This study evaluated the effect of carrageenan from Kappaphycus alvarezii on the growth and health parameters of the Pacific white shrimp Litopenaeus vannamei. Shrimp (initial weight 4.5 ± 0.5 g) were farmed in 800 L tanks for five weeks, at a density of 30 shrimp tank^‐1, under controlled temperature (28.5 °C), constant aeration, 100% water exchange four times week^‐1, and fed four times day^‐1. Five experimental diets containing 0%, 0.5%, 1.0%, 1.5%, and 2.0% of carrageenan were used and followed a complete randomized design (all in triplicate). After the 5-week feeding trial period, we assessed shrimp growth parameters (survival, feed conversion, total, weekly, and final weight gain) as well as immunological and gut microbiota profiles. A total of 30 shrimp from each feeding treatment were infected with a inoculum of the white spot syndrome virus (WSSV), and the resulting cumulative mortality was monitored for 96 h. WSSV infection results showed that shrimp that received carrageenan supplementation had higher survival rates (80%, 75%, 85%, and 70%, respectively, increasing carrageenan, 0.5 to 2%) compared to the control group (45%). No significant differences in weight gain and food conversion were observed among the feeding treatments relative to the control diet. Final weight varied from 8.50 g to 10.30 g, and the food conversion rate from 1.42 to 1.67. Also, no significant differences were found in intestinal microbiota and immunological parameters. Metagenomic analysis showed that adding 0.5% of carrageenan in the diet caused an increase in the relative abundance of an unassigned bacterium (from Rhodobacteraceae family) and bacteria from two other families, Rubritaleaceae and Caldilineaceae, with 1.0% and 1.5% addition levels, respectively. Adding low levels of carrageenan (up to 1.5%) to the feed of the Pacific white shrimp might benefit their microbiota composition as well as their capacity to respond to WSSV infection, without causing any loss in growth performance and health status.

本研究评估了来自Kappaphycus alvarezii的角叉菜胶对南美白对虾的生长和健康参数的影响。对虾（初重 4.5 ± 0.5 g）在 800 L 水箱中养殖 5 周，密度为 30 只虾箱^-1，控制温度（28.5 °C），持续曝气，100% 换水，每周 4 次^-1 , 一天喂四次^‐1. 使用含有 0%、0.5%、1.0%、1.5% 和 2.0% 角叉菜胶的五种实验饮食，并遵循完整的随机设计（均一式三份）。在 5 周的饲养试验期后，我们评估了虾的生长参数（存活率、饲料转化率、总增重、每周增重和最终增重）以及免疫学和肠道微生物群特征。来自每个饲养处理的总共 30 只虾感染了白斑综合征病毒 (WSSV) 的接种物，并监测了 96 小时的累积死亡率。WSSV 感染结果显示，与对照组（45%）相比，接受角叉菜胶补充的虾具有更高的存活率（分别为 80%、75%、85% 和 70%，增加角叉菜胶 0.5% 至 2%）。相对于对照饮食，在饲喂处理之间没有观察到体重增加和食物转化的显着差异。最终重量从 8.50 克到 10.30 克不等，食物转化率从 1.42 到 1.67。此外，肠道微生物群和免疫学参数没有发现显着差异。宏基因组分析表明，在饮食中添加 0.5% 的角叉菜胶会导致未指定细菌（来自红杆菌科）和来自其他两个科（红杆菌科和 Caldilineaceae）的细菌的相对丰度增加，添加水平分别为 1.0% 和 1.5%。在太平洋白虾的饲料中添加低水平的角叉菜胶（最多 1.5%）可能有益于它们的微生物群组成以及它们对 WSSV 感染的反应能力，