急性免疫应激对肉仔鸡血液指标及肌肉脂质过氧化的影响

细菌脂多糖(Lipopolysaccharide,简称LPS)是存在于革兰氏阴性菌细胞壁外膜中的致病成分。试验利用细菌脂多糖诱导急性免疫应激,研究短期注射不同剂量细菌脂多糖对肉仔鸡血液生化指标和肌肉脂质过氧化的影响。选择80只体重相近的21日龄肉仔鸡,随机分为4组,其中3个试验组分别在21、23、25(选择3周龄的肉仔鸡连续3次隔天注射LPS引发急性免疫应激)日龄连续3次经腹腔注射LPS生理盐水稀释液,剂量为每千克体重250、500、1000μg,对照组注射等量生理盐水,试验期6d。在21、23日龄注射LPS3h后和25日龄注射LPS24h后(21、23日龄取血是检测注射LPS后3h血液指标的变化,在25日龄注射LPS24h后杀鸡测肉质指标时,也取血液测血液指标,观测血液指标随注射时间的变化趋势)取血液制备血浆、血清,测定血清细胞因子、血浆丙二醛和超氧化物歧化酶的含量;26日龄取试鸡胸肌,测定丙二醛及超氧化物歧化酶含量。结果表明:①LPS刺激显著提高了血清中细胞因子的水平(P<0.05);②LPS刺激显著提高了血浆和胸肌中丙二醛的含量(P<0.05);③低剂量LPS刺激显著降低了血浆中超氧化物歧化酶的含量(P<0.05),而高剂量LPS刺激有显著提高血浆及胸肌中超氧化物歧化酶含量的趋势(P<0.05)。     

热应激条件下内毒素对肉鸡血常规指标的影响

采用复制肉鸡热应激病例模型的方法探讨肉鸡热应激机制。选用20日龄AA肉鸡50只,随机分为对照组(20只)和试验组(30只),适应性饲养2周后进行热应激处理,检测血清中内毒素含量及血常规指标的变化。结果显示:与对照组相比,热应激可以引起试验组血清中内毒素含量极显著升高(P<0.01);同时,血液中红细胞数目先升高后显著性降低(P<0.05);白细胞数目先降低后极显著性升高(P<0.01)。结果表明:肉鸡在热应激条件下内毒素含量的变化对机体产生了危害。     

Effects of testosterone on lipid peroxidation, lipid profiles and some coagulation parameters in rabbits

The purpose of this study was to investigate the effects of testosterone on some risk factors of atherosclerosis. Twenty-four male New Zealand white rabbits were randomly divided into three groups of eight. The first group was used as control. Second group was injected with 10 mg of testosterone propionate. Third group was castrated bilaterally. At the end of 6 weeks, lipid peroxidation (LPO), lipid profile, fibrinogen (FBN) level and coagulation parameters were evaluated. Testosterone administration decreased the level of high-density lipoprotein cholesterol (HDL-C), while castration increased this level (P < 0.05). Triglyceride (TG) and total cholesterol (TC) levels in the castration group were significantly higher (P < 0.05) than those in the testosterone group. The ratio of HDL-C:low-density lipoprotein cholesterol (LDL-C) decreased, while TC:HDL-C ratio increased (P < 0.05) in the testosterone group. No significant differences were found in the LDL-C and FBN levels among groups. However, there was a tendency for higher FBN level in the testosterone group. Testosterone administration resulted in an increase in the level of LPO (P < 0.05). Clotting time and prothrombin time prolonged in the castration group compared with testosterone group (P < 0.05). As a result, testosterone has exacerbating effect on atherosclerosis risk factors including lipid profile, LPO, FBN and coagulation system.     

热应激对肉仔鸡血液生化指标影响的观察

应激对集约化肉鸡生产起着严重的制约作用 ,尤其高温 ,使肉鸡生产性能、免疫力下降、发病率和死亡率显著升高 [1]。但是有关热应激机理的研究结论并不完全相同[2 ] ,为此 ,本研究以高温作为应激原 ,系统的研究了热应激肉仔鸡血清激素、酶、蛋白质和离子的动态变化 ,探讨热应激对机体代谢、电解质平衡及内分泌机能的影响 ,以期为肉仔鸡热应激的防制提供理论依据。1　材料与方法1 .1　试验动物与分组　 1 4日龄健康 AA肉仔鸡1 2 0只 ,由莱芜市种鸡厂提供。雏鸡全部饲养于 1 0m2 封闭试验动物房的层叠笼中 ,供给全价饲料 ,自由饮水和采食。按…     

