15 MARCH 1999
GROWTH RESPONSE OF YOUNG CATFISH HETEROPNEUSTES FOSSILIS (BLOCH) FED VARYING LEVELS OF DIETARY CARBOHYDRATE
Erfanullah, A.K. Jafri-1998
Journal of Aquaculture in the Tropics, 13(2): 107-118
Abstract:
Effect of varying levels of dietary carbohydrate have been examined on the growth, conversion efficiencies, body composition, and nutrient retention efficiency of young catfish Heteropneustes fossilis (8.15 +/- 0.23, g, s.e.). Iso-nitrogenous (40% CP) experimental diets, containing graded levels of carbohydrate (0, 5, 10, 15, 20, 25, or 30%), with variable gross (3.35-4.50 kcal/g protein as AE), were fed to triplicate groups of ten fish each in 70 l high density polyvinyl flow-through (1-1.5 l/min) type indoor circular troughs (water volume 55 l). Fish were fed to apparent satiation, six days a week, twice daily at 0800 and 1600 hours. Over the six week growth trial, maximum growth, conversion efficiencies, and increased nutrient retention were seen in fish at 20% dietary carbohydrate and 3.23 kcal/g AE diet, corresponding to an energy to protein ratio of 8.08 kcal/g protein. Changes in the whole body composition were significantly (P<0.05) affected by the levels of carbohydrate intake. Increase in dietary carbohydrate intake resulted in higher values for dry matter, fat, and body energy contents. Crude protein and ash remained unaffected (P>0.05) with increase in dietary carbohydrate levels. Protein and energy retention efficiencies increased linearly up to 20% carbohydrate inclusion in the diet, beyond which a significant fall (P<0.05) in the values appeared. A four-fold increase in liver and gut weights, and a two-fold increase in hepato-and gastro-somatic indices were observed in fish fed 30% dietary carbohydrate.
(Fish nutrition Research Laboratory, Department of Zoology, Aligarh Muslim Universiy, Aligarh 202 002, India)