Plasma Levels of Immunoreactive Parathyroid Hormone in Relation to Starvation Hypocalgaemia in Dairy Cows

The hypocalcaemia caused by parturition and onset of lactation in high-production dairy cows was mimicked by subjecting cows to starvation periods before and after partus. The changes in plasma calcium, phosphate and magnesium were followed and compared with immunoreactive parathyroid hormone (iPTH) in 2 cows. During the starvation periods before partus, the cows developed hypocalcaemia with no or only small changes in the plasma concentration of magnesium. After the onset of hypocalcaemia, the concentration of iPTH increased on the average 3–4-fold and the raised hormone levels lasted about 24 h after start of refeeding. An increase in plasma phosphate occurred somewhat later than the rise in iPTH and lasted longer. After partus hypocalcaemia developed, together with smaller increases in iPTH concentration (about 2-fold). The post-partum starvation period again resulted in hypocalcaemia and raised iPTH concentrations.In conclusion, starvation and parturition induced inverse changes in plasma calcium and iPTH in dairy cows. The increases in plasma iPTH were reversible and considered secondary to the hypocalcaemia. Through the effect of paratyroid hormone, plasma calcium was normalized and phosphate concentration increased. Therefore, fatal hypocalcaemia which may occur following the course of parturition and onset of lactation is not due to impaired PTH secretion.     

Experimental maedi infection in sheep. 1. Detection of virus, clinical course, histopathology

Eight sheep were inoculated with Icelandic maedi strain M 88; 2 sheep served as control sheep and were in close contact with the inoculated ones. Four of the sheep were inoculated via the respiratory tract with 7×10⁶ TGID50 of strain M88 and the other 4 intracerebrally with 5×10⁵ TGID50 of the same strain.Maedi M88 strain was isolated from peripheral blood leukocytes of all inoculated sheep. There was a striking difference between the 2 groups in the appearance of demonstrable viremia after inoculation. Viremia could be demonstrated in the intrapulmonarily inoculated sheep within 2–6 months but not until 8–11 months after inoculation in the intracerebrally inoculated ones. This finding is thought most probably to reflect a weak neurotropism of the strain used. After the first demonstration of viremia, maedi virus has been recovered quite reqularly in peripheral leukocytes of all intrapulmonarily inoculated sheep, but less regularly in the intracerebrally inoculated ones. Maedi virus was isolated from 1 of the uninoculated control sheep 15 months after inoculation.The first clinical case with a clinical appearance suggesting combined involvement of maedi and visna was found among the intrapulmonarily inoculated sheep, 8% months after inoculation. Histopathological examination and virus isolation confirmed maedi. The cause of paraplegia could not be confirmed. No histopathological changes were found and no virus isolation was made from the central nervous system of this animal.One of the intracerebrally inoculated sheep died suddenly without any observed clinical signs 11 months after inoculation. Histopathological examination revealed pulmonary lesions of maedi, but no visna lesions in the central nervous system, although maedi virus was isolated from various parts of brain.None of the other experimental sheep displayed clinical signs of maedi or visna during the observation period of 18 months.     

Duration of Effects of Phenylbutazone on Serum Total Thyroxine and Free Thyroxine Concentrations in Horses

The objectives of this study were to determine if phenylbutazone decreased serum thyroxine (TT₄) and free thyroxine (FT₄) concentrations using radioimmunoassay and equilibrium dialysis techniques in horses, and, if so, an additional objective was to determine the duration of this decreased concentration once phenylbutazone administration was discontinued. Serum TT₄ and FT₄ concentrations were determined before and after administration of 4.4 mg/kg of phenylbutazone IV bid for 5 days. Treatment with phenylbutazone caused a significant decrease in TT₄ and FT₄ concentrations ( P < .05). Serum TT₄ concentration significantly decreased after day 4 of treatment and remained significantly below baseline value for 10 days after discontinuing phenylbutazone administration; it returned to a value not different from the baseline value by the 11th day. Serum FT₄ concentration significantly decreased after day 4 of treatment and remained significantly below the baseline value for only 1 day after phenylbutazone administration was discontinued; it returned to a value not different from the baseline value by the 3rd day after discontinuation of phenylbutazone. These results indicate that serum TT₄ and FT₄ should not be used to evaluate thyroid function in horses receiving phenylbutazone. In addition, results should be interpreted cautiously when phenylbutazone has been administered within 2 days (for FT₄) or within 10 days (for TT₄) of sample collection.     

