Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
Poult Sci. 2021 Sep;100(9):101369. doi: 10.1016/j.psj.2021.101369. Epub 2021 Jun 30.
Compounds in microalgae-derived feed ingredients in poultry diets may improve intestinal physiology and immunity to protect against damage induced by physiological and pathogen challenges, but mechanisms are examined sparingly. The study objective was to evaluate changes to intestinal morphology, permeability, and systemic immunity in broilers fed a proprietary microalgae ingredient during 2 separate challenge studies. In study 1, two replicate 28 d battery cage trials used 200 Ross 308 broilers each (n = 400) fed a control diet ± 0.175% algae ingredient. Half of the birds were subjected to a 12 h feed restriction challenge and fluorescein isothiocyanate dextran (FITC-D) intestinal permeability assay on d 28. Study 2 used 800 broilers randomly assigned to the same dietary treatments and housed in floor pens for 42 d. At d 14, intestine and spleen samples were collected from 10 birds/ diet. Half of the remainder was orally inoculated with 10X Coccivac-B52 vaccine in a 2 × 2 factorial treatment design (diet and Eimeria inoculation). The FITC-D assay was conducted at 1, 3, 7, and 14 d post-inoculation (pi) while intestinal and spleen samples were collected at 3, 7, 14, and 28 dpi for histomorphology and flow cytometric immune cell assessment. Study 1 validated intestinal leakage via FITC-D absorbance induced by feed restriction but showed no algae-associated protective effects. In study 2, algae preserved intestinal integrity during coccidiosis (P = 0.04) and simultaneously protected jejunal villus height as early as 7dpi (P < 0.0001), whereas intestinal damage resolution in control birds did not occur until 14 dpi. Algae inclusion increased splenic T cells in unchallenged broilers at d 14 by 29.6% vs. control (P < 0.0001), specifically γδ T cell populations, without impacting performance (P < 0.03). During Eimeria challenge, splenic T cells in algae-fed birds did not show evidence of recruitment to peripheral tissues, while control birds showed a 16.7% reduction compared to their uninoculated counterparts from 3 to 7 dpi (P < 0.0001). This evidence suggests the algae ingredient altered the immune response in a manner that reduced recruitment from secondary lymphoid organs in addition to protecting intestinal physiology.
在禽类日粮中使用源自微藻的饲料成分可能会改善肠道生理学和免疫力，以防止生理和病原体挑战造成的损害，但很少有研究检查其机制。本研究的目的是评估在 2 项单独的挑战研究中，饲喂专有微藻成分的肉鸡的肠道形态、通透性和全身免疫的变化。在研究 1 中，使用 2 个重复的 28 d 电池笼试验，每个试验使用 200 只 Ross 308 肉鸡（n = 400），分别饲喂对照日粮 ± 0.175%的藻类成分。一半的鸡接受 12 h 饲料限制挑战，并在第 28 天进行荧光素异硫氰酸酯葡聚糖（FITC-D）肠道通透性测定。研究 2 使用 800 只肉鸡随机分配到相同的日粮处理中，并在地板围栏中饲养 42 d。在第 14 天，从每一种日粮中收集 10 只鸡的肠道和脾脏样本。其余的一半鸡按照 2×2 因子处理设计（日粮和柔嫩艾美耳球虫接种）进行口服接种 10X Coccivac-B52 疫苗。在接种后 1、3、7 和 14 d 进行 FITC-D 测定，同时在 3、7、14 和 28 d 采集肠道和脾脏样本进行组织形态学和流式细胞术免疫细胞评估。研究 1 通过饲料限制引起的 FITC-D 吸收验证了肠道渗漏，但未显示藻类相关的保护作用。在研究 2 中，藻类在球虫病期间维持了肠道完整性（P = 0.04），并早在 7dpi 时同时保护空肠绒毛高度（P < 0.0001），而对照鸡的肠道损伤恢复直到 14 dpi 才发生。在未接种的鸡中，藻类的添加在第 14 天使脾脏 T 细胞增加了 29.6%（P < 0.0001），尤其是 γδ T 细胞群，而对性能没有影响（P < 0.03）。在柔嫩艾美耳球虫攻毒期间，饲喂藻类的鸡的脾脏 T 细胞没有证据表明从外周组织募集，而对照鸡从 3 到 7 dpi 时与未攻毒的对照相比减少了 16.7%（P < 0.0001）。这表明，藻类成分改变了免疫反应，减少了从次级淋巴器官的募集，同时保护了肠道生理学。
