能量负平衡对泌乳早期奶牛生产性能、繁殖性能和机体代谢的影响

在某一集约化牛场,随机选取年龄、胎次、泌乳量相近的奶牛60头,分别在产后1、14、28、42、56d和70d时颈静脉采血,根据血糖浓度在6个时间点分为能量负平衡组和对照组,同时调查和分析奶牛日粮营养水平(能量、CP、CF、CFb、Ca、P)、生产性能(BW、MY、DMI)、繁殖性能(首次配种间隔、情期受胎率、发情率、配种指数)、血液生化指标(Glu、BHBA、NEFA)和内分泌指标(Ins、Gn、Lp、E2、P4)。结果表明:奶牛泌乳早期存在不同程度的能量负平衡(NEB),产后14d最高。NEB能使奶牛产后血浆E2、P4水平降低,产后DMI、BW和MY均减少。能量负平衡奶牛血浆Ins、Gn和Lp浓度降低,表现低血糖、高血浆NEFA和BHBA生化特性,首次配种间隔延长,情期受胎率和发情率降低,配种指数增高。这些结果提示,奶牛泌乳早期易发能量负平衡,不仅与日粮能量水平低、泌乳量高、干物质摄入少和体重损失有密切关系,而且与机体内分泌未完全协调发挥作用有关。并且能量负平衡会降低奶牛生产性能和繁殖性能。     

血液指标监测奶牛脂肪肝研究进展

脂肪肝是围产期奶牛高发性疾病,可对奶牛养殖业造成巨大经济损失。血液中谷草转氨酶（AST）、葡萄糖（GLU）、非脂化脂肪酸（NEFA）、β-羟丁酸（BHBA）是脂肪肝的常规监测评价指标,然而上述疾病监测指标存在无法实现疾病早期监测预警、对脂肪肝的评价效果不佳等缺点,使得奶牛脂肪肝早期预警诊断难,严重制约了防控方案的实施。研究发现,相关血液生长分化因子对奶牛脂肪肝具有预警效果。文章主要论述近年来血液相关因子与围产期奶牛脂肪肝的关系的相关研究进展,为更好地建立奶牛脂肪肝早期监测技术提供参考。     

围产期奶牛的代谢特点及其营养调控

围产期是奶牛泌乳周期中最为关键的阶段,该阶段奶牛代谢最大的特点是能量摄入减少而需求增加从而导致能量负平衡。探寻缓解围产期奶牛能量负平衡的调控措施是减少奶牛疾病发生率的重要基础。本文对近年来围产期奶牛能量负平衡的营养调控研究进行了归纳和总结,旨在为寻找提高奶牛健康水平和生产性能的途径提供新的思路。     

过瘤胃胆碱对围产期奶牛营养作用的研究进展

本文通过研究围产期奶牛的代谢特点,阐述了胆碱的生物学功能及其在瘤胃中的代谢机理,同时论述了过瘤胃胆碱对围产期奶牛的营养作用。旨在为应用过瘤胃胆碱缓解奶牛能量负平衡,减少围产期奶牛营养代谢病发病率,提高奶牛生产性能,延长奶牛利用年限奠定理论参考依据。     

中草药添加剂对围产期奶牛血液生化指标及生产性能的影响

本研究旨在研究中草药添加剂对围产期奶牛血液生化指标及生产性能的影响。试验选择36头体况、预产期和胎次相近的荷斯坦奶牛,采用完全随机试验设计,分为3组,每组12头奶牛。3组奶牛在基础日粮中分别添加0、150和300 g/d的中草药添加剂,预饲期1周,正饲期6周。奶牛产后每周采集1次饲料样、血样和奶样,测定其干物质采食量、血液生化指标及乳成分等指标。结果表明,随着中草药添加剂饲喂量的增加,围产期奶牛产后产奶量表现出一定的升高趋势,产奶量分别增加5.1%和10.6%,但与对照组相比差异不显著（P>0.05）,围产期奶牛饲喂中草药添加剂对干物质采食量没有显著影响（P>0.05）。与对照组相比,随着中草药添加剂饲喂量的增加,乳中体细胞数显著降低（P<0.05）,分别下降62.7%和76.6%,但对乳中其他常规指标没有显著的影响（P>0.05）。与对照组相比,随着中草药添加剂饲喂量的增加,奶牛血清中非酯化脂肪酸（NEFA）含量显著降低（P<0.05）,降低水平分别为29.0%和35.1%,血清中其他常规指标没有显著变化（P>0.05）。综上所述,在本试验条件下,推荐围产期奶牛中草药添加剂添加量为300 g/d,可以显著降低乳中体细胞数和血中NEFA含量,改善奶牛健康状况,提高奶牛产后生产性能。     

