间歇光照对肉鸡体内脂质过氧化作用和抗氧化酶活性的影响

低温诱发肉鸡肺动脉高压综合征（PHS）,动态观察限制光照对肉鸡PHS发病率及体内脂质过氧化作用的影响。将320羽1日龄肉鸡随机分为4组。常温组按常规饲养,24 h连续光照。3个低温组从14日龄起逐步降温诱发PHS,并于9～30日龄分别在夜间停止光照0、35、h。结果,低温组PHS发病率、右心全心比（RV/TV）、肺厚壁末梢血管百分率（%TWPV）和丙二醛（MDA）水平显著升高,而血浆超氧化物歧化酶（SOD）活性降低。限制光照组SOD活性升高而PHS发病率、RV/TV、TWPV和MDA显著降低。间歇光照组早期生长速度减慢,后期体质量得到补偿性增长,并在44日龄与连续光照组差异不显著。这一结果表明,减轻体内脂质过氧化作用,提高机体抗氧化酶活性并减轻以非肌型肺动脉肌型化为特征的肺血管重构,可能是限制光照使肉鸡PHS发病率降低的机理之一。     

早期限饲对肉鸡肺动脉高压综合征发病率、生产性能和腹脂率的影响

采用低温诱发肉鸡肺动脉高压综合征,对比观察不同的早期限饲方法对于常温和低温条件下PHS的发病率、肉鸡生产性能和腹脂率的影响。在试验1中,限饲处理组肉鸡分别于7￣14日龄或7￣21日龄每天给料8h,对照组肉鸡全程自由采食。在试验2中,限饲组肉鸡分别于7￣14日龄给予对照组肉鸡前1d饲料消耗量的60%或80%。结果表明:早期限饲能够降低肉鸡PHS的发病率,在低温条件下尤其明显;早期限饲改善了饲料效率,同时未对肉鸡的胴体品质产生显著的影响,且适当限饲不影响肉鸡的最终上市体重。这表明早期限饲是一种有效的控制肉鸡PHS的方法,值得在实际生产中推广应用。     

早期限饲对肉鸡血浆NO水平、红细胞比容和心脏指数的影响

试验测定了常温和低温下限饲肉鸡和非限饲肉鸡体内一氧化氮(NO)含量、红细胞比容(PCV)和心脏指数的变化,以探讨早期限饲降低肉鸡肺动脉高压综合征(PHS)发病率的机理。试验结果显示低温下肉鸡的PCV值、心脏指数和PHS的发病率显著升高,NO水平在低温早期显著降低,然而随着低温时间的延长,低温处理组肉鸡的血浆NO水平反而代偿性升高。早期限饲显著降低了肉鸡生长早期的红细胞压积值,并显著降低了42日龄心脏指数和PHS的发病率。限饲鸡在限饲期间血浆NO水平显著降低,但其他阶段与非限饲鸡差异不显著。这提示早期限饲能够缓解肉鸡肺动脉高压和右心肥大的产生,其机理可能与NO和PCV改变所致的血流动力学变化有关。     

腹水综合征对肉鸡肝脏、心肌和肠黏膜线粒体抗氧化能力的影响

采取分组对比的方法（对照组，肉鸡腹水征发病组，治疗组）分别检测肝组织、肠黏膜、心肌线粒体中的MDA含量，SOD、GSH—PX的活性。结果显示，发生腹水综合征的肉鸡，其肝脏、心肌和肠黏膜线粒体MDA活力呈现先显著降低（1、2周时）、后显著提高（3、4、5周时）的变化趋势（P〈0．05）而与发病组线粒体MDA活力先降后升的动态变化趋势相反，治疗组线粒体MDA的活力则呈现先升后降的趋势，最终显著阻止了自由基的产生。线粒体SOD和GSH—Px活力的变化趋势则与MDA相反。提示：肉鸡腹水综合征显著诱导了肉鸡组织细胞和线粒体的脂质过氧化作用，显著降低了肉鸡组织细胞和线粒体的抗氧化能力；药物能有效地改善这一过程。     

