乳酮症试纸条对奶牛酮病检测的使用效果评价分析

本文通过随机选择40头奶牛,采用乳酮症试纸条和尿酮症试纸条分别对酮病的诊断效果进行比较研究。结果表明,乳酮症试纸条与尿酮症试纸条对奶牛酮病的诊断效果无差异,均能够较好地快速检测出酮症。通过对乳汁中的酮体含量直接测定发现,直接法测定乳汁中的β-羟基丁酸平均含量完全落在乳酮症试纸条所规定的判定标准范围之内。此试验表明乳酮症试纸条能够较好地帮助奶牛场进行酮病的诊断,且使用较为方便,具有较强的推广使用前景。     

Plasma lipids in normal cows around partus and in cows with metabolic disorders with and without fatty liver

Free fatty acids, cholesterol and phospholipids in plasma were studied from 6 weeks before to 6 weeks after calving in 16 normal multiparous cows. The same plasma lipids were studied the day after calving in 20 normal primiparous cows. Ten of these were fed according to standards and the other 10 were overfed the last 3 weeks prepartum. The plasma lipids were also analysed in 16 cows with left displacement of the abomasum and fatty liver, and in 16 cows with ketosis with no or only slight fat infiltration of the liver. In the normal cows there was a rise in FFA-level and a reduction in cholesterol and phospholipids from 6 weeks before to the day after calving. Thereafter there was a reduction of FFA-level and rise in cholesterol and phospholipids. Increased feed intensity had no effect on plasma lipids at calving. The level of the plasma lipids in cows with fatty liver differed very much from the amounts in normal cows at corresponding time from calving. Cows with ketosis had high FFA-level but the amount of cholesterol and phospholipids differed very little from normal cows.     

Bovine mastitis and its association with selected risk factors in smallholder dairy farms in and around Bahir Dar,Ethiopia

Three hundred fifty one (195 local zebu and 156 Holstein x local zebu crosses) lactating cows of smallholder farms in Bahir Dar 'milk shed' were examined from September 2003 to March 2004 to determine mastitis prevalence, isolate pathogens and identify the role of some potential risk factors. Clinical prevalence was determined through examination of abnormalities of milk, udder or cow. California mastitis test (CMT) was used for determination of subclinical mastitis prevalence. Clinical prevalence at cow level was 3.9% in crossbreds and none in local zebu breeds. Subclinical mastitis at cow level based on CMT was high (34.4%) in crossbreds compared to indigenous zebu (17.9%) (p < 0.05). Quarter subclinical prevalence based on CMT was 17.9% and 4.9% in crossbreds and local zebu, respectively. The pathogens isolated from mastitic milk (CMT positive milk) were coagulase negative staphylococci (CNS), S. aureus, Str. agalactiae, Str. dysgalactiae, Str. uberis, Micrococcus species, C. bovis, A. pyogens, B. cereus, and S. intermedius. Among these, the most frequent isolates were CNS (50%), S. aureus (19%), Str. agalactiae (8%) and Str. dysgalactiae (7%). Among potential risk factors considered, stage of lactation, parity and breed were found to affect the occurrence of mastitis significantly (p < 0.05).     

Flock-level case-control study of slaughter-lamb pneumonia in New Zealand

Subclinical pneumonia is common in production lambs, and causes reductions in growth rate. We selected farms from meat-inspection records of three New Zealand abattoirs from December 2000 to May 2001 to study risk factors for flocks having ≥3% of their lambs with ≥10% of the lung surface with lesions, compared to flocks with a zero lamb-level prevalence of such pneumonia. A questionnaire of management practices was mailed to participating managers of case and control farms and we received responses from 132/192 (69%) cases and 181/300 (60%) in control farms. Risk factors for case farms were shearing lambs on the day of weaning (OR 6.4), breeding ewe replacements on-farm (OR 4.0), and the percentage of lambs sold between March and May (OR 1.0 for <23% sold (reference category), OR 3.9 for 23–42% sold, OR 2.7 for 43–64% sold, OR 4.3 for >64% sold). Protective factors included: grazing lambs at a fixed stocking rate after weaning (OR 0.4), injecting lambs with vitamin B12 at the time of docking (OR 0.4), and at the time of weaning (OR 0.3). Path analysis was used to show important associations between risk and protective factors differentiated according to time (e.g. before and after birth, at weaning and during growth on pasture). Flocks breeding their own ewe replacements were more likely to shear lambs at weaning, were less likely to buy lambs post-weaning and more likely to have ill-thrift present in >5% of lambs post-weaning. The purchase of lambs post-weaning was indirectly associated with greater odds of pneumonia at slaughter.     

