Increasing nutrient availability of feather meal for ruminants and non-ruminants using an ammonia pressurisation/depressurisation process

Abstract

An ammonia pressurisation/depressurisation process (PDA) was evaluated for efficacy in enhancing solubility and digestibility of feather meal (FM) protein. Commercial FM was processed for 5 min with variable ammonia loadings (0.5–2 g g−1 DM), moisture contents (10–50%) and temperatures (75–90 °C). Dry matter and protein solubility were determined in a 0.15 M NaCl solution (6 h, 39 °C) and soluble protein content was determined by the Lowry method. Ruminal solubility was determined by the Kjeldahl method as protein lost in the rumen (1 min) of a cannulated steer. Protein digestibility (crude protein by Kjeldahl analysis) was determined using the in situ dacron bag and pepsin techniques. Protein solubility in the untreated FM was low (13.3 and 7.2%, in NaCl and in rumen fluid, respectively) and increased (p < 0.05) to 39.4 and 23.0%, respectively, in the treated FM at the optimal conditions (50% moisture, 2 g ammonia g−1 dry FM and 90 °C). Ruminal and pepsin protein digestibilities increased (p < 0.05) with increasing moisture content, ammonia loading and temperature. Protein digested in the rumen at 12 h increased from 21.9 (untreated) to 43.0%. Highest digestibility value at 48 h was 54.8%. Pepsin protein digestibility increased (p < 0.05) from 35.4% in the untreated FM to 89.3% in the optimal treatment. Protein solubility in NaCl correlated very well (0.98) with pepsin digestibility. The 3‐fold increase in solubility and 2‐fold increase in digestibility could improve nutrient availability of FM and increase its value as a protein source for both ruminants and non‐ruminants. © 1999 Society of Chemical Industry

In vitro pepsin digestibility and amino acid composition in soluble and residual fractions of hydrolyzed chicken feathers

“…Increased IVPD with prolonged autoclaving time is in accordance with Steiner et al ( 1983 ). The feather keratin solubilizing effect of NaOH in experiments 1 and 2 is in accordance with Mukesh Kumar et al ( 2012 ) and studies using other alkaline solutions (Ferrer et al, 1999 ; Coward-Kelly et al, 2006 ; Mokrejs et al, 2011 ). Both alkali Na 2 SO 3 and heat treatments are known to cleave disulfide bonds (Florence, 1980 ; Thannhauser et al, 1984 ; Chojnacka et al, 2011 ).…”

“…Chemical hydrolysis has been studied with sodium hydroxide (NaOH), potassium hydroxide (KOH) (Mokrejs et al, 2011 ), or calcium hydroxide (Ca(OH) 2 ) (Coward-Kelly et al, 2006 ), sodium sulfite (Na 2 SO 3 ), and phosphoric acid (H 3 PO 4 ) (Steiner et al, 1983 ). Furthermore, enzymatic hydrolysis with commercial proteases or supernatants of keratinolytic microorganisms (Tiwary and Gupta, 2012 ), microbial fermentation (Elmayergi and Smith, 1971 ), and physical extractions, by steam-flash explosion (Zhang et al, 2014 ) or other processes where the pressure decreases suddenly (Ferrer et al, 1999 ) have been tested. In most research aiming to increase the digestibility of chicken feathers, the focus has been on utilizing hydrolyzed feathers without separating solubilized and residual fractions (Steiner et al, 1983 ; Papadopoulos et al, 1986 ; Moritz and Latshaw, 2001 ; Grazziotin et al, 2006 ; Mukesh Kumar et al, 2012 ; Zhang et al, 2014 ).…”