奶牛血孢子虫病的临床症状及防治

血孢子虫病是奶牛的一种常见疾病,该病主要是由牛双芽巴贝斯焦虫、牛巴贝斯焦虫、牛环形泰勒焦虫和边虫四种寄生虫感染导致的。患病奶牛主要表现为体温升高、黄疸、生产性能下降以及贫血等症状,对我国奶牛养殖业危害较大。本文就奶牛血孢子虫病的病原、临床症状、诊断治疗等方面进行论述,以加强奶牛场的饲养管理,加强营养供给,做好寄生虫的驱杀工作,降低该病的发生率和养殖场（户）的经济损失,为奶牛健康养殖提供理论基础。     

夏季热应激对奶牛的影响及预防措施

夏季热应激会降低奶牛的生产性能,影响养殖行业的经济效益,严重制约畜牧业的发展。因此牧场热应激的防控工作显得尤为重要。本文就热应激对奶牛的行为、采食量、繁殖性能的影响等进行综述,探讨缓解热应激的措施,以期帮助牧场管理人员制定预防热应激的策略。     

奶牛血乳症的病因、诊断与治疗方法

奶牛血乳症是由于奶牛乳房中输乳管、腺泡周围组织血管发生充血,血管壁明显扩张而破裂,导致血管中血红蛋白或红细胞进入输乳管、腺泡,从而分泌出的牛乳混有红色血液及血块的一种疾病。通常情况下该病可通过改善饲养管理条件而痊愈,但严重者需要加以药物治疗,否则会诱发奶牛乳房炎等其他疾病,导致奶牛泌乳量下降甚至死亡,而给奶牛养殖业带来严重的经济损失。本文通过对奶牛血乳症的机械性损伤、中毒、感染等多种发病原因进行深入分析,对该病临床症状和诊断方法进行阐述,提出西医和中西等不同手段的防治措施,并以实例进行了举证,为奶牛的健康养殖提供理论支持。     

奶牛热应激营养调控研究进展

热应激会对奶牛的生产性能、免疫性能、繁殖性能等造成不良影响,严重时甚至会威胁奶牛生命健康,给奶牛生产带来了巨大的经济损失.奶牛热应激目前已成为奶业健康发展急需解决的重要问题之一.该文总结了热应激的危害及其营养调控措施,旨在为缓解奶牛热应激提供解决方案以及较为全面的参考.     

热应激对奶牛繁殖力的影响及应对措施

炎热的夏季会导致奶牛的繁殖力下降,其原因是由于热应激引起动物机体一系列的异常反应所致。本文通过总结近十几年国内外的研究成果,从内分泌、配子产生和胚胎发育等方面论述了热应激对奶牛繁殖力的影响及可能存在的内在机制,并针对这些影响提出了一系列在奶牛生产中用于缓解热应激和提高奶牛繁殖力的措施,包括常用的奶牛物理降温法、日粮调配、耐热性奶牛的培育,以及具有广阔前景的生物技术等。     

不同温湿指数环境下奶牛阴道温度的变化规律

为探究不同温湿指数(THI)环境下奶牛阴道温度的变化规律,试验分别在高THI(78.5±3.2)、中THI(70.4±4.1)、低THI(56.3±5.5)环境下连续7d监测15头健康妊娠奶牛的阴道温度及所在牛舍内外的温度和相对湿度。结果表明:高THI环境下奶牛平均阴道温度、日极值均差、测期极值差极显著高于中、低THI环境下奶牛相应的测值(P<0.01);奶牛日平均阴道温度和日平均THI、日最高阴道温度和日受热时长的相关系数r分别是0.811、0.896(P<0.01);引起日平均阴道温度、日最高阴道温度开始快速升高的日平均THI、日最大THI分别为71.4、77.3,日受热时长为10.6h时日最高阴道温度变化出现拐点。由此可见,高THI环境下奶牛阴道温度变化幅度大;相比THI,日受热时长会影响奶牛阴道温度的变化。     

