Dietary inclusion effects of cabbage by-product, chicken by-product, and citrus peel by-product on growth performance of abalone (Haliotis spp.)

Abstract

1. Dietary effect of substituting Saccharina japonica with cabbage extract by-product on the growth, body composition and air exposure of juvenile abalone (Haliotis discus hannai Ino 1952) This study aims to assess the effect of replacing various levels of Saccharina japonica with cabbage extract by-product (CEB) in juvenile abalone (Haliotis discus hannai) feed. The 1260 abalone were averagely and randomly distributed into 18 net cages. Five formulated diets were prepared. Five diets were formulated to contain 0 (CEB0), 25 (CEB25), 50 (CEB 50), 75 (CEB75), and 100% (CEB100) CEB in replacement to 20% S. japonica. Eventually, dry S. japonica was prepared to make a comparison with five formulated diets on growth performance of abalone. Each diet was fed to triplicate groups of abalone every other day for 16 weeks. After the 16-week feeding trial, thirty abalone from each cage were exposed to air for 24 h, and survival was monitored for 7 days. Weight gain and specific growth rate (SGR) of abalone fed all formulated diets were superior to abalone fed the S. japonica. Weight gain and SGR of abalone linearly enhanced with increased replacement levels of S. japonica with CEB. The chemical composition of the soft body of abalone showed no significant difference among experimental diets. Survival of abalone fed all formulated diets was superior than abalone fed S. japonica after the 24-h air exposure. In conclusion, CEB could be completely (100%) substituted for S. japonica in abalone feeds when 20% S. japonica was incorporated. Replacement of S. japonica with CEB in abalone feeds could increase growth rate of abalone, but lower feed cost. 2. Chicken by-product meal as replacement to fish meal in juvenile abalone (Haliotis discus hannai Ino 1952) feed The study aims to assess the effect of replacing various levels of fish meal with chicken by-product meal (CBM) in juvenile abalone (Haliotis discus hannai) feed. Five diets were formulated to contain 0 (CBM0), 25 (CBM25), 50 (CBM 50), 75 (CBM75), and 100% (CBM100) CBM in replacement to 24% FM. Dried Saccharina japonica, which is the natural for this species of abalone was also prepared. Each diet was fed to triplicate groups of abalone. A total of 1,260 abalone assigned into eighteen cages were fed for 16 weeks. After the 16-week feeding trial, thirty abalone from each cage were exposed to air for 24 h, and survival was monitored for 7 days. Results showed that weight gain and specific growth rate (SGR) of abalone fed the CBM0 (1.82 ± 0.12% and 0.93 ± 0.040%/day, respectively) diet were significantly (p < 0.02 for both) higher than those of abalone fed the CBM100 (1.36 ± 0.06% and 0.78 ± 0.024%/day, respectively) diet. The chemical composition of abalone soft body exhibited no difference (p > 0.05) among all experimental diets. Survival of abalone during the 7-day post observation period after the 24-h air exposure exhibited no remarkable (p > 0.8 for Log Rank and Wilcoxon tests) difference among all formulated diets according to analysis of Kaplan-Meier survival curve. In conclusion, CBM can replace FM up to 75% in abalone diet without any adverse effects on growth performance and survival. 3. Dietary inclusion effect of citrus peel by-product as an additive on the growth performance, body composition, and various stress resistance of juvenile abalone (Haliotis discus) compared to ethoxyquin Dietary effect of supplementation with citrus peel by-product (CPB) as an additive on the growth, body composition, and different stress resistance of juvenile abalone (Haliotis discus) was determined, and compared to ethoxyquin. The juvenile abalone randomly assigned into 24 net cages (120 abalone per cage) were daily fed to satiation for 16 weeks.. Seven formulated diets with supplementation of 0, 0.5, 1, 2, 3, and 5% CPB and 0.001% ethoxyquin were formulated, and referred to as the CPB0, CPB0.5, CPB1, CPB2, CPB3, CPB5, and EQ diets, respectively. The dry Saccharina japonica was also prepared in order to make comparison with the formulated diets on growth of abalone. Each diet was assigned to triplicate groups of abalone. After the 16-week feeding trial, 60 abalone chosen from each cage were subjected to the 20-h air, 12-h low salinity at 25 psu, and 20-h high temperature at 30℃ exposure stressors, respectively, and then survival was monitored. Abalone fed all formulated diets produced superior weight gain, specific growth rate (SGR), shell growth to abalone fed the S. japonica. The diet with supplementation of CPB linearly enhanced weight gain of abalone. However, abalone fed all experimental diets showed no difference on the chemical composition of the soft body. Diets with supplementation of CPB or EQ improved survival of abalone when subjected to the 20-h air and high temperature exposures. In conclusion, CPB was a very effective additive as growth enhancer as well as stress reducer in abalone diet. The greatest weight gain, SGR, and stress resistance subjected to the 20-h air and high temperature exposures were obtained in abalone fed the CPB5 diet.