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%。     

奶牛低血钙早期预警指标的确立与评估

为了早期预测奶牛分娩时发生低血钙症的可能性,本试验在黑龙江省A和B两个集约化牛场(均有250多头泌乳牛)随机选取产前15~2d和分娩当天奶牛作为实验动物。通过检测试验奶牛分娩当天组血浆钙浓度,明确分娩奶牛低血钙症发病率;通过检测试验奶牛产前和分娩当天血浆中镁离子(Mg2+)、钾离子(K+)和无机磷(P3+)的浓度,阐明奶牛产前血浆中各离子水平与低血钙症的关系,对产后低血钙症发生风险起到预警作用。结果显示:产后低血钙症在牧场A的发病率为90.32%,在牧场B为86.67%;两牧场产前奶牛与分娩当天奶牛的血浆P3+、K+、Mg2+差异极显著,血浆P3+、Mg2+水平与血钙水平呈显著的正相关,血浆K+水平与血钙水平并没有显著的相关性。根据受试牛工作特征曲线(ROC)分析确定了牧场A产前预警值为血浆Ca2+2.11mmol/L,敏感度为100%,特异度为88.2%;血浆P3+1.83 mmol/L,敏感度为75.0%,特异度为82.4%。牧场B产前预警值为血浆Ca2+2.12mmol/L,敏感度为98.7%,特异度为88.5%;血浆P3+1.90 mmol/L,敏感度为98.7%,特异度为65.4%。结论:奶牛产前血浆Ca2+和P3+浓度超过预警值可作为奶牛产后低血钙发生的早期风险预测依据。     

奶牛亚临床低血钙症的蛋白质组学分析

根据奶牛血浆钙浓度将奶牛分为试验组和对照组,并设置2个平行试验组。应用iTRAQ/LC-MS/MS技术对2组奶牛样品进行差异表达蛋白的筛选和鉴定,并结合生物信息学软件对试验结果进行分析。试验共得到398个差异表达蛋白,其中2个平行试验组重叠的蛋白为265个,经过筛选共得到14种具有统计学差异的表达蛋白。结合生物信息学分析中的基因功能分析,结果得到74个注释结果,细胞组成、分子功能和生物过程分别为6,12,55个。根据结果分析可知,奶牛亚临床低血钙症生理和病理现象能够从3个方面解释其生理和病理现象,分别是血钙调节、免疫与炎症反应和血液凝固与补体途径。本试验首次应用iTRAQ结合LC-MS/MS技术对亚临床低血钙症奶牛进行蛋白质组学分析,填补该技术对亚临床低血钙症的空白,并提供科学依据。     

奶牛腐蹄病早期预警指标的确立与评估

为了早期预测奶牛腐蹄病的发生,在黑龙江某集约化牛场开展奶牛腐蹄病流行病学调查,检测患腐蹄病奶牛和健康奶牛血浆中的微量元素及维生素(Cu、Fe、Zn、VE、VH)、矿物质元素(Na、K、Ca、Mg、P)以及氧化应激指标(SOD、MDA、GSH-Px),阐明奶牛血浆微量元素及维生素、矿物质元素和氧化应激指标与腐蹄病的关系以及对腐蹄病发生风险的预警作用。结果表明:腐蹄病奶牛血浆Na、Mg、Zn、VE、VH、SOD和GSH-Px含量极显著降低(P0.01),血浆K、Cu和MDA含量极显著升高(P0.01)。Na、Mg、Zn、VE、SOD和GSH水平与奶牛腐蹄病呈显著正相关;血浆K、Cu、VH和MDA水平与腐蹄病发生呈显著负相关。根据受试者工作特征曲线(ROC)分析确定了该牛场的预警值为血浆Na149.030 mmol/L、K4.345 mmol/L、VE14.390 mg/L、GSH100.365 U/mL。结果显示,奶牛血浆Na、K、VE和GSH指标超过预警值可作为奶牛发生腐蹄病的早期风险预测依据。     

Response of dairy cows to protein level in early lactation

The comparison of cows' protein requirements with the supply of microbial and feed proteins digestible in the intestine shows a large deficit for the first weeks just after calving. The magnitude and duration of the deficit is reflected in the blood parameters of the protein status (protein, urea and free amino acid contents and composition) and of the energy status (glucose, free fatty acid content). Great increases in milk production are noted in this period by meeting protein requirements at all times during the first eight weeks after calving. Sometimes they are achieved at the expense of body stores, but in other cases they can be related to an increase in the efficiency of microbial digestion in the rumen, in the ingestibility of the feeds, or in the intake capacity of the cows. The effects on milk protein synthesis and on the intake capacity of the cows seem to be due to the supply of some essential amino acids, particularly methionine, but also to the supply of non-essential glucose precursor amino acids. More studies are needed on the mechanisms involved, on the long-term effects, and on the secondary effects on reproduction and health.     

Comparison of commercial ELISA blood tests for early pregnancy detection in dairy cows

The objective of the present study was to compare two commercially available blood-based pregnancy tests, namely BioPRYN, an ELISA for pregnancy-specific protein B (PSPB), and an ELISA for pregnancy-associated glycoprotein (PAG), for early pregnancy diagnosis in dairy cattle using transrectal ultrasonography as a gold standard. Transrectal ultrasonography was conducted 26-58 days after artificial insemination (AI) in 197 cattle from 19 farms. Concurrently, a blood sample was collected for determination of serum PSPB and PAG. Transrectal palpation was performed approximately 120 days after AI to verify that pregnancy was maintained. For PSPB and PAG, there were no significant differences (P>0.05) in sensitivity (98.0 and 97.8%), specificity (97.1 and 91.2%), positive predictive values (99.3 and 97.8%), negative predictive values (91.9 and 91.2%) and accuracy (97.8 and 96.4%). In conclusion, the two blood pregnancy assays were equally efficacious and were highly accurate (based on transrectal ultrasonography as the gold standard).     