日粮添加VE和VC对肺动脉高压综合征患鸡自由基代谢的影响

将380只AA商品肉鸡随机分为A组100只,B、C、D和E组各70只,14日龄前常规饲养。14日龄后,B、C、D和E组舍温按每日1～2℃由25℃、逐步降至12℃,同时日粮中按1．5mg／kg的剂量添加T3以诱发肺动脉高压综合征(PHS);C、D组在日粮中分别按500、100mg／kg的剂量添加维生素C和E;而E组同时添加维生素C和E,A组仍常规饲养,至试验结束。记录每周各组鸡群的PHS发病数、平均体质量和采食量,并每周每组取10只鸡采血和扑杀,测定其红细胞压积(PCV)、血浆、肺和肝组织的超氧化物歧化酶(SOD)及脂质过氧化物的降解产物丙二醛(MDA)浓度;取心脏测定其右心室和全心室质量比(RV／TV)。结果显示,环境低温和日粮添加T3极显著增加了肉鸡PHS的发病率(P＜0．01)。C、E组的肉鸡PHS发病率以及血浆、肺和肝组织的MDA值均极显著降低(P＜0．01),血浆、肺和肝组织的SOD值均极显著增加(P＜0．01),但增重、饲料转换率、血液PCV值和心脏指数RV／TV值未发生改变;D组5周龄后的血浆MDA值则极显著降低(P＜0．01)以及血浆、肺和肝组的SOD值极显著增加(P＜0．01),而肺和肝组织的MDA值和肉鸡PHS发病率未发生改变。由此表明,日粮添加维生素C明显阻断了低温和T3条件下肉鸡体内脂质过氧化过程,有效清除了体内自由基,显著增强了体内抗氧化能力,成功防制了肉鸡PHS的发生;日粮中同时添加维生素C和E使低温加T3条件下的肉鸡体内抗氧化能力进一步加强;但维生素C或／和E未能改变在环境低温和日粮添加T3诱病条件下肉鸡的增重和饲料转换率,而日粮中单独添加维生素E则使低温加T3条件下的肉鸡体内抗氧化能力有一定的增强作用,但并未改变肉鸡PHS的发病率。     

实验性脾虚证与自由基代谢的相关性及四君子汤对其的调整作用

分别用小承气汤和利血平复制大鼠脾虚证模型，通过检测血清和心、肝、脾、肾等组织中抗氧化酶SOD和GSHP－Px的活性及脂质过氧化反应终产物MDA含量，研究脾虚证与自由基代谢的相关性及四君子汤对其影响。结果表明：两种方法复制脾虚证模型与对照组比较均表现为SOD活性显著升高（P＜0．05），GSH－Px活性显著降低（P＜0．05）；四君子汤反证治疗组与脾虚证组比较表现为SOD活性显著下降（P＜0．05），GSH－Px活性显著升高（P＜0．05），MDA含量显著降低（P＜0．05），与正常对照组接近。表明大鼠虚证动物模型与体内自由基代谢紊乱，脂质过氧化作用增强存在一定关系，健脾益气方药四君子汤能够提高体内抗氧化酶活性，拮抗自由基对生物膜的过氧化损伤，具有抗脂质过氧化损伤的作用。     

