Prevalence of subclinical ketosis in dairy cattle in the Southwestern Iran and detection of cutoff point for NEFA and glucose concentrations for diagnosis of subclinical ketosis

Subclinical ketosis (SCK) is simply a condition marked by increased levels of circulating ketone bodies without the presence of the clinical signs of ketosis. Subclinical ketosis can cause economic losses through decreased milk production and association with preparturient diseases. Limited information is available regarding the prevalence of SCK in dairy herds in Southwestern Iran. The objectives of this study were (i) determination of the cutoff point of nonesterified fatty acids (NEFAs) and glucose concentrations for diagnosis of SCK using receiver operating characteristic (ROC) analysis, and (ii) determination of prevalence of subclinical ketosis in apparently healthy dairy cattle in Southwestern Iran. From October to December 2009, a total of 100 clinically healthy multiparous Holstein cows (3-8 years old) were randomly selected from 16 dairy herds around Kazerun, Fars Province, Iran. The cows had two-six lactations, with body weight ranging from 500 to 650 kg. Blood samples for each cow were taken at 2, 4 and 6 weeks post parturition and 3-4h after the morning feeding. The optimal cutoff point was set, by the ROC method, to >0.26 mmol/L for NEFA, and < 2.26 mmol/L for glucose with corresponding 82.54% sensitivity and 91.89% specificity for NEFA and 44.44% sensitivity and 78.38% specificity for glucose. Cows with BHB concentrations higher than 1200 μmol/L were classified as having SCK. In 2, 4 and 6 weeks post parturition 63%, 68% and 59% of the tested cows were subclinically ketotic. Overall, 97% of tested cows (97/100) were considered subclinically ketotic in at least one sample period. Thirty percent of tested cows (30/100) suffered from subclinical ketosis in all of the 2, 4 and 6 weeks postpartum. The results suggest that, a cut-off point of 0.26 mmol/L for NEFA concentrations can be used during early lactation for diagnosis of subclinical ketosis and making management decisions for prevention and treatment. Glucose cannot be a good criterion for diagnosis of SCK and it does not appear to be useful for monitoring subclinical ketosis.     

奶牛酮病研究

酮病是高产奶牛常见的代谢性疾病。随着奶牛生产水平的提高，酮病发生率也逐年升高。本文从酮病的发生机制、症状，与其他围产期疾病的关系、病理变化和防治等方面进行了综述。     

新疆昌吉州围产期奶牛酮病流行病学调查及其对生产性能影响

为了掌握新疆昌吉州围产期奶牛酮病的流行现状,研究该病对奶牛生产性能的影响,采集昌吉州1 898 份围产期奶牛血液进行血酮检测,统计分析酮病和亚临床酮病的发生率,比较健康奶牛、亚临床酮病奶牛、酮病奶牛在产奶量、乳品质、免疫力指标方面的差异。结果昌吉州围产期奶牛酮病、亚临床酮病发生率分别为10.06%和33.09%;酮病奶牛、亚临床酮病奶牛与健康奶牛相比,平均日产奶量分别降低14.39%（P<0.05）、5.26%（P<0.05）,乳脂率分别降低11.99%（P<0.05）、6.0%（P<0.05）,乳糖率分别降低6.14%（P<0.05）、2.18%（P>0.05）,乳蛋白率分别降低11.88%（P<0.05）、5.80%（P<0.05）,体细胞数分别提高26.72%（P<0.05）、16.29%（P<0.05）,IgA含量分别降低23.81%（P<0.05）、9.52%（P>0.05）,IgG含量分别降低15.71%（P<0.05）、7.33%（P<0.05）,IgM含量分别降低14.58%（P<0.05）、6.25%（P<0.05）。结论昌吉州围产期奶牛均存在酮病和亚临床酮病的发生,并能够使奶牛的产奶量、乳品质和免疫力降低。     

亚临床酮病对奶牛产后子宫恢复状况和血液白细胞的影响

根据胎次、年龄、产奶量、分娩日期分别筛选出亚临床酮病奶牛、非酮病奶牛各22头作为试验组、对照组奶牛;于分娩后第15天,使用兽用B型超声诊断仪对试验奶牛进行子宫颈、子宫角直径的测量,并采集血样进行白细胞分类计数.于分娩后第40天,对试验奶牛进行子宫颈黏液采样、涂片、染色,镜检多形核白细胞的浸润情况.结果显示,与对照组相比,分娩后15d试验组奶牛的子宫颈直径要显著增大(P＜0.05),白细胞总数(WBC)、淋巴细胞数量(LYM)和中性粒细胞数量(NEU)显著降低(P＜0.05).分娩后40 d时,试验组奶牛子宫颈黏液中各评定等级下的多形核白细胞(PMN)浸润率均较对照组奶牛高,两组间差异不显著(P＞0.05).试验表明,亚临床酮病奶牛的子宫复旧出现了一定程度的推迟,子宫更容易出现炎症反应.     

