The anti-inflammatory role of lutein has been widely recognized, however, the underlying mechanism is still not fully elucidated. Hence, the effects of lutein on the intestinal health and growth performance of broilers and the action of mechanism were investigated. 288 male yellow-feathered broilers (1-day old) were randomly allocated to 3 treatment groups with 8 replicates of 12 birds each, and the control group was fed a broken rice-soybean basal diet, while the test groups were fed a basal diet added with 20 mg/kg and 40 mg/kg of lutein (LU20, LU40), respectively. The feeding trial lasted for 21 d. The results showed that 40 mg/kg lutein supplementation tended to increase ADFI (P = 0.10) and ADG (P = 0.08) of broilers. Moreover, the addition of lutein caused a decreasing trend of gene expression and concentration of proinflammatory cytokines IL-1β (P = 0.08, P = 0.10, respectively) and IL-6 (P = 0.06, P = 0.06, respectively) and also tended to decrease the gene expression of TLR4 (P = 0.09) and MyD88 (P = 0.07) while increasing gene expression and concentration of anti-inflammatory cytokines IL-4 and IL-10 (P < 0.05) in the jejunum mucosa of broilers. Additionally, lutein supplementation increased the jejunal villi height of broilers (P < 0.05) and reduced villi damage. The experiment in vitro showed that lutein treatment reduced the gene expression of IL-1β, IL-6, and IFN-γ in chicken intestinal epithelial cells (P < 0.05). However, this effect was diminished after knock-down of TLR4 or MyD88 genes using RNAi technology. In conclusion, lutein can inhibit the expression and secretion of proinflammatory cytokines in the jejunum mucosa and promote intestinal development of broilers, and the anti-inflammatory effect may be achieved by regulating TLR4/MyD88 signaling pathway.

Astaxanthin (AST), a keto carotenoid, is widely recognized for its antioxidant, anti-inflammatory, and apoptosis-regulating properties, but its effects on intestinal health have not been elucidated. Therefore, this experiment aimed to investigate the effects of astaxanthin on intestinal morphology, barrier function, mucosal immunity, and cecal flora in yellow-feathered broilers, and to explore the potential mechanisms. A total of 288 male yellow-feathered broilers (1-day-old) were randomly allocated to four groups with six replicates of 12 birds each. The control group (CON) was fed a basal diet, the test groups were fed a basal diet added with 20 mg/kg, 40 mg/kg, and 80mg/kg of astaxanthin (AST20, AST40, and AST80), respectively. The results showed that compared with the CON group, the villus height and the villus-to-crypt ratio of broiler jejunum in the astaxanthin-added group increased, while the crypt depth decreased (P < 0.05). In addition, IL-1β content and gene expression in broiler jejunal mucosa decreased, IL-6 gene expression decreased, and IL-4 content and gene expression increased (P < 0.05). The tight junction protein ZO-1 expression level in the jejunum mucosa of broilers was up-regulated, and the content of serum D-lactic acid was decreased (P < 0.05). Besides, the α-diversity and β-diversity analyses showed that astaxanthin regulated both the diversity and the structure of the intestinal flora of broilers. After multiple comparative analyses, the relative abundance of norank_f__Eubacterium_coprostanoligenes_group, Lachnospiraceae NC2004_group, and unclassified_p_Firmicutes increased in the AST20 group compared to the CON group, while that of Ruminococcus_torques_group in the AST80 group decreased (P < 0.05). Therefore, AST can regulate the immune function of broiler intestinal mucosa, improve intestinal morphology and structure, and then influence intestinal permeability. It also has a considerable regulatory effect on the diversity and structure of broiler intestinal flora and plays a multifaceted role in maintaining broiler intestinal health.

The purpose of this experiment was to investigate the effects of Hot Water Extract of Juncao-substrate Ganoderma lucidum Residue (HWE-JGLR) on the immune function and intestinal health of yellow-feather broilers. In an animal feeding experiment, 288 male yellow-feather broilers (1 day old) were randomly allocated to four treatment groups with six replicates of 12 birds each. The control (CON) group was fed a basal diet. HJ-1, HJ-2, and HJ-3 were fed a basal diet supplemented with 0.25%, 0.50%, and 1.00% HWE-JGLR, respectively. The feeding trial lasted for 63 d. The results showed increased ADFI (p = 0.033) and ADG (p = 0.045) of broilers in HJ-3, compared with the CON group. Moreover, higher contents of serum IL-4 and IL-10 and gene expression of IL-4 and IL-10 in jejunum mucosa and lower contents of serum IL-1β and gene expression of IL-1β in jejunum mucosa in HJ-3 were observed (p < 0.05). Additionally, the jejunal mucosal gene expression of Claudin-1 and ZO-1 in HJ-2 and HJ-3 was higher than that in the CON group (p < 0.05). As for the microbial community, compared with the CON group, the ACE index, Shannon index, and Shannoneven index of cecal microorganisms in HJ-2 and HJ-3 were elevated (p < 0.05). PCoA analysis showed that the cecal microbial structure of broilers in HJ-2 and HJ-3 was different from the CON group (p < 0.05). In contrast with the CON group, the broilers in HJ-2 and HJ-3 possessed more abundant Desulfobacterota at the phylum level and unclassified Lachnospiraceae, norank Clostridia vadinBB60 group and Blautia spp. at the genus level, while Turicibacter spp. and Romboutsia spp. were less (p < 0.05). In conclusion, dietary supplementation with HWE-JGLR can improve growth performance, enhance body immunity and intestinal development, and maintain the cecum microflora balance of yellow-feather broilers.