Morris et al., 1973. Poult. Sci., 52 (3): 1075-1084

Net protein values and nitrogen retention were determined to evaluate feathers processed under different conditions. In addition, each feather meal sample was chemically analyzed for pepsin digestibility, available lysine, ether extract, ash, amino acids and protein content. The “standard” processed feather meal resulted in a lower net protein value than did any of the “new” further-processed feather meals. Feather meal processed for 50 p.s.i. with intermittent agitation (agitate 1 minute, stop 2 minute) resulted in the highest net protein value of all the feather meals. This same feather meal also contained the highest level of available lysine, methionine and histidine when compared with other feather meals. Nitrogen retention decreased linearly when feather meal protein was increased in the diet from 3 to 9%. Only with the 9% feather meal protein level, however, was a marked decrease in nitrogen retention observed.

Feather meals did not differ greatly enough in pepsin digestibility to result in valid conclusions on this basis. Feather meals processed under more severe conditions, however, tended to have slightly higher pepsin digestibility values. Of the lysine present in the feather meals, on the average, 72.5% was “available lysine.” The more severely processed feather meals contained more available lysine than did the feather meals processed under milder conditions.