Higher water temperature enhances dietary carbohydrate utilization and growth performance in Labeo rohita (Hamilton) fingerlings

A 60-day experiment was conducted to delineate the effect of three dietary levels of gelatinized carbohydrate (GC) on growth, nutrient-utilization and body composition of Labeo rohita fingerlings (avg. wt 6.5 +/- 0.3 g) reared at two water temperatures (ambient-AT (26 +/- 0.8 degrees C) and 32 degrees C). Two hundred and sixteen fingerlings were randomly distributed into six treatments in triplicates. Three semi-purified isonitrogenous diets were prepared with graded levels of GC viz. D(1): 40%, D(2): 50% and D(3): 58%. Growth rate, feed efficiency and protein efficiency ratio were significantly (p < 0.05) higher in 50% GC and 32 degrees C reared groups than their AT counterparts. Hepato Somatic Index was higher in AT reared groups compared to 32 degrees C reared counterparts. Apparent digestibility co-efficient of carbohydrate was significantly (p < 0.05) higher at 32 degrees C reared groups but decreased with increasing carbohydrate (GC) levels. Fish reared at 32 degrees C showed significantly (p < 0.05) higher amylase, protease and hexokinase activities while glucose-6-phosphate dehydrogenase and glucose-6-phosphatse were significantly (p < 0.05) higher at ambient temperatures. The results obtained in present study indicated that L. rohita could utilize higher level (50%) of dietary carbohydrate at 32 degrees C.