In vitro and in vivo evaluation of the nutritional value of various hydrolyzed feather meals and comparison of their effect on performance and carcass characteristics of broilers

In the current study, the nutritional value of various hydrolyzed feather meals (HFM) was investigated in two separate experiments (an <i>in vitro</i> and an <i>in vivo</i> experiment). The <i>in vitro</i> experiment was based on a completely randomized design with five replications and seven treatments including (1) Raw feather meal (RFM), (2) HFM by autoclave (Au-HFM), (3) Fermented feather meal (FFM) by <i>Bacillus licheniformis</i> (Bl-FFM), (4) FFM by <i>Bacillus subtilis</i> (Bs-FFM), (5) FFM by <i>Aspergillus niger</i> (An-FFM), (6) FFM by <i>Bacillus licheniformis</i> + <i>Bacillus subtilis</i> + <i>Aspergillus niger</i> (Co-FFM), and (7) HFM by an enzyme (En-HFM). The highest <i>in vitro</i> pepsin-pancreatin and apparent ileal CP digestibility were observed in Co-FFM, and the lowest amount belonged to RFM (P < 0.05). For the <i>in-vivo</i> experiment, 480 1-d-old male Ross 308 broilers were distributed in the experimental units in a completely randomized design with 8 treatments and 5 replicates (12 chicks/replicate). The treatments were: (1) Control diet (without feather meal (FM)), (2), (3), (4), (5), (6), (7), and (8), diets containing 4 % RFM, Au-HFM, Bl-FFM, Bs-FFM, An-FFM, Co-FFM, and En-HFM, respectively. For the <i>in-vivo</i> study, the birds fed control and Co-FFM diets had the highest feed intake, body weight gain, and the lowest feed conversion ratio compared to the other treatments (P < 0.05). The broilers fed the control and FFMs diets had the lowest relative weight of abdominal fat and liver compared to the other groups (P < 0.05). Therefore, our findings advise the poultry feed industry to look for Co-FFM as an effective alternative and cheaper feed ingredient to replace part of soybean meal in poultry diet.