Recycling dead hens by enzyme or sodium hydroxide pretreatment and fermentation

This study was conducted to evaluate the recycling of whole dead hens into feed ingredients by enzyme or sodium hydroxide pretreatment and fermentatio n. Evaluation criteria included nutrient preservation, pathogenic microorga nism elimination, and assays of nutritional quality. The pH levels of enzym e- and NaOH-treated hen carcasses decreased from 6.01 and 7.66 to 4.18 and 4.24, respectively, during the 21-d fermentation. Hydrogen sulfide levels w ere not detected on Days 1 and 3 from the enzyme treatment; however, high l evels (800 ppm) were measured from the NaOH treatments. By Day 21, H2S leve ls of both treatments had decreased to 78 ppm. The control, enzyme, and NaO H treatments before fermentation contained high levels of Escherichia coli and Staphylococcus aureus; however, after fermentation, these potential pat hogens were eliminated in the enzyme and NaOH treatments. Levels of CP EE, and ash of the control product were higher than either the enzyme or NaOH t reatment. NaOH reduced pepsin digestibility by 11% compared to the enzyme t reatment. In a bioassay, the chicks fed control autoclaved hen meal (CHM) h ad higher (P < 0.05) feed intake, weight gain, protein efficiency ratio (PE R), and net protein ratio (NPR) than enzyme-treated, fermented, and autocla ved hen meal (EHM) or NaOH-treated, fermented, and autoclaved hen meal (NHM ). However, the AME(n) of the CHM and EHM were higher than the NHM (P < 0.0 5) when evaluated using mature cockerels, These results indicated that ferm entation processing of dead hens reduced the concentration of some nutrient s and depressed growth performance when hen meals were fed to young chicks.