奶牛热应激与营养调控研究进展

热应激是导致奶牛夏季产奶性能、繁殖性能和免疫能力下降的最主要原因之一。由于夏季高温时间长，热应激作用会造成奶牛业巨大的经济损失。因此，奶牛热应激机制及其对策的研究受到国内外广泛重视。为缓解奶牛热应激采取的主要措施包括营养调控、环境改善和育种途径。由于生产成本和荷斯坦品种相对耐     

热应激对荷斯坦奶牛体温和呼吸的影响

本试验旨在研究热应激对不同泌乳阶段奶牛直肠温度、皮肤温度和呼吸频率的影响。选用不同泌乳阶段、胎次相近的荷斯坦奶牛18头,按泌乳天数分为泌乳前期、泌乳中期和泌乳后期3组,每组6个重复,根据牛舍温湿指数(THI)变化情况,进行热应激与非热应激的自身对照试验。结果表明:热应激极显著增加各泌乳阶段奶牛的直肠温度、皮肤温度和呼吸频率(P<0.01);THI与各泌乳阶段奶牛的直肠温度、皮肤温度、呼吸频率呈显著正相关(P<0.05);在同一环境下,不同泌乳阶段奶牛的直肠温度、皮肤温度及呼吸频率无显著差异(P>0.05)。热应激严重影响奶牛的直肠温度、皮肤温度和呼吸频率,与泌乳中、后期奶牛相比,热应激对泌乳前期奶牛的影响趋于较大。     

喷雾吹风和淋水吹风对奶牛热应激的影响

试验选用三头产奶量、体况、胎次相近的荷斯坦奶牛,按3×3拉丁方设计,试验期每天14：30至17：00对试验牛分别进行间歇性喷雾吹风、间歇性淋水吹风和对照处理,观察与测定试验牛的生理指标和血液生化指标等。试验结果表明,喷雾吹风组和淋水吹风组在肌酸磷酸激酶、三碘甲腺原氨酸（T3）指标上均差异显著：淋水吹风组与对照组奶牛比较,在呼吸频率、三碘甲腺原氨酸（T3）指标上差异显著;喷雾吹风组与对照组比较．在呼吸频率上差异显著,在三碘甲腺原氨酸（T3）指标上无显著差异。直肠温度、平均皮温、产奶量,血红蛋白、红细胞数、白细胞数和红细胞压积,甲状腺素和皮质醇,谷丙转氨酶、谷草转氨酶、碱性磷酸酶和乳酸脱氢酶,Na^＋、K^＋、Cl^-、Ca^2＋和Mg^2＋浓度等指标各组间均无显著差异（P〉0．05）,但处理组各指标相对于时照组均有下降趋势。综合各项指标考虑喷雾吹风和淋水吹风对热应激奶牛有一定改善效果,在高温高湿天气里淋水吹风的降温效果比较好。     

植物黄酮在缓解奶牛热应激上的应用前景

奶牛是一种耐寒畏热的动物,当奶牛对环境温度的适应能力超过其阈值时就会产生热应激。热应激对奶牛的生产性能、抗氧化能力、免疫机制、内分泌和代谢产生不利影响,是阻碍奶牛业健康发展的一大问题。近年来,植物提取物作为一种兼具营养价值和保健价值的饲料添加剂被广泛应用。植物黄酮作为一种存在广泛的植物提取物,具有提高家畜生产性能和抗氧化能力、增强机体免疫力和抗炎能力、调节机体代谢等功效。因此,植物黄酮可以对症治疗奶牛热应激。本文将从热应激对奶牛生产性能、抗氧化能力、免疫机制、内分泌和代谢的影响以及近些年来将植物黄酮用于改善动物热应激的相关研究进行综述,以期为植物黄酮用于缓解奶牛热应激的深入研究提供理论支持。     

