【作者】 李军乔；

【导师】 黄仁录；

【作者基本信息】 河北农业大学 ， 动物营养与饲料科学， 2004， 硕士

【摘要】 本研究通过两个试验，以28～50日龄健康AA商品肉用公鸡为试验对象，以有效温度(ET)为指标研究了持续日变高温对肉仔鸡生产性能、血液代谢产物、血清酶活性、胴体品质、肉品感观性状、组织过氧化状态、肝脏HSP72mRNA含量的影响，结果表明热应激降低肉鸡的生产性能，对肉品质有不利影响。 在高温环境对肉仔鸡生产性能、血液代谢产物和肉品质影响的研究中，选择270只28日龄AA肉用公鸡，随机分为3组，每组6个重复，每个重复15只鸡，分别饲养于三个环境控制舱中。采用配对试验设计，3个试验组均采食同一日粮。各组有效温度分别为：持续日变高温组为28.8℃～36.5℃～28.8℃，适温组和适温配对组均为21.2℃；高温组和适温组鸡自由采食，配对组鸡喂给高温组前一天的饲料采食量。于试验后第0、7、14和21天各重复称重，采血测定血清中葡萄糖(Glu)、尿酸(UA)、甘油三脂(TG)、总蛋白(TP)、白蛋白(ALB)、球蛋白(GLOB)含量，试验第21天测定鸡的胴体品质和肉质。试验结果表明：①热应激显著降低肉鸡的采食量和生长速度，降低饲料转化率，而且热应激对肉鸡生长速度和饲料转化率的影响不完全依赖于采食量的下降。与适温组和适温限饲组相比，高温组热暴露三周平均日增重分别降低39.05％(P＜0.01)和14.22％(P＜0.01)，料肉比分别增加25.64％(P＜0.01)和15.29％(P＜0.01)。高温组日均采食量较适温组降低24.24％(P＜0.01)。②热应激显著增加血糖含量，后又降低；随热暴露时间的延长，血清中甘油三脂呈下降趋势，第三周时高温组血清甘油三酯含量较其他两组显著降低(P＜0.05)。三组血清中总蛋白、球蛋白、白蛋白含量均无显著变化(P＞0.05)；与适温组相比，高温组尿酸随热暴露时间的延长而增加，但三周均无显著差异(P＞0.05)，与配对组相比，高温组热暴露三周均显著升高。③同适温组相比，高温组肉鸡有较高的屠宰率(P＜0.05)、全净膛率、半净膛率、腿肌率及腹脂率(P＜0.01)。同配对组相比，高温组有较高的全净膛率(P＜0.05)、半净膛率(P＜0.01)，较高的腿肌率和腹脂率(P＜0.01)，而其他指标则无显著差异(P＞0.05)。④高温环境显著影响鸡肌肉一些感观指标。同适温组相比，高温组胸肌和腿肌L~*值、滴水损失和剪切力显著升高(P＜0.01)，腿肉色a值显著降低(P＜0.01)，胸a值、胸肌和腿肌b值、宰后15分钟及24小时的pH值影响较小，统计学分析差异不显著(P＞0.05)；同配对组比，高温组胸肌和腿肌L~*值、滴水损失和剪切力显著升高(P＜0.01)，其他指标均无显著差异(P＞0.05)。 在高温环境对肉仔鸡血清酶活性、脂质过氧化和肝脏中热应激蛋白(HSP72)转录水平动力学变化影响的研究中，选择270只28日龄AA肉用公鸡，随机分为3组，每组6个重复，每个重复15只鸡，分别饲养于三个环境控制舱中。采用配对试验设计，3个试验组均采食同一日粮。各组有效温度分别为：持续日变高温组为28.8℃～36.5℃～28.8℃，适温自由采食组和适温配对组都为21.2℃。高温组和适温组鸡自由采食，配对组鸡喂给高温组前一天的饲料采食量。于试验第2、5、8、12、15、22天每组6只鸡心脏采血后屠宰，测定肝脏和肌肉中丙二醛(MDA)含量、血清中碱性磷酸酶(AKP)活性、肌酸肌酶(CK)活性、乳酸脱氢酶(LDH)活性和丙二醛含量、肝脏中HSP72mRNA含量。试验结果表明①热应激使得肉鸡血清中肌酸肌酶活性显著升高、碱性磷酸酶活性显著降低(P<0 .01)、乳酸脱氢酶活性先升高后降低。②热应激显著提高肉鸡肝脏(P<0 .01)和血清(P<0 .01)中丙二醛含量，肉中的丙二醛含量统计学分析差异不显著(P> .05)。而且此影响也不依赖于热应激造成的采食量的降低。③高温和限饲均导致肝脏中HSP72mRNA含量升高，在第22天高温组与适温组差异显著(P( 0 .05)。更多还原