早期限饲对在常温和寒冷环境中的肉鸡生理反应、生产性能和腹水综合征发生率的影响

现代选育技术一方面选育出快速生长和高饲料效率的肉鸡,另一方面也加剧了肉鸡对腹水综合征等代谢紊乱症的易感性。腹水综合征是肉鸡死亡和肉鸡工业经济损失的主要原因。寒冷环境是腹水综合征主要触发因素,而早期限饲能够显著缓解腹水综合征和死亡的发生。然而,早期限饲、寒冷环境温度以及它们的相互作用对肉鸡生理的相互影响研究很少。为了解决这个问题,320只1日龄肉仔公鸡被分为自由采食组和限饲组两个处理组(每个组8个重复,每个重复20只鸡)。早期限饲组鸡限饲期为7日龄到14日龄。第21天时每个处理组一半的鸡(4个重复)在寒冷环境中饲养,另外一半鸡(4个重复)仍然在常温环境下饲养。在第7、14、21、28、35、42天后测定肉鸡的平均日采食量、平均日增重、和料肉比;第39和46日龄根据每个重复平均重挑选两只鸡进行屠宰并收集血样;然后计算内脏器官相对重量和右心室/总心室比率。结果显示:与常温组相比,寒冷组28-42日龄肉鸡具有更高的平均日采食量和饲料转化效率(P0.05);寒冷组累积的腹水综合症死亡率显著高于常温组(P0.001);寒冷进行限饲组肉鸡与寒冷正常饲喂组的肉鸡的腹水综合征死亡率从8.75%显著降低到1.25%(P0.001);寒冷组肉鸡右心室显著增厚,并且右心室的心脏相对重、血细胞容积和甲状腺浓度显著增高(P0.05),但是进行限饲后,这些参数没有发生显著变化(P0.05)。在冷应激的情况下,早期限饲显著降低了丙氨酸转氨酶和天门冬氨酸转氨酶的活性(P0.05);环境温度和是否限饲对血清甘油三酯、胆固醇、高密度脂蛋白和总蛋白没有显著影响(P0.05)。总之,研究结果表明,限饲通过促进内脏器官更好地发育降低腹水综合征的发生,从而更好地帮助缓解肉鸡代谢过快的压力和缓减损伤。     

硒和上互作用及对肉用鸡胰腺抗氧化功能的影响

选用健康1日龄AA肉鸡288只，随机分成9组，每组32只，试验观察期为60d；定期剖杀检测，动态观察试验鸡日粮中不同剂量硒与锌对胰腺组织主要抗氧化酶（SOD、GSH－Px及CAT）活性及脂质过氧化终末代谢产物丙二醛（MDA）含量的影响，并探讨了日粮中硒与锌相互作用对胰腺组织结构的影响。结果表明：日粮中低硒（0．08mg/kg)、低锌（34mg/kg)、高硒（5．00mg/kg)、高锌（1000mg/kg)均不同程度地使胰腺抗氧化酶活性下降，组织清除自由基能力减弱，MDA含量增高胰腺的组织结构受到损伤；日粮中添加硒0．15mg/kg、锌50mg/kg能协同提高胰腺SOD、GSH－Px、CAT的活性胰腺组织抗氧化功能，降低胰腺组织中MDA含量能保护胰腺正常组织结构免受过氧化损伤；胰腺MDA含量与SOD、GSH－Px及CAT活性均呈显著负相关，相关系数分别为－0．7046、－0．4200、－0．4263（P＜0．01）。结果显示，胰腺依赖于SOD．GSH－Px及CAT的协同作用以抑制脂质过氧化的进行。     

通过限制饲料控制肉鸡腹水

饲料限制已被认为是减少肉鸡腹水综合征(AS)发病率的一种有效方法.墨西哥Morelice研究所进行的一系列试验说明,采用几种限料技术在把体重下降控制在最小限度的同时可减少肉鸡腹水发病率.在开始的试验中,饲料供给方式或自由采食(即饱饲),8小时/天,或比饱饲减小10%以下.在限料试验中,腹水综合征的发病率明显减少,但体增重下降的程度也较严重.     

限饲对肉鸡抗氧化水平的影响研究

为了研究限饲对肉鸡抗氧化水平的影响,试验将哈博德父母代肉鸡分为自由采食组和能量限制组,按要求饲喂不同日粮,测定其抗氧化水平。结果表明:限饲显著降低了肉鸡死亡率(P<0.05);显著提高了肉鸡血清超氧化物歧化酶(SOD)活力(P<0.05),极显著降低了血清中的丙二醛(MDA)含量(P<0.01),对机体内钙含量的影响不显著(P>0.05)。     

Effects of early feed restriction and cold temperature on lipid peroxidation, pulmonary vascular remodelling and ascites morbidity in broilers under normal and cold temperature