氯化铵对肉仔鸡热应激的影响

通过离子平衡途径,在肉仔鸡日粮中添加氯化铵,观察其对家禽热应激的影响。将270只1日龄艾维茵肉雏鸡随机分为5个处理,每处理设3个重复,试验持续到5周龄。试验模拟夏季高温环境,全期人工控温28～35℃。1～28日龄进行饲养试验;29～34日龄进行代谢试验。5组试验日粮为:Ⅰ为正对照组,21%CP;Ⅱ为Ⅰ组日粮+0 62%氯化铵;Ⅲ为负对照组,19%CP;Ⅳ为Ⅲ组日粮+0 62%氯化铵;Ⅴ为Ⅲ组日粮+1 00%氯化铵。试验结果表明:Ⅱ、Ⅲ、Ⅳ和Ⅴ组肉仔鸡期末体重、日增重、采食量和饲料转化率与对照组无显著差异,Ⅴ组21日龄体重显著降低(P<0 05);Ⅱ和Ⅴ组显著提高CP、Ca和P的表观代谢率(P<0 05),Ⅴ组P除外;Ⅴ组粪便含水率明显增加(P<0 01);Ⅲ、Ⅳ组与对照组代谢指标差异不显著。     

Effects of heat stress on growth, some blood variables and lipid oxidation in broilers exposed to high temperature at an early age

1. This study was conducted to determine metabolic and physiological responses of 2 commercial broiler strains, Hubbard (H) and Cobb (C), exposed to an ambient temperature of 38 degrees +/- 1 degree C for 2 h at 14 and 15 d of age. 2. Exposure to high temperature at an early age resulted in weight loss in strain C, which was not compensated for by 35 d of age but there was no weight loss in strain H. 3. Exposure of broilers to heat stress (38 degrees +/- 1 degree C) at 35 d of age resulted in an increase in rectal temperature, regardless of previously high temperature experience but acid-base balance and haematocrit values were not affected by heat stress. 4. Malondialdehyde concentration was higher in unexposed birds than in previously exposed ones and did not significantly differ between strains.     

玉米赤霉烯酮对肉鸡血液生化指标、肝脏氧化损伤及毒素残留的影响

试验旨在研究玉米赤霉烯酮(ZEA)对肉鸡血清指标、肝脏氧化损伤及毒素残留的影响。将120只1日龄肉鸡随机分成2组,每组设6个重复,每个重复10只。对照组饲喂基础日粮,攻毒组在基础日粮中添加2 mg/kg的ZEA。结果表明,ZEA攻毒使肉鸡血清总蛋白和白蛋白显著降低,天冬氨酸转氨酶、丙氨酸转氨酶、碱性磷酸酶显著上升;ZEA对血清IgA、IgM、IgG及细胞因子IL-2、IL-5、TNF-α水平无显著影响;ZEA使肉鸡肝脏总超氧化物歧化酶和谷胱甘肽过氧化酶活性降低,还原性谷胱甘肽含量下降,丙二醛含量升高;ZEA攻毒组肉鸡肝脏的残留量显著上升。结果提示,ZEA可影响肉鸡血清代谢物水平,造成肝脏氧化损伤,提高肝脏中残留量。     

氯化铵对肉鸡热应激的影响

热应激给夏季肉鸡生产带来极大困扰。过高的温度使肉鸡生理机能紊乱,呼吸加快,采食量降低,饮水量增加,血液中钾(K)、钠(Na)、钙(Ca)、磷(P)和氯(Cl)离子浓度发生变化,导致肉鸡营养物质摄入量下降,生长减缓,抵抗力降低,死亡率增加(Smith,1 987;傅玲玉等,1 998;田允波,2 0 0 0 )。本试验模拟夏季高温环境,在肉鸡日粮中加入0 62 %和1 0 0 %两个水平的氯化铵(NH4 Cl) ,并设计低粗蛋白质(CP)日粮,观察其对1～5周龄肉鸡生产性能和饲料表观代谢率的影响。1　材料与方法1 1　试验地点和时间　试验在深圳康达尔(高陵)饲料有限公司饲料研发基…     