【Abstract】 The main objective of this thesis is to study the effects of heat stress on the performance, carcass characteristics, meat visual quality, serum biochemical parameters, MDA concentration of tissues and HSP72mRNA of liver during the age of 28-50 days healthy Arbor Acre(AA) broilers. The results showed that: heat stress decreased the broiler’s performance and had harmful effect to the meat quality.(1) Two hundred and seventy 28-day-old AA broilers were equally divided into 3 groups to study the effect of high temperature on its performance, blood metabolic product. There were 6 replicates in each group and 15 chickens in each replication. Pair test design was adopted to test the effect of ambient temperature on broilers.One group broilers(34AL) were in diurnally high temperature(ET28.8 # -36.5 # -28.8 # ), another group broilers(22AL) fed ad libitum in neutral thermal environment (ET21.2#), the other group broilers(22PF) raised in neutral thermal(ET21.2#) but gave feed consumed by high temperature just before one day. Each replication were weighed at 0, 7, 14, 21 days and collected blood to measure the content of Glu, UA, TG, TP, ALB and GLOB. The carcass character and meat quality were measured at 21-day. The results showed: ?Heat stress decreased broilers’ feed intake, growth rate and feed conversion, while these effect were not independent on the decrease of the feed intake. Compared with the 22AL group and 22PF group, ADG of the high temperature group with 3 weeks decreased 39.05% and 14.22%(P<0.01) respectively, feed conversion increased 25.64% and 15.29% (P<0.01) respectively. Comparing to the neutral group, feed intake of the high temperature decreased 24.24%( P<0.01). (2) High temperature increased the serum Glu content significantly but subsequently decreased it. With the long time under the high temperature, the serum TG had the downward trend. The TG content of the high temperature of 3-week decreased significantly (P<0.05), but the serum TP, ALB and GLOB had no obvious change (P>.05). Compared with 22AL group, the UA content increased with the long time of high temperature, but there had no significant difference during the three weeks. Compared with 22AL but feed limited group, the serum indicator all increased obviously after the three weeks high temperature. (3) It was found that compared to 22AL group, high temperature increased the broiler chicks’ slaughter weight rate, full net carcass rate, semi net carcass rate, leg muscle rate and abdominal fat rate significantly (P<0.01). Compared with the22PF group, the high temperature group had higher full net carcass rate (P<0.05), semi net carcass rate (P<0.01), leg muscle rate and abdominal fat rate (P<0.01), while the other indicator had no significant difference(P>0.05). (4) High temperature had obvious influence on some muscular sensation indicator. Compared with 22 AL group, high ambient temperature enhanced significantly the value of L*, drip loss and shear value of breast and thigh meat (P<0.01), while a value of leg meat decreased significantly (P<0.01), but breast a value, breast and leg b value, the Ph value of 15min and 24h after slaughter were not significant affected (P>0.05). The others indicator had not significant difference.(2) Two hundred and seventy 28-day-old AA broilers were equally divided into 3 groups, 6 replicates in each group and 15 chickens in each replicate to study the effect of high temperature to broilers’ serum enzyme, lipid peroxidation and the active change of HSP72mRNA. Pair test design was adopted to test the effect of ambient temperature on broilers. One group broilers(36AL) were in diurnally high temperature(ET28.8#~36.5# -28.8 #), another group broilers(22AL) fed ad libitum in neutral thermal environment (ET 21.2#), the other group broilers(22PF) raised in neutral thermal(ET21.2#) but gave feed consumed by high temperature just before one day. Each group slaughtered 6 broilers at 2, 5, 8, 12, 15, 22 day, and collected blood to measure the activity of AKP, CK, LDH and the content of MDA. MDA content of the liv更多还原