PDF(Pubmed)
Abstract：
The primary objective of this trial was to study the effects of stress caused by stocking density in tilapia (Oreochromis niloticus) cultured in the in-pond raceway system (IPRS). Fingerlings (Initial body weight = 30.00 ± 1.20 g) were reared at different stocking densities i.e. low stocking density (n = 13,000; 1.77 kg/m3), medium stocking density (MSD) (n = 17,000; 2.32 kg/m3), and high stocking density (HSD) (n = 21,000; 2.86 kg/m3), all confined within the raceways of the IPRS. Each group was studied in triplicates. The observed growth revealed a regression in the HSD treatment, evident in its reduced weight gain per fish per day, in contrast to other treatments. Survival rate across all treatments was above 99%. Notably, the HSD treatment exhibited an elevated level of cortisol; however, this intensified crowding stress did not significantly undermine the nutritional value of the fish in HSD and other experimental treatments. Furthermore, an elevation in the levels of superoxide dismutase, catalase, and glutathione peroxidase was noted within the HSD treatment in comparison to the other treatments to reduce the damage caused by reactive oxygen species. As the trial proceeded, functions of digestive enzymes like amylase, protease, and lipase diminished consistently across all treatments. This could possibly signify a deliberate redirection of energy resources toward stress alleviation rather than the usual digestive processes. In summation, it can be reasonably deduced that a stocking density of approximately 2.32 kg/m3 (MSD) emerges as the optimal threshold for effectively cultivating tilapia within an intensive aquaculture framework.
摘要：
该试验的主要目的是研究在池塘内跑道系统（IPRS）中培养的罗非鱼（Oreochromisniloticus）的放养密度引起的胁迫的影响。鱼种（初始体重=30.00±1.20g）以不同的放养密度饲养，即低放养密度（n=13,000；1.77kg/m3），中等放养密度（MSD）（n=17,000；2.32kg/m3），和高放养密度（HSD）（n=21,000；2.86kg/m3），全部限制在IPRS的滚道内。每组一式三份进行研究。观察到的生长显示HSD治疗的消退，每天每条鱼的体重增加减少，与其他治疗相反。所有治疗的存活率均在99%以上。值得注意的是,HSD治疗显示皮质醇水平升高；然而，在HSD和其他实验处理中，这种加剧的拥挤压力并未显着破坏鱼类的营养价值。此外，超氧化物歧化酶水平的升高，过氧化氢酶,与其他处理相比，在HSD处理中注意到谷胱甘肽过氧化物酶，以减少由活性氧引起的损害。随着审判的进行,淀粉酶等消化酶的功能，蛋白酶，在所有治疗中，脂肪酶持续减少。这可能意味着有意将能源转向缓解压力而不是通常的消化过程。总之，可以合理地推断，大约2.32kg/m3（MSD）的放养密度是在集约化水产养殖框架内有效培养罗非鱼的最佳阈值。
