPa FM. The weighted sulfur amino acid digestion coefficient was similar when FM was processed at 207 kPa (0.623) and 310 kPa (0.626) but declined when processed at 414 kPa or in batch processing. There was a similar trend for the lysine digestion coefficients. The true metabolizable energy of the FM was (kJ g-1): 207 kPa, 15.04; 310 kPa, 14.19; 414 kPa, 14.89; 283 kPa, 14.24. Pepsin digestible protein (PDP) increased from 0.66 in the 207 kPa FM to 0.81 in the 414 kPa FM, with 0.79 in the 283 kPa PM. Acid detergent soluble nitrogen coefficients were similar to those for PDP, except that the 283 kPa FM had a value of 0.69. These results indicate that FM with a PDP of 0.66 is nutritionally equal to FM with a PDP of 0.77 and that an FM with a PDP of approximately 0.8 is overprocessed.