长期以来,人们一直对在大西洋鲑鱼水产养殖中用作海虱生物防治的BallanWrasse(Labrusbergylta)的福利感到担忧。这项研究评估了增加饮食二十碳五烯酸(EPA)水平和初始条件因子(CF)对在高水温和低水温下养殖的巴兰丝的后续性能和福利的影响。在15°C下,在3个月内饲喂具有商业或高EPA水平的饮食。Follows,鱼被PIT标记,测量其CF,并分为两组,由两种处理方法的鱼组成,并在15°C或6°C下饲喂商业饮食4.5个月。根据计算的种群平均CF,将每条鱼分为高CF(≥2.7)或低CF(<2.7)鱼。饮食组成会影响储存脂质的脂肪酸谱,而不会影响巴兰鱼的生长或福利。在15°C饲养的鱼显示出更高的生长,更多的脂肪和能量储备,更少的灰分含量。在6°C饲养的鱼体重减轻,在温度试验结束时耗尽他们的体内脂质。基因表达分析显示,与6°C相比,在15°C饲养的鱼中,正生长标记(GHRα)和参与脂肪酸合成和氧化的两个基因(elovl5,cpt1)的上调以及负生长标记mstn的下调。与15°C相比,在6°C饲养的鱼显示il-6水平上调,表明对低温有增强的免疫反应。高CF的鱼表现出更好的存活率,增长,和与低CF鱼相比的性能。外部福利评分显示消瘦的患病率和严重程度更高,与15°C相比,在6°C饲养的鱼的规模损失和总和指数得分(所有测量的福利参数),与低CF相比,高CF的鱼的福利更好。皮肤组织学检查显示,在6°C饲养的鱼表皮厚度减少,与15°C饲养的鱼相比,内部和外部表皮中的粘液细胞总数较低,以及粘液细胞的不同组织,这是鱼在6°C的压力的迹象。总的来说,低水温对性能有深远的影响,BallanWrasse的外部和内部福利参数,可以被认为是可能影响消沉功效的压力源。这些发现支持季节性使用不同的清洁鱼类。高CF,但膳食EPA水平的增加似乎并没有帮助鱼类更好地应对低水温,因此在将其部署到鲑鱼网箱中之前应进行评估和考虑。本文受版权保护。保留所有权利。
Concerns have long been raised about the welfare of ballan wrasse (Labrus bergylta) used for the biological control of sea lice in Atlantic salmon (Salmo salar) aquaculture. This study assessed the effect of increased dietary eicosapentaenoic acid (EPA) levels and initial condition factor (CF) on the subsequent performance and welfare of ballan wrasse farmed in high and low water temperatures. Fish were fed a diet with either commercial or high EPA levels for 3 months at 15°C. Subsequently, fish were tagged with a passive integrated transponder, measured for their CF and divided into two groups consisting of fish from both treatments and reared for 4.5 months at either 15 or 6°C fed a commercial diet. Each fish was categorized as high (≥2.7) or low CF (<2.7) fish based on the calculated average CF of the population. Dietary composition influenced the fatty acid (FA) profile of the stored lipids without affecting the growth or welfare of ballan wrasse. Fish reared at 15°C showed higher growth, more fat and energy reserves and less ash content. Fish reared at 6°C lost weight, using up their body lipids at the end of the temperature trial. Gene expression analyses showed upregulation of the positive growth marker (GHrα) and two genes involved in the synthesis and oxidation of FAs (elovl5, cpt1) and downregulation of the negative growth marker (mstn) in fish reared at 15°C compared to those reared at 6°C. Fish reared at 6°C showed upregulated levels of il-6 compared to those reared at 15°C, suggesting an enhanced immune reaction in response to low temperature. Fish with high CF showed better survival, growth and performance compared to those with low CF. External welfare scoring showed higher prevalence and severity in emaciation, scale loss and the sum index score (of all measured welfare parameters) in fish reared at 6°C compared to those reared at 15°C and better welfare in fish with high CF compared to those with low CF. Histological examination of the skin showed that fish reared at 6°C had decreased epidermal thickness, a lower overall number of mucous cells in the inner and outer epidermis and a different organization of mucous cells compared to fish reared at 15°C, indicating stress in fish reared at 6°C. Overall, low water temperatures had profound effects on the performance and external and internal welfare parameters of ballan wrasse and can be considered a stressor likely affecting the delousing efficacy. These findings support the seasonal use of different cleaner fish species. High CF, but not increased dietary EPA levels, appeared to help fish cope better with low water temperatures and should thus be assessed and considered before deploying them in salmon cages.