能量平衡对围产期奶牛泌乳和干物质摄入量及机体代谢的影响

为了阐明不同能量平衡状况的围产期奶牛泌乳量、干物质摄入的变化及其机体代谢调节作用。在某一集约化牛场选取胎次、年龄相近的奶牛,分为高血糖组(H)和低血糖组(L),每组各15头。在产前21、14、7d和分娩当天,产后7、14、21d,分别记录奶牛围产期干物质摄入量(DMI)、泌乳量(MY),并测定血浆血糖(Glu)、游离脂肪酸(NEFA)、β-羟丁酸(BHBA)、胰岛素(Ins)、胰高血糖素(Gn)、瘦蛋白(Lp)、皮质醇(Cor)的浓度。结果显示,试验奶牛产后泌乳量和干物质摄入量均增加,但是产后能量负平衡发生率高于产前,产后21d达最高;两组产后血浆Glu水平均降低,血浆NEFA和BHBA升高,L组血浆NEFA和BH-BA水平高于H组(P0.05);H组血浆Ins与Lp水平高于L组(P0.05),血浆Gn与Cor水平低于L组(P0.05)。围产期不同能量平衡状态的奶牛机体能量代谢发生了各自适应性的变化。血浆低水平Ins、Lp和高水平Cor在缓解能量负平衡方面发挥了重要作用。     

围产期饲喂过瘤胃胆碱对奶牛生产性能及血液生化指标的影响

本试验旨在研究围产期奶牛饲喂过瘤胃胆碱(RPC)对泌乳性能、血液生化指标及繁殖性能的影响。试验采用单因素试验设计,选用60头年龄、胎次、预产期、上一胎次产奶量相近的健康围产期奶牛,随机分为3组,每组20头。Ⅰ组饲喂基础日粮,Ⅱ组和Ⅲ组在基础日粮上分别添加25 g/d和50 g/d RPC,饲喂期从产前3周至产后3周,共42 d。结果表明:Ⅱ组产奶量在产后1~8周显著高于Ⅰ组和Ⅲ组(P0.05);在产后第2周,Ⅲ组的乳脂率、乳蛋白率显著高于Ⅰ组(P0.05);在整个试验期,Ⅱ组的谷丙转氨酶含量显著低于Ⅰ组(P0.05),Ⅲ组的天门冬氨酸转氨酶显著含量低于Ⅰ组(P0.05);产后第1周和第2周,Ⅱ组的β-羟丁酸、非酯化脂肪酸含量显著低于Ⅰ组(P0.05);Ⅱ组的甘油三酯含量显著高于Ⅰ组和Ⅲ组(P0.05),Ⅲ组的总胆固醇含量显著高于Ⅰ组(P0.05);日粮中添加RPC可以显著提高情期受胎率(P0.05),显著缩减奶牛空怀天数(P0.05),也对产后初次配种时间的缩短和配种次数的降低有影响。日粮中添加RPC可提高围产期奶牛生产性能,对血液生化指标和繁殖性能产生有利影响,本试验条件下RPC最佳添加剂量为每头牛25 g/d。     

棕榈酸对奶牛生产性能及血液生化指标的影响

选用32头荷斯坦奶牛,按产奶量、胎次、泌乳天数随机配成4组,每组8头,研究棕榈酸对奶牛干物质进食量(DMI)、生产性能及血液生化指标的影响.结果表明:1.5%组、3.0%组及4.5%组DMI比对照组分别下降2.04%、6.12%及10.44%;产奶量呈线性下降趋势,但差异不显著(P＞0.05);添加棕榈酸可提高乳蛋白含量,其中3.0%组及4.5%组乳蛋白率较对照组分别提高4.03(P＜0.05)及3.89%(P＜0.05),对乳脂率和乳总固体率影响差异不显著(P＞0.05);血糖、血钙浓度有下降的趋势,血镁浓度有升高的趋势,但差异均不显著(P＞0.05).     