Evaluation of Thyroid‐Stimulating Hormone,Total Thyroxine,and Free Thyroxine Concentrations in Hyperthyroid Cats Receiving Methimazole Treatment

Background

Iatrogenic hypothyroidism (IH) after treatment of hyperthyroidism can impair renal function. No study compared the efficacy of measurement of serum free thyroxine by equilibrium dialysis (fT4ed) or thyroid‐stimulating hormone (TSH) concentrations for monitoring cats receiving methimazole.

Objectives

To (1) compare the ability of total T4 and fT4ed concentrations in conjunction with TSH to define thyroid function in hyperthyroid cats receiving methimazole, (2) determine the prevalence of IH in cats receiving methimazole, and (3) examine the relationship between thyroid axis hormones and serum creatinine concentration.

Animals

One hundred and twenty‐five serum samples from hyperthyroid cats receiving methimazole and total T4 concentrations ≤3.9 μg/dL.

Methods

Total T4, fT4ed, and TSH concentrations were measured to evaluate thyroid status and serum creatinine concentration was measured to assess renal function. A low total T4 or fT4ed concentration in combination with an increased TSH concentration defined IH.

Results

Forty‐one cats (33%) had increased TSH concentrations. Of cats with total T4 and fT4ed concentrations below the reference range, 68% and 73%, respectively, had TSH concentrations above the reference range. Only 18% of cats with a normal TSH concentration had an increased serum creatinine concentrations as compared to 39% of those with increased TSH concentrations (P < .001).

Conclusions

Free T4ed does not identify more cats with potential IH as compared to total T4. The IH prevalence was approximately 20%. Measurement of TSH may be more helpful in indicating that azotemia, if present, is at least in part related to IH. Investigation is needed to define TSH assay utility in identifying possible subclinical IH.     

壳聚糖对乳房炎奶牛血清自由基代谢的影响

目的:探讨壳聚糖对乳房炎奶牛血清自由基代谢的影响。方法:选择产奶量、胎次和泌乳期相近,营养中等,乳房炎阴性6头,阳性30头,组成0(阴性对照组)、1(阳性对照组)和2、3、4、5组(试验组),每组6头。各组基础日粮相同。分别在各组基础日粮中添加壳聚糖0、0、10、20、40和80g/d·头。连续饲喂2周。分别于试验前(0周)、1周和2周采取血样,分离血清,测定血清SOD、CAT、GSH-Px活力和MDA、NO的含量。结果:饲喂壳聚糖后,各组血清SOD与GSH-Px活力显著升高,血清MDA含量显著降低。各试验组奶牛血清CAT活力均有升高的趋势,血清NO含量有降低的趋势,但差异均不显著(P>0·05)。结论:壳聚糖具有提高乳房炎奶牛血清SOD和GSH-Px活力,降低血清MDA的含量,提高机体抗氧化能力,改善血清自由基代谢水平和促进炎症康复的作用。但对血清CAT和NO基本没有影响。     

中药复方灌注液对奶牛急性子宫内膜炎临床疗效观察

为了考察中药复方灌注液对奶牛子宫内膜炎自然病例的临床治疗效果,将确诊患有急性子宫内膜炎的病牛40头,随机分为5组(A组~E组),每组8头,其中A、B、C组分别为中药复方灌注液高、中、低剂量组,分别子宫内灌注中药复方灌注液150、100、50mL/次,隔天1次,连用3次;D组为阳性药物对照组,子宫内灌注双黄连注射液100mL/次,隔天1次,连用3次;E组为疾病对照组,不给药,另选择临床健康奶牛8头作为健康对照组(F组),不给药。结果表明,中药复方灌注液能显著降低急性子宫内膜炎病牛子宫颈口黏液白细胞数和血液白细胞数,临床症状明显改善,其中高、中剂组效果较好,说明该中药复方灌注液对奶牛急性子宫内膜炎自然病例具有显著治疗效果,推荐临床使用剂量为100mL/次,隔天1次,连用3次。     