Effect of copper deficiency on blood lipid profile and haematological parameters in broilers

The aim of the study was to observe the changes in haematological parameters and blood lipid profile through copper (Cu) deficiency. Eighty broiler chicks were used in the study. The chicks were separated into two equal groups (n = 40), feed treatment according to the groups started on day 7. The animals in the control group were fed with normal feed. Those in the Cu-deficient group were fed with feed that did not contain supplemental Cu. Blood samples were taken from all the animals on days 7, 21 and 49. Fibrinogen and prothrombin time were assayed in plasma; total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol (LDL-cholesterol), triglyceride and ceruloplasmin were assayed in sera; and haematocrit and thrombocyte levels were assayed in the blood samples. Total cholesterol, triglyceride and LDL-cholesterol levels were significantly higher in the Cu-deficient group than in the control group. Serum ceruloplasmin levels were lower in the Cu-deficient group than in the control group. Prothrombin time was higher in the Cu-deficient group than in the control group. Haematocrit levels were lower in the Cu-deficient group than in the control group. It was concluded that Cu deficiency created hypertriglyceridaemia, hypercholesterolaemia, insufficient growth and anaemia in broilers.     

Influence of shearing on oxidative stress and some physiological parameters in ewes

The aim of the present study was to evaluate the effect of shearing on physiological and oxidative stress parameters in ewes. Twenty Comisana ewes were used and divided into two groups. Ten ewes were left unshorn as a control group (Group A) and 10 ewes were shorn (Group B). All measurements were taken before and after shearing, and repeated 8 h after shearing and 1, 2, 3, 4, 5, 10 and 15 days after shearing. Reactive oxygen species (dROMs), antioxidant barrier (oxy‐adsorbent), thiol antioxidant barrier (SHp) and packed cell volume (PCV) were assessed in blood samples collected by means of jugular venipuncture. Rectal temperature (RT), respiratory rate (RR) and heart rate (HR) were also measured. Two‐way repeated measures analysis of variance (ANOVA), followed by Bonferroni's test, was used for the assessment of significant effects due to shearing and time. The statistical analysis showed significant increases (P < 0.01) of dROMs, oxy‐adsorbent, SHp, and a significant decrease (P < 0.01) of RT and RR associated with time and shearing. Our results indicate that shearing causes a change in the ewe's homeostatic balance that leads to oxidative stress.     

Effect of resveratrol on growth performance,rectal temperature and serum parameters of yellow‐feather broilers under heat stress

This study investigated the effect of dietary resveratrol supplementation on growth performance, rectal temperature, and serum parameters of yellow‐feather broilers under heat stress. A total of 480 yellow‐feather broilers (28‐day‐old) were randomly allotted to five groups with six replicates. A thermoneutral group (TN) (24 ± 2°C) received a basal diet and another four heat‐stressed groups (37 ± 2°C for 8 hr/day and 24 ± 2°C for the remaining time) were fed the basal diet or basal diet with 200, 350, and 500 mg/kg resveratrol for 14 consecutive days. The results revealed that resveratrol supplementation improved average daily gain (p = 0.001), and decreased (p < 0.05) rectal temperature from d 3 when compared with heat‐stressed group without resveratrol. In addition, supplementation with resveratrol at 350 or 500 mg/kg lowered (p < 0.05) the contents of corticosterone, adrenocorticotropic hormone, cholesterol, triglycerides, uric acid, malonaldehyde, and activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, increased (p < 0.05) the levels of triiodothyronine, the ratio of triiodothyronine to thyroxine, total protein, glutathione, and activities of alkaline phosphatase, total superoxide dismutase, catalase, and glutathione peroxidase, though with few fluctuation. In conclusion, supplementation with resveratrol can improve the growth performance by positively regulating serum metabolic parameters and alleviating tissue oxidant damage of broilers under heat stress.     

