| This article aims to study the effects of vitamin C and betaine on performance,muscle quality,antioxidant and immune function of broilers under cyclic heat stress.Before the experiment,1-day-old Kebao broilers were raised to 28-day-old,from which 200 healthy chickens with uniform weight were randomly divided into 5 groups.There were 4 repetitions in each group,with 10 chickens for each repetition.The control group:normal temperature control(24±1℃)+basic diet;The heat stress group:circulatory heat stress(33±1℃)+basic diet;The vitamins C added group(HSVc):cyclic heat stress(33±1℃)+ vitamin C(250mg/kg)+basic diet;The betaine added group(HSBe):cyclic heat stress(33±1℃)+beet Alkali(1000 mg/kg)+ basic diet;The combined addition group(HSVcBe):cyclic heat stress(33±1℃)+vitamin C(250 mg/kg)+betaine(1000mg/kg)+basic diet.This experiment lasted for 14 days.8 chickens were randomly selected from each group at 35 and 42 days of age,respectively,for sampling and related index detection according to the designed method.Results of the experiment are as follows:1.Effects of vitamin C and betaine on the growth performance of broilers under cyclic heat stressAt the age of 35 days,compared with the control group,the average daily feed intake,average daily weight gain of chickens in the HS group were significantly reduced(P<0.05).And compared with the HS group,the average daily weight gain of the HSBe group and the HSVcBe group were significantly increased(P<0.05).At the age of 42 days,compared with the control group,the average daily food intake,average daily weight gain of chickens in the HS group were significantly reduced,while the feed weight ratio was significantly increased(P<0.05).And compared with the HS group,the average daily weight gain of chickens from the HSVcBe group increased significantly(P<0.05).2.Effects of vitamin C and betaine on slaughter performance of broilers under cyclic heat stressAt the age of 35 days,compared with the control group,the slaughter rate,total clean-chamber rate,chest muscle rate and lean meat rate of chickens in the HS group were all(P<0.05),while the abdominal fat rate was significantly increased(P<0.05).Compared with the HS group,the total clean chamber rate of chickens from the HSBe group was significantly increased(P<0.05);the slaughter rate,semi-clean chamber rate and total clean chamber rate of chickens in the HSVcBe group were significantly increased(P<0.05).At the age of 42 days,compared with the control group,the semi-clean chest rate and chest muscle rate of chickens in the HS group were significantly reduced,while the abdominal fat rate was significantly increased(P<0.05).Compared with the HS group,the abdominal fat rate of chickens in the HSBe group was significantly reduced(P<0.05);the slaughter rate,semi-clean chamber rate and chest muscle rate of chickens in the HSVcBe group were significantly increased,while the abdominal fat rate was significantly reduced(P<0.05).3.Effects of vitamin C and betaine on muscle quality of broilers under cyclic heat stress3.1 Effects of vitamin C and betaine on muscle quality of chest muscle of broilers under cyclic heat stressAt the age of 35 days,compared with the control group,the shear force of chest muscle in the HS group was significantly increased,while the redness of meat was significantly decreased(P<0.05).Compared with the HS group,the shear force of chest muscle in the HSBe group and the HSVcBe group was significantly reduced,while the redness and pH of meat were significantly increased(P<0.05).At the age of 42 days,compared with the control group,the shear force of chest muscle from the HS group was significantly increased and the redness was significantly reduced.Compared with the HS group,the shear force of chest muscle from the HSVc group was significantly reduced;the shear force and dripping loss of chest muscle from the HSBe group and HSVcBe group were significantly reduced(P<0.05),while the redness and pH were significantly increased(P<0.05).3.2 Effects of vitamin C and betaine on muscle quality of leg muscle of broilers under cyclic heat stressAt the age of 35 days,compared with the control group,the shear force of leg muscle from the HS group was significantly increased,while redness and pH of the meat were significantly reduced(P<0.05).Compared with the HS group,the shear force of leg muscle in the HSVc group was significantly reduced;the shear force of leg muscle in the HSBe and HSVcBe groups was significantly reduced,and the color of meat a was significantly increased(P<0.05).At the age of 42 days,compared with the control group,the cooked meat rate and redness of leg muscle from the HS group were significantly reduced,while the shear force was significantly increased(P<0.05).Compared with the HS group,the shear force of leg muscle in the HSVc group was significantly reduced;the shear force in the HSBe group was significantly reduced,but redness was significantly increased(P<0.05);the cooked meat rate,redness and the shear force in the HSVcBe group were significantly increased(P<0.05).4.Effects of vitamin C and betaine on blood biochemical indexes of broilers under circulating heat stress4.1 Effects of vitamin C and betaine on serum hepatorenal index of broilers under circulating heat stressCompared with the control group,the blood levels of AST,T-BIL and UA of 35-day-old chickens from the HS group were significantly increased.At the age of 42 days,compared with the control group,the blood levels of D-BIL and UA in the HS group were significantly increased(P<0.05);compared with the HS group,the content of UA in vitamin C,HSBe and HSVcBe group was significantly reduced(P<0.05).4.2 Effects of vitamin C and betaine on the contents of blood glucose and inorganic salt in broilers under circulating heat stressAt the