Two experiments were conducted to evaluate the effects of early feed restriction on lipid peroxidation, pulmonary vascular remodelling and ascites incidence in broilers under normal and low ambient temperature. In experiment 1, the restricted birds were fed 8h per day either from 7 to 14 d or from 7 to 21 d, while the controlled birds were fed ad libitum. In experiment 2, the restricted birds were fed 80 or 60% of the previous 24-h feed consumption of full-fed controls for 7 d from 7 to 14 d. On d 14, half of the birds in each treatment both in experiment 1 and experiment 2 were exposed to low ambient temperature to induce ascites. Body weight and feed conversion ratio were measured weekly. The incidences of ascites and other disease were recorded to determine ascites morbidity and total mortality. Blood samples were taken on d 14, 21, 28, 35 and 42 to measure the plasma malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). On d 42, samples were taken to determine the right/total ventricular weight ratio (RV/TV), vessel wall area/vessel total area ratio (WA/TA) and mean media thickness in pulmonary arterioles (mMTPA). Low-temperature treatment increased plasma MDA concentration. When broilers were exposed to a cool environment for 3 weeks, plasma SOD and GSH-Px activity were decreased compared with normal-temperature chicks. RV/TV, WA/TA and mMTPA on d 42 were increased in birds exposed to cold, consistent with the increased pulmonary hypertension and ascites morbidity. Early feed restriction markedly decreased plasma MDA concentration. The plasma SOD and GSH-Px activity of feed-restricted birds were markedly higher than those fed ad libitum on d 35 and d 42. All early feed restriction treatments reduced ascites morbidity and total mortality. On d 42, the RV/TV, WA/TA and mMTPA of feed-restricted broilers were lower than that of the ad libitum-fed broilers. The results suggested that early feed restriction alleviated the lipid peroxidation, promoted the activity of enzymatic antioxidant and inhibited pulmonary vascular remodelling. These changes might be associated with reduced ascites incidence.     

早期数量限饲对肉仔鸡生长性能和胴体特性的影响

试验研究了早期数量限饲对肉仔鸡生长性能和胴体品质的影响。200只8日龄艾维茵肉仔鸡被随机分成4组,每组五个重复,每重复10只鸡。对照组基础饲粮根据NRC营养水平配制,试验组肉仔鸡从8日龄开始喂料量分别为对照组的90%、80%和70%,限饲1周后各组恢复自由采食。试验结果表明:在第2周,限饲各组肉仔鸡的体重和日增重分别显著低于对照组(P<0.05);在第3周,限饲90%组完成补偿生长,体重与对照组差异不显著(P>0.05);在第4周,限饲80%和70%组完成补偿生长,体重与对照组差异不显著(P>0.05);5、6、7周及2～7周各组在体重、日增重、日采食量和饲料转化率等方面都无显著差异(P>0.05)。早期数量限饲对肉仔鸡胴体特性没有显著影响(P>0.05)。     

Exogenous leptin advances puberty in domestic hen

The present study was undertaken to examine the effect of recombinant chicken leptin administered to fed ad libitum and feed-restricted immature chickens of a layer strain on ovarian development and the timing of sexual maturity. In the first experiment 11-week-old pullets (77 days of age) fed ad libitum were injected daily with leptin at four dose levels (4, 16, 64 and 256 microg/kg body weight) until sexual maturity (lay of the first egg). Leptin treatment at the highest dose significantly (P<0.05) advanced the onset of puberty (day 116.3+/-1.0) in comparison to controls (day 121.3+/-1.2). The rises of luteinizing hormone, estradiol and progesterone in blood plasma were also advanced by leptin treatment. In the second experiment, both full-fed and feed-restricted pullets (79 days of age) were injected daily with leptin (256 microg/kg body weight). In birds fed ad libitum, exogenous leptin again significantly (P<0.05) advanced first ovipostion (day 118.4+/-1.4 versus day 124.4+/-1.7), while abolishing the significant (P<0.05) delay caused by feed restriction (day 131.5+/-1.6) and restoring the normal onset of sexual maturity (day 125.7+/-1.6). Analysis of the ovaries in 106-day-old pullets revealed that leptin injections advanced follicular development, particularly in birds fed ad libitum, and significantly (P<0.01) reduced follicular apoptosis both in full-fed and feed-restricted birds. In conclusion, we have shown that in female chickens exogenous leptin advances the onset of puberty by attenuation of ovarian apoptosis and enhancement of folliculogenesis.     

