| Heat stress is one of the major environmental factors affecting livestock production.It affects the production performance,reproductive performance,and product quality by changing various physiological and biochemical reactions of animals and inhibiting the immune function of animals,it brings serious economic losses to livestock and poultry breeding.Viola yedoensis Makino is a common Chinese herb with anti-bacterial,anti-inflammatory,immunomodulatory,and antioxidant properties.This study investigated the effect of the Viola yedoensis Makino aqueous extract on spleen and thymus injury in heat stress broilers by using modern biological methods in constructing a broiler-heat stress model.Sixty one-day-old AA broilers with similar body weight and good health status were randomly divided into six groups: Group A、B、C、D、E and F,each group had two replicates,each repeat group consisted of 5 chickens.Group A was the blank control group(26 ± 1 °C),Group B was the high dose(26 ± 1 °C,4.5% Viola yedoensis Makino aqueous extract),and Group C was the heat stress(34 ± 1 °C),group D was heat stress + low dose(34 ± 1 °C,0.5% Viola yedoensis Makino aqueous extract),Group E was heat stress + middle dose(34 ± 1 °C,1.5% Viola yedoensis Makino aqueous extract),group F was heat stress + high dose(34 ± 1 °C,4.5% Viola yedoensis Makino aqueous extract),heat stress treatment of broilers from 29 days of age to 42 days of age.The effects of heat stress on immune function,oxidative stress,and apoptosis of spleen and thymus in broilers were investigated.The main content and results of this research are as follows:1.Effects of Viola yedoensis Makino aqueous extract on immune function of spleen and thymus in heat-stressed broilers : The indexes of spleen and thymus organs of broilers were significantly decreased by heat stress,and the levels of serum cortisol(Crot),Hsp70,IL-1 βand IFN-γm RNA expression in spleen and thymus tissues were significantly increased(P<0.05,P<0.01),the levels of serum immunoglobulins,ND and IBD antibodies,spleen and thymus anti-inflammatory factors(IL-4,IL-10)and m RNA expression were significantly decreased(P<0.05,P<0.01).The boundary between the spleen red pulp and the white pulp is blurred,necrotic cells are found in the parenchyma of the spleen,the boundary between the cortex and the medulla of the thymus is not obvious,the boundary between the cortex and the medulla of the thymus is blurred,and the necrotic foci and vacuoles of different sizes are distributed in the thymus,hyperemia.The levels of serum cortisol(Crot),heat shock protein 70(Hsp70),proinflammatory factor(IL-1β,IFN-γ),and m RNA expression in the spleen and thymus of heat-stressed broilers were significantly decreased by adding different concentrations of Viola yedoensis Makino aqueous extract(P<0.05,P<0.01),the contents of spleen and thymus organ index,serum immunoglobulin,Nd and IBD antibody,spleen and thymus anti-inflammatory factor(IL-4,IL-10)and m RNA expression were significantly increased(P<0.05,P<0.01),the spleen and thymus of broiler chickens were damaged by necrotic morphology,the necrotic cells in the spleen were decreased,and the vacuoles and congestion of thymus were decreased.2.Effects of Viola yedoensis Makino aqueous extract on antioxidant capacity of spleen and thymus in heat-stressed broilers:The levels of CAT,GSH,and SOD in the spleen and thymus of heat-stressed broilers were significantly lower than those in the control group(P<0.05,P<0.01),and the accumulation of MDA was obviously higher than that in the control group(P<0.01).Compared with the heat stress group,the levels of CAT,GSH,and SOD in the spleen and thymus of heat stress broilers were significantly increased by adding different concentrations of Viola yedoensis Makino aqueous extract(P<0.05,P<0.01),the accumulation of MDA in spleen and thymus was significantly decreased(P<0.05,P<0.01).3.Effect of Viola yedoensis Makino aqueous extract on apoptosis in spleen and thymus of heat-stressed broilers: Tunel method was used to detect the apoptosis of spleen and thymus in broilers.The results showed that the number of apoptotic cells in the spleen and thymus was significantly increased by heat stress compared with the blank control group,heat stress significantly increased the expression of caspase-3m RNA in the spleen and thymus,and the expression of Bax/Bcl-2 m RNA in the thymus(P<0.05,P<0.01).Compared with the heat-stress group,adding different concentrations of Viola yedoensis Makino aqueous extract reduced apoptosis of spleen and thymus cells in heat-stressed broilers The m RNA expressions of Caspase-3and BAX/BCL-2 in spleen and thymus were significantly decreased(P<0.01,P<0.05).In conclusion,Viola yedoensis Makino can inhibit apoptosis and alleviate heat stress-induced pathological changes in the spleen and thymus of immune organs of heat-stressed broilers by increasing the antioxidant capacity of the spleen and thymus,it can protect the immune function of heat stress broilers. |
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