DIETARY THIAMINE REQUIREMENT OF FINGERLING CATLA CATLA (HAMILTON) BASED ON GROWTH, FEED CONVERSION, PROTEIN RETENTION, RNA/DNA RATIO, HAEMATOLOGICAL INDICES AND CARCASS COMPOSITION

Indian major carp, Catla catla is the most important freshwater, commercially cultured food fish species. Because of its high nutritional value and taste, it has greater consumer demand. Catla, along with the other Indian major carps, Labeo rohita and Cirrhinus mrigala form the mainstay of fish culture in India. To improve the production process of this species, it is important to provide nutritionally balanced feeds. The main constraint in preparing nutritionally balanced feeds is the lack of information on its essential nutrient requirements.  Thiamine plays a very important role as the coenzyme thiamine pyrophosphate  necessary for several metabolic decarboxylation and transketolation reactions. It is involved in the oxidative decarboxylation of α-keto acids, such as pyruvate to α-ketoglutarate, and in the transketolase reactions in the pentose phosphate pathway that are essential to provide pentose phosphate for  nucleotide synthesis and dihydronicotinamide adenine dinucleotide phosphate for fatty acid synthesis. Although, data on protein and amino acid requirement is available, no information is available on vitamin requirement of C. catla. Hence, the present study was conducted to determine dietary thiamine requirement to formulate thiamine-balanced feeds for fingerling C. catla.

Dietary thiamine requirement of fingerling Catla catla (7.5±6.5cm; 3.5±1.5g) was determined by feeding casein-gelatine based iso-nitrogenous (35g/100g crude protein) and iso-caloric (400 kcal DE/100g) dry diets containing six graded levels of thiamine (0, 0.2, 0.4, 0.8, 1.6 and 3.2 mg/100g) for 8 weeks. Fish were stocked at the rate of 15 fish per trough for each dietary treatment level in 70-L indoor tanks (water volume 55 L) with a continuous water flow-through (1-1.5L/min) system. The diets were hand-fed to triplicate groups of fish to apparent satiation three times a day at 08:00, 12:30 and 17:30 h. Absolute weight gain, feed conversion ratio, protein retention efficiency, carcass composition, RNA/DNA ratio and haematological indices were found to be best in fish fed  diet containing 0.8 mg/ 100g dietary thiamine. On the basis of growth parameters, it is recommended that the inclusion of dietary thiamine at 0.8 mg/100g of the diet is optimum for fingerling C. catla.