Effects of Early Feed Restriction on Performance and Ascites Development in Broiler Chickens Subsequently Raised at Low Ambient Temperature

The objective of this study was to examine the effectiveness of early-age growth limitation, achieved through feed restriction (FR), as a means of reducing ascites mortality in broiler chickens exposed to low ambient temperatures. Feed restriction was applied to broilers from 5 to 11 d of age so as to reduce their weight gain to about 40% of that of control broilers that were fed ad libitum (AL). At the age of 21 d the chickens were exposed to a temperature of 15°C, which induced ascites. By 46 d of age, ascites incidence and mortality in the feed-restricted birds were reduced to 15.79 vs. 36.84% and 7.89 vs. 26.32%, respectively, compared with those in the controls (P < 0.05). After feed restriction was stopped, the FR chickens had accelerated weight gain and improved feed conversion ratio from 11 to 18 d of age (P < 0.05), and by 46 d they had achieved the same body weight as the AL birds. Ascitic broilers had smaller relative breast muscle and spleen weights than those of the healthy broilers at 46 d (P < 0.05). However, the relative weights of lung, heart, and liver and the right ventricle weight per total ventricle weight (RV:TV) ratios were greater in ascitic broilers (P < 0.05). At age 37 d, when ascites had developed but not yet caused mortality, the ascitic broilers had lower plasma concentrations of the thyroid hormones thyroxine and triiodothyronine, and higher hematocrit values (P < 0.05) in comparison with the healthy ones. Ascitic birds also had lower oxygen consumption at 6 wk (P < 0.05), which agrees with information that the terminal stage of the ascites syndrome can be characterized by low oxygen consumption. We concluded that the early-age feed restriction reduced ascites incidence and mortality and prevented reduction of the thyroid hormone concentrations in male broilers reared at low ambient temperature from the age of 3 wk onward.     

Welfare assessment of modified rearing programmes for broiler breeders

1. Female broiler breeders were fed ad libitum or a restricted quantity of food to achieve either a recommended body weight curve or a modified (linear) growth curve that allowed more generous feeding between 6 and 15 weeks of age. The birds were fed a ration containing either a normal or low concentration of crude protein. The welfare of the birds was assessed using a profile of indices of welfare at 6, 12, 18 and 24 weeks of age. 2. The low-protein ration decreased the body weight of birds fed ad libitum and restricted birds were fed substantially more of the low-protein ration to meet target body weights from 3 to 14 weeks of age. 3. The modified restricted rearing programme did not have an effect on indices of welfare. 4. Water intakes and plasma corticosterone concentrations were lower in restricted birds fed the low-protein ration and they spent more time resting, and less time spot-pecking, than birds fed the high-protein ration. 5. Birds fed ad libitum on both rations spent more time resting and less time foraging, drinking and spot-pecking than food restricted birds and were more fearful than restricted birds at 6, 12 and 18 weeks of age. 6. The heterophil:lymphocyte ratio in restricted birds was higher at 6 weeks and lower at 24 weeks compared with birds fed ad libitum. Humoral immunity was lower at 6 weeks of age in birds fed ad libitum and was similar at other ages. Cell-mediated immunity was similar among all treatments. 7. Plasma corticosterone concentrations were higher in restricted birds compared with birds fed ad libitum. Plasma creatine kinase activity was higher in birds fed ad libitum at 6, 12 and 18 weeks of age. Alkaline phosphatase and lactate dehydrogenase activity were higher whereas AST was lower in restricted birds compared with those fed ad libitum. 8. There was no evidence to support the use of low protein rations or linear growth curves to improve welfare in restricted broiler breeder females.     

Effects of early feed restriction on live performance,carcass characteristics,meat and liver composition,some blood parameters,heterophil-lymphocyte ratio,antibody production and tonic immobility duration

The aim of this study was to determine the effects of early feed restriction on performance, carcass characteristics, meat and liver composition, some blood parameters, H-L ratio, antibody titers against SRBC and tonic immobility duration in broilers. One hundred ninety male chicks (Ross 308) were randomly allocated into two treatment groups each of 95 chicks. Broilers in one treatment fed ad libitum until 42 day of age, however in other treatment, broilers were deprived of feed for 4 h per day from 7 to 21 day. Body weight, feed consumption, feed to gain ratio, carcass characteristics and the percentage of examined organs except heart were not statistically significant in groups. Percentage of heart was higher (p < 0.05) in broilers fed ad libitum. At 41 d of age, H-L ratio (p < 0.05) and TI duration (p = 0.001) were higher, serum glucose (p < 0.05) and triglyceride (p < 0.001) levels were lower in broilers fed ad libitum. Chemical composition of breast and thigh and also fat and ash of liver were not affected by early feed restriction. Moisture of liver (p = 0.001) was lower and protein of liver (p < 0.01) was higher in broilers fed ad libitum     

