RESUMO
BACKGROUND AND OBJECTIVE: Feather wastes are the most abundant keratinous material in the nature and its accumulation causes multiple environmental problems. Nutritive value upgrading of such wastes through biological treatments may provide ruminant's rations with high quality and cost effective source of protein. Therefore, the main objective of this study was to investigate the potential uses of biologically treated feathers (BTF) as a feedstuff for ruminants through in vitro experiments. MATERIALS AND METHODS: Keratinase production time course was performed by ten microbial isolates (3 fungal, 3 actinomyces and 4 bacterial isolates) under static and shaking conditions using turkey feather- synthetic medium. The chemical composition and amino acid analysis for the crude feathers, BTF and soybean meal were determined according to AOAC methods. Two in vitro experiments were conducted to study the effects of crude feathers, BTF and modified ruminant rations (in which soybean meal were substituted by the BTF in 10, 20 and 30%) on rumen fermentation characteristics. Ration's Dry Matter (DM), Organic Matter (OM), Neutral detergent fibre (NDF) and Acid detergent Fibre (ADF) degradability by rumen microorganisms were tested using batch culture technique. Ruminal final pH, ammonia-nitrogen, total volatile fatty acids and short chain fatty acids concentrations were determined after 24 h of incubation. The total gas production volume was determined using 100 mL glass syringes. RESULTS: Bacillus licheniformis ALW1 was the most potent keratinase producer strain under static condition at 37°C for four days of incubation. Feather biological treatment by Bacillus licheniformis increased its content of some of essential-sulphur amino acids. The degradability of BTF by rumen microorganisms was 4 folds higher than crude feather degradability. There were no significant differences between control and partially substituted (R10 and R20) rations in all of rumen fermentation characteristics. CONCLUSION: The utilization of BTF as substitute for costly soybean meal in ruminant's rations up to 20% had no negative effect on all rumen fermentation characteristics.
