Laboratory and field investigations on the effect of scheduled meal timings on growth performance and nutrient retention in an Indian major carp,Cirrhinus mrigala (Ham) fingerlings: Effect on nitrogen retention and excretion of metabolites

To investigate the effect of scheduled meal timings on growth performance in Cirrhinus mrigala fingerlings, two experiments were conducted. The first experiment was conducted under laboratory conditions and the fish were submitted to schedule meal timings (at 08:00, 12:00,16:00, 20:00, 00:00 and 04:00). A control on continuous feeding was also maintained. ANOVA had revealed a significant (p < .05) increase in live weight gain (g), growth per cent gain in body weight, specific growth rate, PER, GPR, GER and APD (%) values in fingerlings fed between 12:00 and 16:00 hours. A decline in growth parameters, nutrient retention and an increase in FCR values were observed in the group fed at 20:00, 00:00 hours and also in the control group. Studies have further revealed that meal timings had also significantly (p < .005) affected protein digestibility, nitrogen retention and excretion of metabolites . Fish carcass composition had significantly (p < .05) higher accumulation of protein (14.82 ± 0.032), fat (5.51 ± 0.006) and energy (5.95 ± 0.004) in the group fed at 16:00 hours. The second experiment was conducted under field conditions and the fish were submitted to schedule meal timings (at 08:00, 12:00, 16:00 and 20:00). A control on continuous feeding was also maintained. Significantly (p < .05) higher values in growth parameters were observed in the group fed at 16:00 hours and lower values in the group fed at 20:00 hours and also in controls. Water quality, nutrients and productivity status of ponds revealed favourable levels and appears to have been affected by meal timings. Thus, in C. mrigala, timings of food intake can serve to optimize the utilization of ingested calories.