应用血中生化指标监测围产期奶牛脂肪肝

测定了９头中国荷斯坦奶牛分娩前后血浆中葡萄糖（Ｇｌｕ）、游离脂肪酸（ＦＦＡ）和天门冬氨酸氨基转移酶（ＡＳＴ）的含量，用以监测受试牛脂肪肝的发生和转归。结果表明：在产后１５～２０ｄ内，脂肪肝患牛血糖平均值极显著低于正常牛；在产后２５ｄ内，血浆中ＦＦＡ平均值显著高于正常牛；在产后１０ｄ至２０ｄ间，血浆中ＡＳＴ平均值极显著高于正常牛。受试牛产后脂肪肝的发病率为４４％（４／９），平均发病时间为产后８．８ｄ，病程平均持续１５ｄ。     

不同能量摄入水平对围产期健康奶牛生产性能及脂肪代谢的影响

将健康的30头围产期奶牛随机分为3组，分别于产前28天开始饲喂NRC标准日粮、NRC标准增加20％的日粮和NRG标准减少20％的日粮，产后各组奶牛均饲喂标准日粮，至产后56天结束。观察干奶期不同能量摄入水平对产后奶牛干物质摄入量、泌乳量及脂肪代谢的的影响。试验结果表明：围产期是机体生理状况处于剧烈变化的时期，奶牛产后的脂肪代谢活动较产前明显增强，但健康奶牛均能通过调整糖代谢、脂代谢和蛋白质代谢，促进能量与营养物质间的相互转化，适应机体的各种生理变化。     

胆碱对奶牛肝脏脂肪代谢的调控作用及机制

围产期奶牛脂肪肝等营养代谢性疾病的防治和调控是提高生产性能和效益的关键.胆碱作为一种动物生长发育必需的营养素,在奶牛肝脏脂肪代谢调控方面发挥着重要的作用.饲粮中适当补充胆碱可以有效降低肝脏脂肪含量和预防脂肪肝,并维持肝脏的正常生理功能.胆碱主要通过上调脂肪分解和下调脂肪生成途径的基因和蛋白的表达水平来调节脂肪代谢,从而减少脂肪沉积,缓解脂肪肝.本研究在已有文献报道基础上,阐述了胆碱的特性和功能,围绕胆碱对动物肝脏脂肪代谢的调节作用及机制进行了综述,旨在为奶牛维持机体健康、提高反刍动物生产性能提供理论依据.     

Plasma lipoproteins and fatty liver in dairy cows

Dairy cows were classified on the basis of a histological study after a hepatic biopsy conducted in the second week post partum (mild fatty liver, moderate fatty liver, severe fatty liver). Plasma lipoproteins were separated into various density classes by repeated ultracentrifugation. The results indicate that the beginning of lactation is associated with a low concentration of the 1.006 to 1.063 g ml-1 lipoprotein fraction. The lowest concentrations occurred in cows with severe steatosis or during the evolution of moderate steatosis.     

Haematology of subclinical fatty liver in dairy cows

The relationship between liver fat content and haematology was investigated in 369 cows from eight herds sampled in the second week after calving. High levels of fat in the liver were associated with a depression in total white cell count and in neutrophils, eosinophils and lymphocytes. There was no correlation between liver fat content and the percentage of E rosetting lymphocytes, packed cell volume or haemoglobin concentration. The changes in peripheral white cell counts may be related to the increased incidence of post parturient disease in cows with fatty liver.     

酮病对泌乳早期乳牛体内代谢和内分泌的影响

随机选取某奶牛场10头患临床酮病乳牛和10头同期健康对照组乳牛，检测了2组乳牛血液10项指标，阐明了酮病对泌乳早期乳牛体内代谢和内分泌的影响。结果显示，酮病乳牛血糖浓度极显著降低（P〈O．01），血浆NEFA和BHBA的浓度明显增高（P〈O．01）；酮病乳牛血浆Ins、LP、NPY、E2的浓度和Ins／Gn比值均明显降低（P〈O．05），而血浆Gn浓度未明显升高，P4未明显降低（P〉0．05）。表明，酮病乳牛体内某些激素协调作用紊乱会妨碍酮病乳牛能量负平衡的缓解，并将对产后生殖机能产生不良影响。     

复合酵母培养物对奶牛生产性能的影响

<正>近年来,国内外有很多关于酵母培养物在奶牛生产中应用的研究,在日粮中添加酵母培养物可以稳定瘤胃内环境,促进有益菌群的增殖(张连忠,2009),同时     

泌乳奶牛脂肪肝早期诊断的研究

为了寻找泌乳奶牛脂肪肝早期诊断方法,本研究从某千头奶牛场随机选取了30头乳酮阳性的奶牛,其中临床酮病牛10头,亚临床酮病牛20头,测定其肝脂含量以及血中代谢指标和肝功指标。试验结果表明,脂肪肝的奶牛存在能量负平衡现象,机体呈现高游离脂肪酸血症、高酮血症,肝脂浸润越重,能量代谢障碍越严重;乳酮阳性出现时间的早晚与脂肪肝的严重程度密切相关,乳酮阳性产后出现的越早,乳酮阳性越明显,肝脂浸润越重;随肝脂浸润程度的加重,肝功多个指标会出现异常,重度的脂肪肝会引发肝功能不全。本试验证明,酮粉法可以作为早期诊断奶牛脂肪肝的初选方法,肝功指标异常可作为诊断脂肪肝的辅助方法,两者结合可作为奶牛脂肪肝的实用、有效和准确的早期诊断方法,准确率可达80%。     