Endometrial biopsy in Holstein-Friesian dairy cows. III. Bacteriological analysis and correlations with histological findings.

This study examines the results of bacterial culture from 159 endometrial biopsy samples from 97 commercial dairy cows and correlations between bacteriological and histological findings. Bacteria were isolated from approximately 80% of biopsies taken at day 26 and day 40 postpartum. Eleven percent of biopsies were positive for both aerobic and anaerobic culture. Streptococci, Escherichia coli and Actinomyces pyogenes were the most common isolates. Isolation of A. pyogenes from a biopsy at day 26 was positively correlated with isolation of anaerobic bacteria and segmented cell inflammation in the same biopsy, and with subsequent isolation of A. pyogenes at day 40. There was a strong association between isolation of A. pyogenes and anaerobes at day 26 with increased uterine lesions at day 40. Isolation of alpha hemolytic streptococci (AHS) was negatively correlated with isolation of A. pyogenes and with inflammation. Actinomyces pyogenes and AHS showed opposite associations with mononuclear cell inflammation and lymphocytic foci.     

奶牛维生素E缺乏症的血液病理学及其预警

近年来高产奶牛围产期维生素E(VE)缺乏较为普遍,但这一问题在牛场最易被忽视.为此,本试验在某一大型集约化牛场,选取VE缺乏组奶牛40头,健康组奶牛40头,对试验奶牛的抗氧化、肝功、能量代谢、矿物元素和其他维生素指标进行显著性分析、Pearson相关性分析和回归分析及ROC分析.结果显示:与健康组相比,VE缺乏组血浆中...     

Liver function of dairy cows in late pregnancy and early lactation

The possibility that alterations in liver function may occur during late pregnancy as well as after calving has been investigated in healthy dairy cows and the results compared with those from non-pregnant non-lactating cows. There were significant alterations in plasma total bilirubin, glucose, total ketone body and urea concentrations, in bromsulphthalein clearance and in plasma aspartate aminotransferase and creatine kinase activities in periparturient cows compared with non-pregnant non-lactating cows. Of these, only the alterations in glucose, ketone bodies and urea concentrations and bromsulphthalein half-time and retention were markedly different before calving. The degree of fatty infiltration of the liver was significant two weeks before as well as two weeks after calving which differed from previous reports. It seems likely that the changes in the liver in dairy cows are functional and reversible and related to the metabolic demands of late pregnancy and early lactation. The results suggest that such changes in the liver occur well before calving.     

Progesterone concentration in defatted milk of dairy cows in early pregnancy.

Progesterone concentrations have been measured in defatted milk of British Friesian cows of four herds during the oestrus cycles (other than short cycles) immediately before artificial insemination (AI) at oestrus and immediately after AI (in non-pregnant cows), and during early pregnancy. Differences in mean progesterone concentrations between herds were significant (P less than 0.05) on all days within the day 10-18 period after AI, both in pregnant and in non-pregnant, inseminated cows but were not significant between pregnant and non-pregnant cows within herds until day 17 or 18. It is concluded that up to this time (that of luteolysis in non-pregnant cows) undefined factors, variable among herds, can have a much greater influence on the rate of progesterone secretion by corpora lutea and consequent progesterone concentration in plasma and milk than does the presence of conceptuses. Maximum mean progesterone concentration reached during early pregnancy in two herds did not differ significantly; it was reached in the 11-15-day period in one herd but not until 46-50 days in the second. Mean progesterone concentration declined after day 90.     

Oxidative status during late pregnancy and early lactation in dairy cows

In the last few years, the detection of free radical damage and the body's defences against it have become increasingly important in clinical medicine as a complementary tool in the evaluation of metabolic status. The aim of this study was to evaluate, under field conditions, the anti-oxidant status of healthy cows during late pregnancy and lactation onset using two parameters: (1) plasma levels of malondialdehyde (MDA), a degradation product of lipid peroxidation, and (2) total antioxidant status (TAS). Results were compared with those obtained in another group of cows with lesser metabolic demands. We also investigated possible relationships between antioxidant status markers and other relevant blood parameters. Our results confirmed the characteristic metabolic changes associated with late pregnancy and early lactation. MDA and TAS provided an accurate reflection of the internal physiological status of the animal. The data indicated increased lipid peroxidation around parturition, but with wide individual variations that may be attributable not only to the physiological stage but also to unknown factors that will have to be further considered in future studies.     

进口澳大利亚奶牛附红细胞体的发现与诊断

在对从澳大利亚进口的奶牛进行入境隔离检疫时，发现了牛附红细胞体病，感染率100％（1363／1363），其中：体况较肥的牛血液中30％－50％的红细胞感染附红细胞体，瘦弱牛，极度消瘦的牛血液中60％－80％以上的红细胞感染附红细胞体，使用贝尼尔3．5毫克／千克体重治疗效果较好，在广西是首次从澳大利亚进口的奶牛中发现附红细胞体病。