奶牛临床和亚临床酮病的血浆代谢组学研究

【目的】基于代谢组学的气相色谱(GC)/质谱(MS)联用技术分析临床酮病、亚临床酮病和健康的奶牛血浆代谢谱,观察奶牛体内代谢产物的变化,寻找内源性代谢分子标记物,用于发现奶牛临床和亚临床酮病的早期诊断及病情进展的特征生物标志物,并阐明该病发病机制。【方法】收集临床酮病奶牛血样24例,亚临床酮病奶牛33例,健康对照组奶牛23例,静脉采集试验奶牛血液,分离血浆,检测其β-羟丁酸、血糖等生化指标。将血浆样品预处理后,运用GC/MS联用技术检测各组奶牛血浆代谢产物,利用质谱数据库对其进行鉴定。采用主成分分析（principal component analysis, PCA）和偏最小二乘判别分析法（partial least squares discriminant analysis, PLS-DA）等多元统计方法对临床酮病组、亚临床酮病组和健康对照组奶牛检测数据进行模式识别分析。通过PLS-DA方法建立疾病诊断模型后,筛选潜在的疾病生物标记物。【结果】 以80例奶牛血浆样品为分析对象,研究建立了内源性代谢物谱的GC/MS分析方法,并利用NIST（2008）商业质谱数据库对检测到的代谢物进行快速鉴定,共检测出267个变量。将代谢组数据导入SIMCA-P软件进行主成分分析和偏最小二乘法判别分析,代谢组数据可将患病组与健康组分别聚类区分,并且寻找到组间种类无差别代谢物为40种。结果显示与对照组相比,临床和亚临床酮病的差异代谢物均为32个,临床酮病与亚临床酮病组相比有13个差异代谢物。通过查找KEGG数据库,对代谢物进行分析,这些代谢物主要与氨基酸代谢、脂肪代谢和碳水化合物代谢等能量代谢途径相关。【结论】基于代谢组学的GC/MS技术对酮病奶牛血浆进行检测,并结合多元统计分析,共在临床、亚临床酮病和健康组之间发现40种代谢物（主要为脂肪酸,氨基酸和碳水化合物等物质）。证明奶牛血浆样品的GC/MS代谢谱可以有效地对临床酮病组、亚临床酮病组与健康对照组进行区分。该结果也进一步证明了利用代谢组学技术,在一定程度上可以揭示奶牛临床和亚临床酮病的发生和发展变化,而这些对组间分类有贡献的差异代谢物可能是奶牛酮病诊断的潜在代谢标记物和客观指标。通过研究可以发现奶牛临床和亚临床酮病的发生和发展过程中,其血浆内的部分代谢物的代谢模式和代谢途径发生了改变。此外,新的潜在的代谢物也为奶牛酮病的诊断和预防提供了一定的新思路。     

奶牛隐性乳房炎诊断新指标研究进展

乳房炎是造成奶牛业损失最严重的传染性疾病。目前应用于奶牛隐性乳房炎诊断的常用方法有加州乳房炎试验(CMT),乳汁体细胞计数(SCC)等,但在常规使用中都存在一定的局限性。奶牛乳汁中一些酶活性和急性期蛋白量的变化是监测隐性乳房炎很有价值的指标,可用于泌乳早期感染乳区的检测和选择感染奶牛进行干乳期治疗。结合珠蛋白(HP)和血清淀粉样蛋白A(SAA)是奶牛最为敏感的急性期蛋白,它们在急性炎症时大量增加。概述了乳酸脱氢酶(LDH)、N-乙酰基--βD-氨基葡萄糖苷酶(NAGase)、乳过氧化物酶(LP)、碱性磷酸酶(ALP)、结合珠蛋白(HP)和血清淀粉样蛋白A(SAA)等指标在奶牛乳房炎诊断中的应用研究进展。     

隐性乳房炎奶牛4个微卫星座位的遗传变异分 析

选择牛23号染色体上4个微卫星标记BM1818、BM1443、BM1258 和BM1905,用非变性聚丙酰胺凝胶电泳方法对石河子某奶牛场150头进口荷斯坦奶牛进行了遗传变异的检测分析并计算相应的遗传指标,利用SPSS12.0 软件分析了四个微卫星座位与进口荷斯坦牛隐性乳房炎的关系,探讨各自座位上不同基因型与奶牛隐性乳房炎之间的相互关系。     

Study on some risk factors and effects of bovine ketosis on dairy cows from the Galicia region (Spain)

The study was designed to determine the relation between β‐hydroxybutyrate (BHB) concentrations in milk from dairy cows after calving and the length of the previous lactation, the dry period and the 305‐day normalized production, and to assess the influence of BHB concentrations on culling and test‐day milk productions and somatic cell counts (SCC) throughout the lactation that followed the BHB measurement. The data used in the study were obtained from 59 187 cows in the Galicia region (Spain). BHB determination was performed using Fourier‐transformed infrared spectrometry from the milk samples collected from each cow on the first post‐partum test day. For statistical analysis, the following methods were applied: (i) ordinal regression to assess the effect of the length of the previous lactation, the dry period and the 305‐day normalized milk production on milk BHB, (ii) a Cox model to estimate the influence of the BHB concentration on risk of culling (overall and for a variety of reasons) and (iii) linear regression to assess the link between BHB and the milk yield and SCC obtained from each of the tests day performed throughout lactation. The probability of having higher BHB concentrations increased when the length of the previous lactation (p = 0.006), the dry period (p = 0.003) and the 305‐day normalized milk yield (p = 0.005) increased. However, the slight increase observed (especially for the case of the dry period and the 305‐day milk yield) would not justify that measures be implemented to reduce these traits. Higher concentrations of BHB led to an increased risk of culling due to ‘death’ (p ≤ 0.001) and ‘urgent slaughter’ (p ≤ 0.002) (both causes of involuntary culling). It also led to a reduction in milk production (p < 0.001) and an increase in SCC (p < 0.001) in the post‐partum; from that moment onward (including peak lactation), there were no differences in those two parameters depending on the BHB levels.