age of 35 days,compared with the control group,the content of GLU in the HS group was significantly increased,and the contents of Ca,P and Mg were significantly reduced(P<0.05).Compared with the HS group,the contents of Ca,P and Mg in vitamin C,HSBe and HSVcBe groups were significantly increased(P<0.05).4.3 Effects of vitamin C and betaine on the content of serum lipid of broilers under circulating heat stressCompared with the control group,the contents of TC and LDL-C of 35-day-old chickens in the HS group were significantly increased(P<0.05 or P<0.01).5.Effects of vitamin C and betaine on antioxidant function of broilers under cyclic heat stress5.1 Effects of vitamin C and betaine on Antioxidant function of serum of broilers under cyclic heat stressAt the age of 35 days,compared with the control group,the serum level of T-AOC and the activity of T-SOD in the HS group were significantly reduced(P<0.05),while MDA content was significantly increased(P<0.05).Compared with the HS group,the serum level of T-AOC and the activity of T-SOD in the HSVc,HSBe and HSVcBe groups were significantly increased(P<0.05),while the MDA content was significantly reduced(P<0.05).At the age of 42 days,compared with the control group,the serum level of T-AOC and the activity of T-SOD in the HS group were significantly reduced(P<0.05),while MDA content was significantly increased(P<0.05).Compared with the HS group,the serum level of T-AOC and the activity of T-SOD in the HSVc,HSBe and HSVcBe groups were significantly increased(P<0.05).5.2 Effects of vitamin C and betaine on antioxidant function of chicken liver of broilers under cyclic heat stressAt the age of 35 days,compared with the control group,the level of T-AOC and the activity of T-SOD in the HS group were significantly reduced,while the content of MDA increased(P<0.05).Compared with the HS group,the level of T-AOC and the activity of T-SOD in the liver from the HSVc,HSBe and HSVcBe groups were significantly increased(P<0.05).At the age of 42 days,compared with the control group,the level of T-AOC in the HS group was significantly reduced(P<0.05).Compared with the HS group,the level of T-AOC in the liver from the HSVc,HSBe and HSVcBe groups was significantly increased(P<0.05).5.3 Effects of vitamin C and betaine on antioxidant function of immune organs in broilers under cyclic heat stressAt the age of 35 and 42 days,compared with the control group,the level of T-AOC and the activity of T-SOD of bursa of fabricius in the HS group were significantly reduced(P<0.05),while the content of MDA significantly increased(P<0.05);Compared with the HS group,the level of T-AOC and the activity of T-SOD of bursa of fabricius in the HSVc group were significantly increased(P<0.05),while the content of MDA was significantly descreased(P<0.05);the level of T-AOC inscreased and the content of MDA descreased in the HSBe group(P<0.05);the level of T-AOC and the activity of T-SOD were significantly increased(P<0.05)while the content of MDA descreased(P<0.05).At the age of 35 days,compared with the control group,the level of T-AOC and the activity of T-SOD of spleen in the HS group were significantly reduced(P<0.05).Compared with the HS group,the level of T-AOC in the spleen in the HSBe and HSVcBe groups was significantly increased(P<0.05).At the age of 42 days,compared with the HS group,the activity of T-SOD of the spleen in the control,HSVc,HSBe and HSVcBe groups were significantly increased(P<0.05).At the age of 35 days,the content of MDA in thymus in the HS group was significantly higher than that in the control group(P<0.05).Compared with the HS group,the content of MDA in the spleen from the HSBe and HSVcBe groups was significantly reduced(P<0.05).At the age of 42 days,compared with the control group,the content of MDA in the spleen was significantly increased in the HS group(P<0.05).Compared with the HS group,the content of MDA in the spleen feom the HSVc group was significantly reduced(P<0.05),while the activity of T-SOD in the spleen from the HSBe and HSVcBe groups was significantly increased and the content of MDA was significantly reduced(P<0.05).6.Effects of vitamin C and betaine on immune function of broilers under cyclic heat stressAt 35 days of age,compared with the control group,the weight and index of thymus and bursa of fabricius of chickens from the HS group decreased significantly(P<0.05).Compared with the HS group,the weight and index of thymus in the group HSVc increased significantly(P<0.05);the weight of thymus in the HSBe group increased significantly(P<0.05);the weight of thymus and the antibody level of SRBC both increased significantly(P<0.05)in the HSVcBe group.At the age of 42 days,SRBC antibody level descreased(P<0.05 or P<0.01),and the weight of thymus,bursa and spleen and the index of thymus and bursa were all significantly reduced in the HS group compared with the control group(P<0.05).Compared with the HS group,SRBC antibody level(P<0.05 or P<0.01),the weight of thymus and fabricius bursa,and index of thymus were significantly increased in the HSVc group(P<0.05);SRBC antibody level were significantly increased in the HSBe group(P<0.05 or P<0.01);SRBC antibody levels(P<0.05 or P<0.01),thymus and bursa weight increased significantly in the HSVcBe group(P<0.05).Conclusion:Based on the above results,heat stress reduces broiler performance,muscle quality,and antioxidant levels,resulting in blood biochemical metabolic disorders and immunosuppression.The addition of vitamin C and betaine improves the production performance,meat quality,antioxidant level,Immune Organ Index,and promotes the body’s immune response.The combination of vitamin C and betaine has the effect of relieving heat stress is more significant. |
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