Author : Patadjai, Andi Besse

Summary : Study on fish silage prepared with Gracilaria sp., with and without abalone viscera was conducted to evaluate the rate of hydrolysis during the ensiling process. The fish-Gracillaria sp.-abalone viscera silage was further subjected to nutritional value test as poultry feed. Three silage were prepared using 5% propionic acid and formic acid (ratio 1:1) to contain : (a) 100% fish by catch (Silage F), (b) 70% fish by catch, 25% Gracilaria sp. and 5% abalone viscera (Silage FGA). These silage were stored for 15 days and stirred daily. Chemical components such as pH, amino nitrogen, polypeptide, and monosaccharide content were determined at regular intervals within the 15-day ensiling period. Isonitrogenous feeds were then formulated to contain fish-Gracillaria sp. abalone viscera silage Feed (II) and fish silage (Feed III). Nutritional value of these diet (i.e. Feed II and Feed III) were compared with that of commercial feed (Feed I) which was used as the control, based on the growth response of chickens. Results showed that rate of decrease in pH value was sufficiently rapid to stabilize the three silage. Silage F showed significantly higher pH value throughout the ensiling period, compared with Silage FG and Silage FGA. No significant difference (P<0.05) was, however, found between Silage FG and Silage FGA. Results can be attributed to incorporation of Gracilaria sp. in silage production, which provided favorable condition to decrease the pH value. Amino nitrogen content of all silage increased with ensiling time. Silage F exhibited the highest amino nitrogen content during 15 days of ensiling, followed by that of Silage FGA. Although the amino nitrogen content of Silage FGA was higher than that of Silage FG, significant differences (P<0.05) were noted only after 12 days of ensiling. Polypeptide content of all silage decreased after 3 days of ensiling. Silage FGA exhibited the highest polypeptide content after 9 days of ensiling.