Progressive bradycardia,a possible factor in the pathogenesis of ascites in fast growing broiler chickens raised at low altitude

1. The first objective was to evaluate baseline heart rate (HR) responses in fast growing broilers fed ad libitum from 1 to 45d or subjected to a food restriction (85%, 70% and 55% of ad libitum from 7 to 21d) and a refeeding (22 to 45d) regimen in a normal thermal environment. The second was to evaluate HR and haematocrit responses in fast growing broilers reared at a low environmental temperature and fed ad libitum (A-L) from 1 to 42d, subjected to food restriction (70% ad libitum ) between 7 to 21d and refed thereafter (R-R), or subjected to food restriction between 7 to 42d (R), and to follow the changes in normal birds and those prone to ascites. 2. The baseline HR in the normal thermal environment at 21 and 45d in birds fed ad libitum was lower (P < 0.001) than at 7d. The food-restricted groups had higher HRs at 21d than at 7d, with the differences significant (P < 0.01) for the 70% and 55% treatments. At 21d the HRs in restricted groups were significantly higher (P < 0.01) than in ad libitum -fed birds. After returning to ad libitum feeding the HRs in these birds tended to decline, with the differences significant (P < 0.05) for the 70% and 55% treatments. 3. In the birds exposed to cold, each feeding regimen produced distinct patterns of change in HR and haematocrit. Both feeding regimen and age had significant (P < 0.001) effects on the changes of both variables. Relative to 7d, on 14d and 21d the HRs decreased and haematocrits increased in all groups, but the rates of change were highest in the A-L and R-R birds. The first fulminant cases of ascites were observed during the third week in the A-L group and during the fourth week in the R-R group. None of the chickens from the R group developed ascites. Altogether, the incidence of ascites was 48% in the A-L group and 28% in the R-R group. 4. Among the birds exposed to cold, the ascitic birds had significantly (P < 0.001) lower HRs and higher haematocrits than normal birds from the same feeding regimen group. The time trends in the rates of change in HR and haematocrit were distinctly different (P < 0.001) for ascitic and normal birds. The change in feeding regimen from restricted to ad libitum in the R-R group resulted in a significant (P < 0.001) decrease in HR and increase in haematocrit. 5. In view of the evidence presented, it appears that hypoxaemia and tissue hypoxia in broiler chickens may be a result of circulatory insufficiency associated with progressive bradycardia rather than, as commonly believed, pulmonary insufficiency. In this situation the pulmonary hypertension may be a secondary symptom.     

Plasma oestrogen and triglyceride concentrations and reproductive characteristics of broiler chickens after ten generations of selection at seven weeks of age for high or low plasma very low density lipoprotein concentration.

1. Day old female chicks from two lines of broilers, selected for high or low plasma concentrations of very low density lipoproteins, were fed ad libitum or restricted until point of lay. All birds were fed ad libitum after laying an egg, and aspects of growth and reproduction were measured to 40 weeks of age. 2. Compared with lean line birds the growth rate of fat line females fed ad libitum declined from 16 weeks of age. 3. Mortality from apparently stress-related causes in ad libitum fed fat line females increased from 16 weeks of age and was 71% overall, compared with 26% in ad libitum fed lean line females. Mortality in the corresponding restricted birds was 20% and 7%, respectively. 4. Few fat line females fed ad libitum commenced lay and those which were restricted during rearing stopped laying after the initiation of ad libitum feeding. Egg productions in lean line birds fed ad libitum or restricted were similar. 5. Fat line females fed ad libitum had few yellow follicles and a high rate of atresia at first egg and between 37 and 39 weeks, as did restricted fat line birds between 37 and 39 weeks of age after being fed ad libitum. 6. Plasma concentrations of oestradiol-17 beta were 5-fold higher in fat compared with lean line females at 35 weeks of age. There was a similar large difference in concentrations of plasma triglyceride which reached 59 mg/ml in fat line females fed ad libitum.