Evaluation of raw and hydrothermically processed leguminous seeds as supplementary feed for the growth of two Indian major carp species

摘要

To study the effect of four different raw and hydrothermically processed leguminous seeds, namely Glycine max (soybean), Vigna radiata (moong), Vigna ungiculata (cowpea) and Cyamopsis tetragonaloba (guar) on growth in the fingerlings of Cirrhinus mrigala (mrigal) and Labeo rohita (rohu), two experiments were conducted. The first experiment was conducted under laboratory conditions (LD 12:12 at 25 degreesC) and the mrigal fingerlings were fed @2% BW d(-1) for 30 days. Before using the seeds as feeds, they were hydrothermically processed (15 lbs at 121 degreesC for 15 min) for the elimination of antinutrient factors (ANF). The results indicate that 15 minute autoclaving significantly reduces the trypsin inhibitor activity. Phytase-phosphorous and tannins were also analysed from raw and treated beans. Studies on mrigal have revealed that weight gain was significantly low (P<0.05) in the fish fed on raw beans compared with the fingerlings fed on processed bean proteins. Among the various raw diets used, significantly highest growth (P<0.05) was observed in fish fingerlings fed on raw moong, followed by raw soybean, cowpea and guar. On the other hand, when beans were processed, the highest growth was observed in fingerlings fed on processed soybean. Studies have further revealed that hydrothermal processing also affected the values of the feed conversion ratio, gross conversion efficiency, protein efficiency ratio, gross protein retention, gross energy retention and ammonia excretion. Proximate composition of the carcass revealed high accumulation of protein, fat and energy in fingerlings fed on processed soybean in comparison with other diets. Keeping in view the higher weight gain in fish fed on hydrothermically processed bean proteins, only processed bean diets were fed to the fingerlings of mrigal and rohu stocked in fish ponds (experiment 2). A significant (P<0.05) increase in mean fish weight, and specific growth rate was observed in fingerlings fed on hydrothermically processed soybean, followed by moong and cowpea. Weight gain for mrigal fingerlings remained significantly low in comparison to the rohu fingerlings fed on similar diets. An investigation on the effects of feeds on water quality parameters indicate that the trophic status of the ponds where soybean was used as fish feed remained high in comparison to the other treatments. A significant positive correlation of nutrients, NPP and plankton population with fish growth was also observed.