Effects of enzymatically treated Artemisia annua L. on growth performance and some blood parameters of broilers exposed to heat stress

To evaluate the effects of enzymatically treated Artemisia annua L. (EA) on growth performance and some blood parameters of broilers exposed to heat stress (HS), 320 22‐day‐old Arbor Acres male broilers were randomly allotted into five groups with eight replicates of eight birds each. Broilers in the control group were housed at 22 ± 1°C and fed the basal diet. Broilers in the HS, HS‐EA_0.75, HS‐EA_1.00 and HS‐EA_1.25 groups were reared under HS (34 ± 1°C for 8 h/day and 22 ± 1°C for 16 h/day), and fed basal diet with 0, 0.75, 1.00 and 1.25 g/kg EA, respectively. The experiment ended at 42 days. Dietary 1.00 and 1.25 g/kg EA decreased blood pH and elevated body weight gain, feed intake and carcass yield compared to the HS group. Broilers fed EA diets had lower serum concentrations of malondialdehyde and corticosterone and activities of alanine aminotransferase and aspartate aminotransferase, and higher serum total superoxide dismutase activity, tri‐iodothyronine concentration and tri‐iodothyronine/thyroxine than the HS group. Serum catalase activity in HS‐EA_1.00 and HS‐EA_1.25 groups and activity to inhibit hydroxyl in the HS‐EA_1.00 group were higher than the HS group. In conclusion, dietary 0.75–1.25 g/kg EA addition alleviated HS induced impairments in broilers.     

溶血卵磷脂对肉仔鸡脂类代谢的影响

选200羽1日龄AA肉仔鸡,随机分成对照组和试验组(每组10个重复),试验组日粮添加0.1%溶血卵磷脂,研究溶血卵磷脂对肉鸡脂类代谢的影响。结果表明:溶血卵磷脂降低肝脏系数和肝脂率(P>0.05)、血清总甘油三酯与低密度脂蛋白胆固醇(LDL-C)(P>0.05)、LDL-C/HDL-C和葡萄糖含量(P<0.05),提高高密度脂蛋白胆固醇(HDL-C)和游离脂肪酸含量(P<0.05),上调肉仔鸡肝脏载脂蛋白B(P<0.01)和脂肪酸合成酶(P=0.155)mRNA表达水平;而对肉仔鸡的42日龄体重、腹脂率、皮下脂肪厚、肌间脂肪厚、腿肌和胸肌含脂率以及血清总胆固醇、三碘甲腺原氨酸、四碘甲腺原氨酸、促甲状腺激素刺激激素和胰岛素含量均无显著影响(P>0.05)。结果提示:溶血卵磷脂对肉仔鸡有减少肝脂肪沉积及降血脂作用。     

Induction of oxidative stress and lipid peroxidation in rats chronically exposed to cypermethrin through dermal application

Present study was undertaken to study the effect of cypermethrin on oxidative stress after chronic dermal application. The insecticide was applied dermally at 50 mg/kg body weight in different groups of Wistar rats of either sex weighing 150~200 g. Significant (p < 0.05) increase in catalase activity was observed after 30 days of exposure. However, the superoxide dismutase activity declined significantly after 60 days of exposure. The activity of glutathione peroxidase and blood glutathione levels declined significantly (p < 0.05) after 30 days of cypermethrin dermal application. However, the activity of glutathione S-transferase increased significantly (p < 0.05) in all groups after 60 days of dermal exposure. Significant increase in lipid peroxidation was observed from 30 days onwards and reached a peak after 120 days of application.     

酸枣仁皂甙对热应激肉用仔鸡生产性能、消化道和免疫器官的影响

为探明酸枣仁皂苷对肉仔鸡的抗热应激作用,将225只1日龄AA肉雏仔鸡公母混合随机分成5组,每组3个重复,每重复15只。对照组饲喂基础日粮,处理1～4组在基础饲粮中分别添加0.5,1.0,1.5和2.0 mg/kg的酸枣仁皂苷。1～3周龄采用常规饲养管理,4周龄时开始进行为期1周的(34±1)℃热应激处理。结果:0.5和1.0 mg/kg添加水平极显著提高3周龄肉仔鸡日增重(P<0.01),4个水平的酸枣仁皂苷对热应激肉仔鸡的平均日增重、采食量和饲料转化率均有改善作用,以0.5和1.0 mg/kg添加水平最佳(P<0.01)。饲粮中添加0.5 mg/kg酸枣仁皂苷显著提高热应激肉仔鸡的屠宰率、半净膛率和全净膛率(P<0.05),极显著降低皮下脂肪厚(P<0.01)。酸枣仁皂苷对热应激肉仔鸡的腿比例、腿肌率、胸肌率、腹脂率、腺胃率、肌胃率、脾脏率、十二指肠率、空肠率、回肠率、盲肠率、法氏囊率和胸腺率均无显著影响(P>0.05)。总之,1～3周龄肉仔鸡饲粮中添加酸枣仁皂苷,可提高采食量和日增重;34℃热应激下添加酸枣仁皂苷,可提高平均日增重、采食量和饲料转化率,改善胴体品质;酸枣仁皂苷较理想的添加水平为0.5～1.0 mg/kg。     

