Effects of dietary P:E ratio and Rhizoclonium in two stocking densities on growth and profitability of Nile tilapia in intensive pond culture

Yashier U. Jumah, Barry L.M. Tumbokon, Augusto E. Serrano Jr
2020 Israeli Journal of Aquaculture (Bamidgeh)  
The present study aimed to determine whether or not combining Quillaja saponin (QS) and k-carrageenan (KC) as feed supplements could have additive or synergistic effect as growth-promoters and/or immune enhancers against hyposalinity stress in Penaeus monodon post larvae. Three separate experiments were done: (a) a random three days attractability test; (b) a 30-day feeding trial to determine optimal inclusion of combined QS+KC; and (3) a 24 h acute hyposalinity stress test following 30-day
more » ... ollowing 30-day feeding five experimental diets. Attractability results showed that the QS+KC very briefly attracted the shrimps for 2 min (p<0.05) but became non-significant after longer periods. In the feeding trial, 5 experimental diets containing graded levels of QS+KC (1:1), namely, 0.0, 0.2, 0.4, 0.6, and 0.8 g kg -1 were fed to groups of shrimps. Results showed that the final average body weight (FABW), weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR) values of shrimps in the supplemented groups were significantly better than those of the control group; the values of those in 0.2 and 0.8 g×kg -1 QS+KC groups were not significantly different from those of the control group. Feed intake (FI) and protein efficiency ratio (PER) values were not affected by the supplementation (p>0.05). Optimal inclusion level of dietary QS+KC was determined to be 0.4 g×kg -1 . After the feeding trial, shrimps were transferred from 24 ppt salinity media to 2 ppt. All QS+KC-fed groups exhibited significantly lower cumulative mortality rate than that of the 0.0 QS+KC group (p<0.05). The determined level of QS+KC that elicited the lowest cumulative mortality rate was 0.5 g×kg -1 . In conclusion, the study demonstrated that the combined dietary Quillaja saponin and kappa carrageenan acted synergistically in the promotion of growth and feed efficiency and in the enhancement of immune response against acute hyposalinity stress.
doi:10.46989/001c.21688 fatcat:vyl37tdocncptelznh2fgeg334