围产期酮病奶牛血液生化指标特征分析

试验随机选取产前奶牛29头,跟踪采集产前2周、产前1周、分娩当天及产后3,7,14,21 d的血浆样品,检测血浆相关生化指标变化特征,并记录泌乳量。任意采集时间点血浆β-羟丁酸(BHBA)≥1.2 mmol/L则为酮病组, BHBA<1.2 mmol/L则为对照组。结果显示:随机选取的牛群中酮病发病率为58.6%,酮病主要发生在产后7～14 d;酮病组奶牛产前血液相关生化指标与对照组相比无显著性差异;与对照组相比,酮病组奶牛分娩当天血钾水平升高,血磷水平显著降低;产后3 d酮病组奶牛血浆甘油三酯、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)、BHBA、泌乳量显著高于对照组奶牛;产后7,14,21 d血浆BHBA、非脂化脂肪酸(ENFA)、TC、HDL-C、低密度脂蛋白胆固醇(LDL-C)水平极显著高于对照组奶牛,血糖水平显著低于对照组奶牛。二元Logistic回归分析显示:产后3 d血液TC、HDL-C、K、BHBA、泌乳量与奶牛酮病的发生显著相关。将显著性相关指标利用Logistic回归建模,最终建立了基于血液HDL-C、BHBA、泌乳量的奶牛酮病早期诊断模型,即y=17.95-9.81×HDL-C-2.71×BHBA-0.20×泌乳量,当y<0时存在发生酮病风险,模型早期预测奶牛酮病的准确率82.8%、灵敏度81.3%、特异性84.6%。     

循环外泌体在酮病奶牛肝脏脂代谢紊乱中的生理作用

奶牛酮病是由能量负平衡引起的,是围产期常见代谢紊乱性疾病。外泌体是含有膜蛋白、封闭胞质蛋白和RNA的磷脂双分子层的膜泡,可以传递信息并调节机体细胞的生理状态。本文就循环外泌体对奶牛肝脏脂代谢的影响、对腺苷酸活化蛋白激酶α/沉默信息调节因子1(AMPKα/SIRT1)通路的调节作用,以及作为酮病奶牛肝脏脂代谢紊乱诊断标志物的研究现状进行综述,有助于探究奶牛循环外泌体对酮病奶牛肝脏脂代谢紊乱的修复效果和作用机制,为寻找合适的酮病靶向治疗药物提供理论和实践依据。     

An association between the level of oxidative stress and the concentrations of NEFA and BHBA in the plasma of ketotic dairy cows

The aim of this study was to evaluate the oxidative status in ketotic cows. We observed changes in the oxidative status and correlations between the oxidative and metabolic status in non‐ketotic (n = 10), subclinical ketotic (n = 10) and ketotic cows (n = 10). Plasma samples were analysed by standard biochemical techniques and ELISA to determine traditional metabolic parameters: triglyceride (TG), phosphonium (P), calcium (Ca), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total protein (TP), albumin (ALB), immune globulin (Ig), total cholesterol (TC), high‐density lipoprotein (HDL), very low‐density lipoprotein (VLDL) and lactate dehydrogenase (LDH); energy metabolism indices: glucose, β‐hydroxybutyrate (BHBA) and non‐esterified fatty acids (NEFA); and indices of oxidative status: malondialdehyde (MDA), hydrogen peroxide (H₂O₂), vitamin C, vitamin E, superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), catalase (CAT), xanthine oxidase (XOD) and total antioxidant capacity (TAOC). The results of this study showed that plasma glucose levels were lower in ketotic and subclinical ketotic cows than in non‐ketotic cows; however, the plasma NEFA and BHBA concentrations were higher. In addition, significant decreases in TC, HDL and VLDL and significant increases in AST, ALT and LDH were observed in the plasma of the ketotic cows. The ketotic cows showed decreased plasma SOD, CAT, vitamin C and vitamin E, inhibited hydroxyl radical capacity and increased plasma H₂O₂ and MDA. There were positive correlations between the plasma NEFA and ALT, AST, LDH and MDA and negative correlations between the plasma NEFA and TC, HDL, VLDL, SOD, vitamin C, vitamin E, 1542280 uric acid and inhibited hydroxyl radical capacity. In addition, there were positive correlations between BHBA concentrations and ALT, AST and LDH and negative correlations between plasma BHBA concentrations and TC, HDL, VLDL, vitamin E and inhibited hydroxyl radical capacity. Overall, ketotic dairy cows experience oxidative stress, which is presumably associated with hyperketonemia and higher NEFA.     

营养对奶牛围产期健康的影响

在奶牛围产期,营养状况直接影响到奶牛疾病的发生。对于高产奶牛,由于奶牛体内的钙流失或者能量出现负平衡,容易产生乳热、酮病、脂肪肝等疾病,通过改善妊娠后期奶牛营养可减少这些疾病的发生。围产期奶牛的感染性疾病的易感性取决于免疫系统的完整性,而营养因素可影响机体免疫功能;其它非感染性疾病也可以通过改善营养状况来加以预防。     

Effect of bromelain on milk yield,milk composition and mammary health in dairy goats

A 7 month prospective cohort study was designed to determine if feeding bromelain to dairy goats influenced the MSCC, milk yield, milk composition and the incidence of IMI. Forty-four clinically normal goats from 2nd to 6th parities were studied. Daily bromelain dosage was 7.4 grams/animal (185-mg/Kg weight). Samples for diagnostic bacteriology were collected from each udder half every 2 weeks. Samples for MSCC and composition were obtained every 42 days. Milk yield was also recorded every 42 days. Bromelain affected milk protein and fat but not MSCC, milk yield or milk lactose. Bromelain did not decrease the MSCC in healthy goats. Milk protein and fat increased in the bromelain treated group (P < 0.01), which is important for dairymen because premiums are paid milk fat and protein content. No clinical mastitis was detected in the goats for the total study period and incidence rate of subclinical IMI was 5.7%. Relative risk was 1.50 (0.28 < RR < 8.12) which means that the bromelain had no significant effect on IMI (P > 0.05). In addition, the use of pineapple by-products could be especially important in tropical countries were pineapple waste seems to be a pollution problem.