A biotechnological process for treatment and recycling poultry feathers as a feed ingredient A. Bertsch a , N. Coello b, * a Instituto de Quı ´mica y Tecnologı ´a, Facultad de Agronomı ´a, Maracay, Universidad Central de Venezuela, Venezuela b Laboratorio de Procesos Biotecnolo ´ gicos, Instituto de Biologı ´a Experimental, Caracas, Universidad Central de Venezuela, Venezuela Received 2 September 2004; received in revised form 6 December 2004; accepted 9 December 2004 Available online 13 March 2005 Abstract A strain of Kocuria rosea with keratinolytic capacity was cultured aerobically on submerged feathers to obtain a fermented feather meal (FFM). This FFM enriched with cells of K. rosea mainly contains crude protein (71%). The pepsin digestibility of the fermented product (88%) was similar to the value of the commercial feather meal and more than 70% greater that untreated feathers. The bacterial biomass improved the content of amino acids lysine (3.46%), histidine (0.94%) and methionine (0.69%). Addi- tionally, the amino acid availability tested by in vivo assay was greater than commercial feather meal. The microbial cells also sup- plied carotenoid pigments to FFM (68 ppm). These results suggest that feather meal enriched with K. rosea may be useful in animal feeding as protein and pigment source. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Kocuria rosea; Feathers; Feather meal; Feedstock; Carotenoid pigment 1. Introduction Poultry feather constitutes the most abundant kerat- inous material in nature. Their accumulation results from the poultry processing industry. Thus this waste product carries potent ecological implications, especially with burgeoning global poultry production. Recycling of feathers is a subject of interest among animal nutri- tionists, because of its potential as a cheap and alterna- tive protein feedstuff. However, limitations to feather utilization arise from its poor digestibility and minimal biological value due to the deficiencies of nutritionally essential amino acids, such as methionine, lysine, histi- dine and tryptophan (Moran et al., 1966). This problem can be partly circumvented by steam-treating feathers to denature the keratin. After milling, a friable meal is ob- tained that is 70–80% digestible (Homer and Shaible, 1980). Nevertheless, a more serious problem lies in the amino acid imbalance besides the formation of non- nutritive amino acids, such as lysinoalanine, lanthio- nine, etc (Wang and Parsons, 1997). In spite of its limi- tations, this meal is incorporated into diet on as-fed in chicken poultry (40–50 g/kg), rainbow trout (150 g/kg), shrimp (330 g/kg) and salmon (400 g/kg), but the result- ing diet needs amino acid supplementation, especially feed-grade lysine and others (Cheng et al., 2002; Brand- sen et al., 2001; Bureau et al., 2000). Considering the thermo-energetic cost of conventional processing of feathers against the backdrop of their limited nutritional improvement, investigation into alternative technology with prospects for nutritional enhancement, environ- mental compatibility, bioresources optimisation seems justifiable (Onifade et al., 1998). Both the digestibility and amino acid balance of feather meal might be improved by microbial action. A number of microorganisms, such as Vibrio sp. strain kr2 (Sangali and Brandelli, 2000), Bacillus 0960-8524/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2004.12.026 * Corresponding author. Fax: +58 212 753 58 97. E-mail address: mcoello@reacciun.ve (N. Coello). Bioresource Technology 96 (2005) 1703–1708