Effect of dietary protein source and probiotic inclusion on pattern of excretion of ammonia and orth ophosphate in holding water in Catla catla culture system

Abstract

This study was performed to determine the daily periodicity of ammonia and orthophosphate excretion in the fish Catla catla with different levels of inclusion of probiotics Bacillus coagulans in processed soybean and Duck weed based diets (approx. 40 percent protein). Two experiments were conducted. In experiment 1, a feeding trial of 90 days was conducted: C. catla fingerlings (average. BW 0.30±0.03g) were fed on Soybean supplemented feed with 1000 (diet D1), 2000 (diet D2), 3000 (diet D3) and 5000 (diet D4) CFUg -1 of B. coagulans as probiotic bacterium. In experiment 2, fishes (average BW 1.79± 0.03 g) were fed on artificial diet containing duckweed (@199.5 g Kg -1 ) with no probiotic bacterium (C1), B. coagulans in proportion of 1000(C2), 3000(C3) and 5000 (C4) cells g -1 of duckweed supplemented feed. At the end of 90 days feeding trial, water sample from each aquaria were collected at 2 hour interval to estimate the excretory levels of total ammonia and reactive phosphate. The peak values for ammonia excretion occurred approximately at 6 th and 12 th hour post feeding while orthophosphate production showed an initial high level at 2 hours post feeding and 2 nd peak at 8 hours post feeding. The low excretion of metabolites was found in group of fishes fed on diet supplemented @ 3000 CFU g -1 of probiotic irrespective of the dietary protein source (Soybean and Duck weed) indicating better dietary utilization of nutrients with optimum inclusion of probiotics. However, the values of metabolites were low in fishes fed on duck weed supplemented diets in comparison to soybean supplemented diets. The low values of metabolite excretion also coincided with higher growth performance. These results clearly indicate that protein source, its level of inclusion and dietary addition of probiotics at optimum level play a significant role in the management of excretory levels of ammonia and phosphorous and thus in turn improving growth performance of fish.