Hepatocyte apoptosis in dairy cows with fatty infiltration of the liver

The objective of the present study was to analyse the apoptotic process of liver cells in dairy cows with fatty infiltration of the liver using indicators of DNA damage and immunohistochemistry. For this purpose, sixteen dairy cows with fatty liver were examined. On clinical examination, the physical condition of the animals was fair in nine and poor in seven cows. The most dominant clinical signs were reduced ruminal motility, inappetance and/or anorexia and recumbency. Postmortem examination, in seven cases, revealed enlarged liver (18-33kg), icteric carcasses and distended gallbladder. Laboratory results included neutrophilia, hypochloraemia, decreased concentrations of total bilirubin and increased concentrations of β-hydroxy butyric acid, non-esterified fatty acids and insulin. The activities of aspartate aminotransferase, γ-glutamyl transpeptidase, creatine kinase and lactate dehydrogenase were high. Histopathological examination of hepatic specimen showed lipid drops in cytosol with indistinct cellular membranes. In control hepatic cells, the DNA was tightly compressed and maintained the circular disposition of the normal nucleus. However, in the diseased cows, the damaged DNA migrated from the core toward the anode, forming a tail of a comet. Compared to controls, numerous ssDNA and caspase-3-positive cells were detected in the liver. To the authors' knowledge, this is the first study to document accelerated apoptosis of hepatocytes in dairy cows with fatty infiltration of the liver.     

Hepatocyte apoptosis in dairy cows with fatty infiltration of the liver

The objective of the present study was to analyse the apoptotic process of liver cells in dairy cows with fatty infiltration of the liver using indicators of DNA damage and immunohistochemistry. For this purpose, sixteen dairy cows with fatty liver were examined. On clinical examination, the physical condition of the animals was fair in nine and poor in seven cows. The most dominant clinical signs were reduced ruminal motility, inappetance and/or anorexia and recumbency. Postmortem examination, in seven cases, revealed enlarged liver (18–33 kg), icteric carcasses and distended gallbladder. Laboratory results included neutrophilia, hypochloraemia, decreased concentrations of total bilirubin and increased concentrations of β-hydroxy butyric acid, non-esterified fatty acids and insulin. The activities of aspartate aminotransferase, γ-glutamyl transpeptidase, creatine kinase and lactate dehydrogenase were high. Histopathological examination of hepatic specimen showed lipid drops in cytosol with indistinct cellular membranes. In control hepatic cells, the DNA was tightly compressed and maintained the circular disposition of the normal nucleus. However, in the diseased cows, the damaged DNA migrated from the core toward the anode, forming a tail of a comet. Compared to controls, numerous ssDNA and caspase-3-positive cells were detected in the liver. To the authors’ knowledge, this is the first study to document accelerated apoptosis of hepatocytes in dairy cows with fatty infiltration of the liver.     

酮病奶牛肝脏脂肪酸代谢研究进展

酮病奶牛机体处于能量负平衡状态,脂肪组织大量动员,产生大量的非酯化脂肪酸(NE-FA)进入血液。而肝脏作为机体脂类代谢的主要器官,脂肪酸氧化代谢状态直接影响酮体和甘油三酯的生成,是控制酮病和脂肪肝等营养代谢性疾病发生的关键代谢途径。文中综述了酮病奶牛肝脏脂肪酸的摄入、代谢及其与酮病发生发展之间的关系。     

Reduced fertility associated with fatty liver in high-yielding dairy cows

In a group of 20 high-yielding dairy cows, 10 with mild and 10 with severe fatty liver one week after calving, there was an association between fatty liver and reduced fertility. The 10 cows with severe fatty liver had a significantly longer calving interval to the next lactation compared to the cows with mild fatty liver. In addition there was a significant positive correlation between the amount of fat in the liver and calving interval. The results support the concept that liver dysfunction at calving adversely affects subsequent fertility.