Lipid peroxidation as the additional indicator of transport stress in broilers

Stressful conditions (transport, temperature fluctuations, infections and excessive crowding) lead to dysfunction of immunological mechanisms in birds. They influence the lipid balance what manifests itself through the increase of the malonodialdehyde (MDA) level, reacting with the 2-thiobarbituric acid (TBA), what is an indicator of lipid peroxidation. In the case of birds, the classical indicator of the stressful reaction is the heterophile/lymphocyte ratio (H/L), which changes depending on the stress intensity. The present study defined the influence of road transport on lipid peroxidation process as the additional indicator of stress in broilers. The investigation was conducted on 10 broilers Ross 308 (39 days old), which were transported on the distance of 70 km. The birds were clinically healthy, free of parasites and free of Salmonella spp. infection in the beginning of the experiment. The determination of the TBA-reactive substances (TBARS) in serum was conducted according to the method proposed by Ledwozyw et al. (1986). The analysis of the results with a Student t-test showed the statistically significant difference (P < or = 0.05) in the TBA-reactive substances level before and directly after the birds transportation.     

Effect of acute heat stress on heat shock protein 70 messenger RNA and on heat shock protein expression in the liver of broilers

1. The synthesis of heat shock protein 70 (Hsp70) mRNA and the expression of Hsp70 in the liver of broiler chickens submitted to acute heat stress (35°C for 5 h) was investigated.

2. Hsp70 expression was detected by SDS‐PAGE and Western blot analysis using a polyclonal antiserum against Hsp70 of Blastocladiella emersonii. The specific signal of Hsp70 mRNA was analysed by Northern blot using as probe a Hsp70 cDNA of B. emersonii.

3. An increase in the amount of Hsp70 was detected from the first up to the fifth hour of acute heat exposure. This increase in the amount of Hsp70 was accompanied by an increase in Hsp70 mRNA which peaked at 3 h.

4. This study shows that the heat induced increase in Hsp70 mRNA and protein in broiler liver, in vivo, are time dependent, similar to that in mammals.     

Gas stunning with CO_2 affected meat color,lipid peroxidation,oxidative stress,and gene expression of mitogen-activated protein kinases,glutathione S-transferases,and Cu/Zn-superoxide dismutase in the skeletal muscles of broilers

