Effect of Extrusion Temperature on Quality of Carp Floating Feed Prepared from Local Feed Resources

Abstract

A fish feed for rohu (Labeo rohita) was formulated from locally available feed ingredients and processed using four different extrusion temperatures i.e., 110, 130, 150 and 170°C maintaining constant moisture and pressure. The extruded feeds so produced were evaluated for physical and chemical characteristics to ascertain their quality. A digestibility study was conducted during a 60d feeding trial to determine the intake and digestibility of nutrients. Intestinal enzyme activity of rohu was also assessed. Results indicated that processing the feed at 130 and 150°C resulted in 100% floating whereas higher or lower extrusion temperatures reduced the floating percentage. As temperature of extrusion increased, the water holding capacity of feed was increased, but lower and higher temperatures of 130 or 150°C, increased the apparent density of feed. The nutrient composition of the four feeds in terms of DM, EE, CF, NFE and total ash were not affected except for the CP which was reduced (P<0.05) while extruded at 170°C. The digestibility of nutrients was not affected by the extrusion temperature of the feeds. The feed intake was significantly higher (P<0.05) with the feed produced at 130 or 150°C extrusion temperature as compared to the feed produced at 110 and 170°C. The amylase and lipase activity of intestine did not show any significant changes after feeding the feeds produced at four different extrusion temperatures. The results indicates that the quality of floating feed for rohu can be maintained optimally by extruding it at temperature between 130 to 150°C.