Evaluation of rubber seeds (Hevea brasilliensis) fermented meal using rumen liquour as a protein source in diet of nile tilapia (Oreochromis niloticus).

Abstract

This research is aimed to investigate the effect of replacing soybean meal with rubber seed meal (RSM) as protein sources for feed of Nile tilapia (Orecochromis niloticus) strain Nirwana. The fish (8.14 ± 0.08 g) were cultured in rearing aquaria (100x50x50 cm3) connected to a recirculating aquaculture system, and fed three times daily with 5 different concentrations of RSM feeds: A (0% RSM), B (25% RSM), C (50% RSM), D (75% RSM) and E (100% RSM), with the same protein content and gross energy: 31% and 433.5 kcal GE g-1 respectively. The study consisted of two phase. Phase one aims to determine the digestibility of feed (14 days) and phase two study aimed to growth performance (50 days). During the feeding period, some parameters were measured including feeding rate, feed efficiency, protein retention, fat retention, daily growth rate, cholesterol, triglycerides, feed digestibility, LDL (low density lipoprotein), HDL (high density lipoprotein), hepatosomatic indeks (HSI), glycogen in heart and muscle, and lipid in hearth and muscle. Experimental design was set according to completely randomized design with 5 treatments and 4 repetitions of each. Data were statiscally analysed with one-way analysis of variance (ANOVA) using software Minitab version 16.0, with 95% (p<0.05) confidence interval. The results showed that the replacement of soybean meal with the rubber seed meal at 50% gave the highest protein digestibility (92.95%) and total feed digestibility (70.30%). On the contrary, increasing rate of the replacement up to 100% decreased both protein digestibility and total feed digestibility to 86.79% and 54.58%. Substitution up to 75% and 100% showed low blood protein to 3.57% and 2.58%. Other results revealed that the use of 75% and 100% lead to the increasing of cholesterol, triglyceride and LDL (low density lipoprotein), but decreased HDL (high density lipoprotein). Overall, the replacement of soybean meal with fermented rubber seed meal as protein sources showed no significant different in fish growth rate; 3.43% (25% RSM), 3.42% (50% RSM) and 3.41% (control). This research result may suggest that rubber seed meal which was previously fermented with rumen liquid can be used to replace soybean meal as protein sources and can be used up to 50% in diet of nile tilapia.