Effects Of Earthworm Fluid On Growth Performance,Intestinal Barrier Function And Immune Performance Of Heat-stressed Broilers

Heat stress is a highly concerned problem in modern livestock and poultry breeding.Earthworm fluid is a liquid substance extracted from fresh earthworm.earthworm fluid can improve immunity,but the application of earthworm fluid in broilers under heat stress is rarely reported.In this study,817 broilers were used as experimental subjects to investigate the effects of different levels of earthworm liquid on heat stress in growth performance,intestinal barrier function and immune function.A total of 350 15-day-old 817 broiler cocks were raised to 21 days of age with routine feeding and immunization.288 healthy animals with similar body weight were randomly divided into four treatment groups with the supplemental levels of earthworm liquid of0,0.5%,2% and 3.5%,respectively.Each treatment group had 6 replicates with 12 chickens per replicate.The experiment lasted for 21 days and temperature and humidity were recorded every day.At 42 days of age,growth performance,serum biochemical indexes,intestinal mucosal permeability,liver and intestinal innate immune related gene expression were measured.The test results are as follows:1.Compared with the control group,diet supplemented with 3.5% earthworm liquid significantly increased the average daily feed intake of broilers under heat stress(P < 0.05).Diets supplemented with different levels of earthworm liquid significantly decreased the level of serum AST(P < 0.05)and extremely significantly increased the CAT enzyme activity in ileum mucosa(P < 0.01).The supplementation of 2% earthworm solution significantly decreased the level of MDA in serum(P < 0.05),and the supplementation of 2% and 3.5% earthworm solution extremely significantly decreased the activity of GSHPx in serum(P < 0.001).Supplementation of 0.5% and 2% earthworm liquid significantly decreased MDA level in ileum mucosa(P < 0.05);Adding 0.5% earthworm liquid significantly increased the T-AOC level in ileum mucosa(P < 0.01).2.Dietary supplementation with 2% earthworm liquid significantly increased ileum villus length of broilers under heat stress(P < 0.05).The levels of D-LA in serum were significantly decreased(P < 0.05),and the levels of DAO and LPS in serum were significantly decreased(P < 0.01)by adding different levels of earthworm liquid.Dietary supplematation of 0.5% earthworm liquid significantly up-regulated the m RNA expression of Claudin-2 in ileum mucosa;Adding 2% earthworm fluid significantly up-regulated the m RNA expression levels of Claudin-2 and Occludin in jejunum mucosa(P < 0.01).3.The levels of IL-6,IFN-γ and TNF-α in serum were significantly decreased(P <0.01),and the level of IL-12 in serum was significantly decreased(P < 0.05)by adding different contents of earthworm liquid.Adding 3.5% earthworm liquid significantly decreased the levels of IL-1β and TNF-α in liver,and the m RNA expression of TNF-α in jejunum mucosa and liver(P < 0.05),and significantly increased the m RNA expression of TRAF4 in liver tissue(P < 0.01).The supplementation of 2% earthworm liquid significantly decreased the levels of IL-12 and TNF-α and the m RNA expression of TNF-αin liver(P < 0.05),and significantly increased the m RNA expression of TRAF4 in liver(P < 0.01).4.Adding 0.5% and 3.5% earthworm solution significantly down-regulated HSP70 m RNA expression in liver(P < 0.05).Adding 3.5% earthworm liquid significantly downregulated the m RNA expression of NLRP3 in ileum mucosa(P < 0.01).Adding 2%earthworm solution significantly up-regulated the m RNA expression of CATH-B1 in jejunum mucosa(P < 0.05),significantly down-regulated the m RNA expression of AVBD9 in jejunum mucosa and ileum mucosa(P < 0.05),and extremely significantly downregulated the m RNA expression of AVBD6 in ileum mucosa(P < 0.01).Adding 3.5%earthworm fluid extremely significantly down-regulated the m RNA expressions of AVBD6 and AVBD9 in jejunum mucosa and My D88 in ileum mucosa(P < 0.01),and significantly down-regulated the m RNA expressions of AVBD6 and AVBD9 in ileum mucosa(P < 0.05).The m RNA expression of CATH-B1 in ileum mucosa was significantly up-regulated(P <0.01).Adding 2% and 3.5% earthworm fluid significantly down-regulated the expression of MUC2 m RNA in ileum mucosa(P < 0.01).In summary,Earthworm fluid can improve the growth performance of broilers under heat stress to a certain extent and can scavenging lipid peroxides and free radicals,reduces systemic inflammatory response and oxidative damage caused by heat stress.It alleviates the damage of the intestinal mucosa to a certain extent,participates in the regulation of NF-κB signal,and has an improvement effect on the intestine and liver of heat-stressed broilers.