Utilization of sorghum distillers dried grains in extruded and steam pelleted shrimp diets

Use of distillers dried grain with solubles from sorghum (sDDGS) was studied with respect to processing and physicochemical quality of shrimp feed, followed by growth trials with Litopenaeus vannamei (Pacific white shrimp). Shrimp diets with 0%, 10%, 20%, 30% and 40% sDDGS inclusion, as a replacement for soybean meal, were produced using extrusion and steam pelleting. Bulk density of extruded feed (0.53-0.58gcm(-3)) was lower than that of pelleted feed (0.61-0.65gcm(-3)), although sDDGS level did not have an impact. Finished diets were 100% sinking, with some exceptions in the case of extruded feed. Pellet durability index (89.4-96.3%) had an increasing trend up to 20% and 30% sDDGS for extruded and pelleted diets respectively. Extruded feed had higher degree of gelatinization than pelleted feed, although proportion of gelatinized starch generally decreased with sDDGS level. Water stability (76.2-91.6%) was higher for extruded feed as compared to pelleted feed, and remained unchanged or decreased with sDDGS level. The extruded and pelleted diets were evaluated in two growth trials with L.vannamei for duration of 9 and 6weeks in 40 and 60 tanks (initial weight 0.36-0.38g; 10 shrimps per tank) respectively. Significant differences were not observed in final mean weight and survival with respect to sDDGS level, indicating that up to 40% of this novel protein source can be used in feed formulations without affecting the performance of L.vannamei. Comparison of extruded feed with pelleted feed for impact on mean weight and feed conversion ratio did not yield conclusive results.