Background: Meat color and lipid peroxidation are important traits related to meat quality. CO_2 concentration is a critical factor that can affect meat quality in the commercial use of gas stunning(GS). However, the effect and mechanism of CO_2 stunning on meat color and lipid peroxidation during long-term storage remain poorly studied. We aimed to study the effects of GS methods, especial y CO_2 concentration, on meat color and meat lipid peroxidation in broilers during long-term storage at 4 °C and to explore the potential mechanism of meat color change via lipid peroxidation and the inner lipid peroxide scavenging system.Methods: Eighteen broilers were sacrificed after exposure to one of the following gas mixtures for 90 s: 40% CO_2+21% O_2+ 39% N2(G40%), 79% CO_2+ 21% O_2(G79%), or no stunning(0% CO_2, control). Meat color, serum variables,enzyme activities, and the gene expression of mitogen-activated protein kinase(MAPK), nuclear factor-erythroid2-related factor 2(Nrf2), glutathione S-transferase(GST) and superoxide dismutase(SOD) were determined.(Continued on next page)Results: The concentrations of serum triiodothyronine(T3, P = 0.03) and the ratio of serum free triiodothyronine/free thyroxine(FT3/FT4, P 0.01) were decreased, whereas levels of serum cortisol(P 0.01) were increased in the 40%CO_2 group compared with the control group. Additionally, the thiobarbituric acid-reactive substances(TBARS)3 d(P 0.01) and TBARS6 d(P = 0.01) in breast meat and the TBARS3 din thigh meat(P 0.01) were increased in the40% CO_2 group compared with the control group. Serum T3 was negatively correlated with TBARS6 dboth in the breast and thigh meat(r =-0.63, P 0.01 and r =-0.47, P = 0.05 respectively). T3/T4 was negatively correlated with TBARS6 din the breast meat and in the thigh meat(r =-0.57, P = 0.01; and r =-0.53, P = 0.03 respectively). Compared with the control group, Lightness(L*)1 d(P = 0.03) and L*9 d(P 0.01) were increased, whereas total chromatic aberration(E*)1 d(P = 0.05) and E*3 d(P 0.01) were decreased in the breast meat of both the G40% and G79% groups. The values of yel owness(b*)3 d(P = 0.01), b*6 d(P 0.01) and E*6 d(P 0.01) in the thigh meat were lower in both the G40% and G79% groups than in the control group. In the breast muscle, the m RNA levels of c-Jun N-terminal kinase 2(JNK2, P = 0.03),GSTT1(P = 0.04), and SOD1(P = 0.05) were decreased, and the m RNA levels of JNK1(P = 0.07), Nrf2(P = 0.09), and GSTA3(P = 0.06) were slightly lower in both the G40% and G79% groups compared with the control group. However, among these genes, only the m RNA level of JNK1 was decreased in the G40% group compared with the control group and the G79% group(P = 0.03) in the thigh muscle.Conclusions: Compared with the control group, meat color quality in the breast meat was decreased, and the expression of genes in the MAPK/Nrf2/ARE(antioxidant responsive element) antioxidant pathway in breast muscle was partly suppressed by GS of both 40% and 79% CO_2. However, oxidative stress and meat lipid peroxidation during storage were aggravated by GS with 40% CO_2 compared to GS with 79% CO_2 and no GS.     

The investigation of lipid peroxidation, anti-oxidant levels and some hematological parameters in sheep naturally infested with Wohlfahrtia magnifica larvae

Wohlfahrtia magnifica is the main agent of traumatic myiasis in many central and eastern European countries as well as in the Mediterranean basin and Asian countries. The present study was aimed to investigate the effect of myiasis infestation on lipid peroxidation, antioxidant levels and several hematological parameters in the sheep naturally infested with W. magnifica larvae. A total of 38 sheep, including 19 awassi sheep naturally infested with W. magnifica larvae and 19 clinically healthy awassi sheep, were studied. The infected animals were divided into three groups depending on the number of larvae (Group 1: <50 larvae; Group 2: 50-100 larvae; Group 3: >100 larvae). In blood samples, red blood cell counts, hemoglobin, hematocrit concentration and white blood cell, neutrophil, lymphocyte, eosinophil, basophil counts, plasma malondialdehyde, erythrocyte glutathione levels and erythrocyte glutathione peroxidase activity were studied. The results revealed a marked decrease in red blood cell counts and hemoglobin concentrations along with a significant increase in white blood cell and neutrophil counts. The elevation in plasma malondialdehyde levels, a function of lipid peroxidation, established a significant difference between the control group and groups 2, 3. Decreased activity of erythrocyte glutathione peroxidase was found significant in the control group and all parasitemia. We conclude that in natural infestations with W. magnifica, as in infestation with Lucilia cuprina, there is a notable increase in inflammatory activities resulting from the movements, secretions, and toxins of the larvae and form the toxins secreted by the bacteria - which leads to an impression of anemia - and that the tissue injury results in an increase in level of free radicals in the organism.     

两种铬源对热应激肉鸡抗氧化性能的影响

本试验旨在研究两种铬源对热应激肉鸡抗氧化能力的影响。选择15日龄AA肉仔鸡180只,随机分为3组,1组高温不加铬(对照组),2组高温加酵母铬,3组高温加烟酸铬,铬添加量为3mg/kg,试验期4周(15～42d)。结果表明:日粮中添加3mg/kg铬,显著降低了28d、42d丙二醛和过氧化氢的含量(P0.05),提高了抗超氧阴离子能力、总抗氧化能力及谷胱甘肽过氧化物酶的活性(P0.05),显著提高了28d超氧化物歧化酶活性(P0.05),但对42d超氧化物歧化酶活性无显著影响(P0.05)。因此,热应激状态下,日粮中添加铬可减少脂质过氧化反应、降低过氧化产物生成、提高热应激肉鸡抗氧化能力,但两种铬源之间差异不显著。