摘要: Two separate experiments were carried out in this study.Experiment 1 studied the effect of dietary Aloe vera on sex ratio of GIFT-tilapia (Oreochromis niloticus) fry.Five groups were designed including a control (basal diet) and 1... 展开 Two separate experiments were carried out in this study.Experiment 1 studied the effect of dietary Aloe vera on sex ratio of GIFT-tilapia (Oreochromis niloticus) fry.Five groups were designed including a control (basal diet) and 100％ Aloe powder included in fish feed at 0.5, 1, 2, and 4％/kg feed, which was administered for 30 days.Fish fed 2.0％ and 4.0％ dietary aloe significantly deviated from the expected 1∶1, male: female sex ratio, in favor of males (X2 =10.08, P＜0.05; X2 =26.08, P＜0.05), respectively, with 4％ presenting the highest percentage of males (67.62％).Contrariwise, survival percentage in fish fed 4％ aloe diet was observed to be significantly lower (P＜0.05) among groups.Furthermore, experiment 2 used the same research design as in experiment 1 to investigate the effect of dietary Aloe on growth performance, physiological responses, and disease resistance against Streptococcus iniae in GIFT-tilapia juveniles, after 60 days administration.Fish fed 0.5％, 1％, and 2％ A.vera supplemented diet significantly improved (P＜0.05) weight gain, absolute growth rate, and specific growth rate.Based on the second order polynomial analysis relation on WG or SGR, the optimum dietary aloe inclusion level suitable for growth was estimated to be 1.96％/kg feed.Moreover, feed intake significantly increased in fish fed with Aloe diet at 1％ and 2％/kg feed.Feed efficiency ratio, feed conversion ratio, and hepatosomatic index was significantly enhanced in 4％ aloe supplemented fish over unsupplemented ones (P＜0.05).Furthermore, dietary aloe significantly influenced concentration of the digestive enzymes and muscle composition of GIFT-tilapia juveniles, and based on the second-order polynomial regression analysis, dietary aloe inclusion level less than or equal to 1.76,1.82, 2.10％/kg feed were determined suitable for amylase, trypsin, and lipase secretion in GIFT-tilapia, respectively.Several haemato-biochemical indices were examined before and after fish were challenged with S.iniae pathogen containing 7.7x106 CFU cells mL-1.Aloe supplemented fish showed a significant increase (P＜0.05) in red blood cells (RBC),haematocrits (Ht), hemoglobin (Hb), white blood cells (WBC), neutrophils, monocytes,eosinophils, serum total protein, glucose, cortisol, complement (C3 and C4), after challenge when compared to unsupplemented ones.Meanwhile, 4％ Aloe supplemented fish showed a decrease (P＜0.05) in RBC, Hb, Ht, WBC, and mean corpuscular hemoglobin (MCH) after challenge compared to unsupplemented ones and other supplemented ones.In addition, lower mean corpuscular volume values (MCV) (P＜0.05) were observed in fish fed with aloe diet at 2％ and 4％ aloe/kg feed than those fed unsupplemented diet.Unchallenged fish fed 0.5％, 1％, and 2％ aloe showed significantly higher values (P＜0.05) of mean corpuscular hemoglobin concentration (MCHC)than those fed unsupplemented diet and 4％ aloe supplemented diet.There was a significant increase (P＜0.05) in the neutrophil to lymphocyte ratio (NLCR) within experimental groups after challenge; NLCR in aloe unsupplemented fish and those supplemented with aloe diet at 1％/kg feed increased significantly (P＜0.05) throughout challenge period; while those fed 4％ aloe supplemented diet maintained higher values at all experimental stages among groups.There was a significant correlation (P＜0.05, r =0.53) between NLCR and glucose concentration, 96 hours after challenge.Aloe had no significant effect (P＞0.05) on the survival of the fish when compared to the control; no mortality was recorded during challenge trial.Furthermore, fish fed dietary aloe at 4％/kg feed significantly reduced (P＜0.05) in total cholesterol (TC), while triacylglycerol (TG) reduced in those fed 0.5％, 2％, and 4％ aloe/kg feed compared to unsupplemented ones.High-density lipoprotein (HDL) was significantly elevated in fish fed 0.5％ and l％ aloe/kg feed compared to unsupplemented ones and no significant changes (P＞0.05) were noted in low-density lipoprotein (LDL) among test groups.Furthermore, high activities of superoxide dismutase (SOD), Catalase (CAT), and glutathione peroxide (GSH-Px) in liver tissues were observed in aloe supplemented fish compared to unsupplemented ones, before and after S.iniae challenge.Variations were also noted in malondialdehyde (MDA) activity throughout the trial, but no significant difference (P＞0.05) was observed between groups.Meanwhile, aloe supplemented fish reduced in serum aspartate and alanine aminotransferase (AST and ALT) activities before and after challenge.Overall, our results indicated that 100％ aloe powder could be potential sex reversal agent, growth promoter, appetizer, meat quality enhancer, anti-depressant, immunostimulants, antioxidant, and hepatoprotective promoter especially during disease outbreaks in tilapia culture.However, before aloe could be recommended as an all male tilapia producing technique or tilapia feed additives to improve their growth performance and other physiological parameters, more 收起