益康XP对奶牛血浆内毒素含量及其他指标的影响

选取泌乳天数<40 d的健康奶牛 12头,按胎次、泌乳天数和产奶量相同或相似的原则,分为试验组和对照组。两组日粮组成相同,试验组牛每天添加益康XP的剂量为试验第1天至第7天500 g/(头·d),从第 8 天后减少到120 g/(头·d),分两次饲喂。试验期为60 d。于试验前 1 天,试验第 20 天,40天和第 60 天分别采血,用鲎试剂法测定血浆内毒素含量;定期测定日均产奶量、乳脂率、乳蛋白率和体细胞数;记录情期受胎率及疾病发生情况。结果表明,试验组奶牛在试验后第20天,第 40 天和第 60 天血浆内毒素均极显著低于对照组(P<0.01);产奶量在第20天,第60天显著高于对照组(P<0.05);两组奶牛乳脂率、乳蛋白率、体细胞数差异均不显著(P>0.05);试验组情期受胎率极显著高于对照组(P<0.01);在疾病发生率方面,试验组极显著低于对照组(P<0.01)。     

乏情奶牛日粮营养水平和血浆生殖激素的变化

选取产后65～75天无发情表现的泌乳奶牛，经直检分为卵泡闭锁（Ⅰ）、卵巢囊肿（Ⅱ）、持久黄体（Ⅲ）和排卵延迟（Ⅳ）4组，每组10头奶牛。应用放射免疫测定法检测每头奶牛血浆FSH、LH、E2、P4的水平，同时分析该牛场此时期日粮中营养水平。结果表明：饲料中能量、蛋白质和磷的含量低于NRC（2001）水平。4个组奶牛血浆中的FSH含量均低于正常水平；Ⅰ组血浆中的E2含量低于同期正常水平；Ⅱ组血浆中的E2含量高于正常水平；Ⅲ组血浆中的E2含量低于正常水平，P4的含量高于正常水平；Ⅳ组血浆中的E2含量高于正常水平，P4和LH的含量低于正常水平。结论：日粮能量、蛋白和磷含量较低导致的泌乳奶牛生殖激素的紊乱是引起奶牛乏情的主要因素。     

热应激条件下荷斯坦奶牛后段肠道差异微生物分析

本试验旨在分析热应激条件下,热应激耐受奶牛和热应激易感奶牛后段肠道菌群组成的差异,寻找与热应激相关的后段肠道微生物,为利用饲养管理和遗传选择等手段提高奶牛耐热能力提供理论依据。选择体况相近且健康的1胎中国荷斯坦泌奶牛19头,利用奶牛夏季上午直肠温度（MRT）和下午直肠温度（ART）差值（RTD）将其分为热应激易感组（H组,10头）和热应激耐受组（L组,9头）。采用Illumina PE250测序平台测定两组个体粪便中细菌16S rDNA V3~V4区序列,利用生物信息学方法筛选两组个体的差异微生物。结果表明：①L组的Shannon指数和Chao1指数高于H组,但组间差异不显著（P>0.05）。②在门水平,两组个体的厚壁菌门（Firmicutes）、拟杆菌门（Bacteroidetes）和变形菌门（Proteobacteria）的相对丰度之和均占总菌的95%以上;在属水平,L组中YRC22和普雷沃氏菌属（Prevotella）的相对丰度显著高于H组（P<0.05）,且YRC22、Prevotella的相对丰度与ART、RTD、呼吸评分（RS）、直肠温度极值（RTR）及流涎评分（DS）等5项热应激相关指标均呈负相关关系。③与热应激相关的6项指标（MRT、ART、RTD、RS、DS、RTR）中,RS、DS和MRT在冗余分析（RDA）结果中R2较大,表明这3项指标与奶牛后段肠道微生物菌群相关程度较大。综上所述,热应激影响奶牛后段肠道菌群结构,Prevotella是热应激相关的后段肠道微生物。