Pestivirus in cattle: experimentally induced persistent infection in calves

Twenty-two heifers were infected intranasally with non-cytopathic bovine viral diarrhoea virus (BVDV) between days 74 and 82 of pregnancy. All animals had developed serum antibodies against BVDV 5 weeks later. No clinical effects were seen in the heifers, and they all delivered a live calf. The newborn calves were generally small, appeared unthrifty as typical 'poor doers', and some developed secondary infections with diarrhoea and signs of respiratory disease. Eighteen of the 22 calves were born without antibodies against BVDV and were persistently infected (PI) with the virus. One was weak at birth and died the following day. Four calves were born with serum antibodies against BVDV and with no detectable virus. Three of these showed signs and/or pathological changes indicating disease in the central nervous system. Otherwise, there were no obvious clinical differences between these calves and the PI calves, nor were there any apparent significant differences in blood parameters between these groups. In general, the calves showed low gamma-globulin values and thrombocytopaenia, but moderately increased fibrinogen values and relatively normal lymphocyte numbers.     

Serum from heifer calves treated with bovine growth hormone affects the rate of proliferation of C2C12 myogenic cells dependent on the plane of nutrition: the role of insulin-like growth factor-I and IGF-binding proteins-2 and -3

The present in vitro experiments were carried out in order to study whether variations in the bovine growth hormone (bGH)/insulin-like growth factor (IGF)-I axis induced by plane of nutrition and bGH treatment of heifer calves caused variations in serum-induced proliferation of C2C12 myoblasts. Serum was obtained from two groups each of six heifer calves (195 +/- 8 kg) before (d -1) and after treatment with 15 mg/day of bGH for 6 days (d 6) fed either a low (GHL) or a high plane (GHH) of nutrition. Preceding the experiment all 12 heifer calves were fed at the low plane of nutrition. At d 6, serum concentrations of insulin and IGF-I were increased while that of IGF-binding proteins (IGFBP)-2 was decreased in GHH, but unchanged in GHL calves. Serum-induced proliferation of C2C12 myoblasts, was elevated at d 6 by GHH treatment. Especially human IGFBP-3 but also bovine IGFBP-2 added to cell cultures inhibited the rate of proliferation of C2C12 myoblasts stimulated by human IGF-I. The present results showed that GH treatment causes changes in the GH/IGF axis, which leads to changes in serum-induced growth of C2C12 muscle cells dependent on the plane of nutrition that mimic in vivo effects of GH treatment, which indicate an endocrine contribution of the IGF system. However, drawbacks of this suggestion are discussed.     

Pathologic changes, tissue distribution, and extent of conversion to ethylenethiourea after subacute administration of zinc ethylene-bis-dithiocarbamate (zineb) to calves with immature rumen function.

The toxicity of zinc ethylene-bis-dithiocarbamate (zineb), a widely used fungicide, was studied in four 4-week-old Friesian calves with immature rumen function. Calves were first subjected to liver biopsy, and thereafter, 3 of them were orally administered 200 mg of zineb/kg of body weight daily for 80 days, whereas the fourth calf served as control and remained untreated. Clinical, hematologic, and pathologic (including ultrastructural) findings were recorded. The distribution in body fluids and tissues of the parent compound and one of its main metabolites, ethylenethiourea (ETU), also was examined. Treated calves had unthrifty appearance and reduction in weight gain. They also had remarkable impairment of thyroid function, as reflected by reduction in serum concentrations of triiodothyronine and thyroxine and increase in weight of the thyroid gland associated with epithelial vacuolization and foci of hyperplasia. Moderate increase in liver glycogen content and impairment in maturation of germ cells were recorded consistently. Whereas zineb was widely distributed in body tissues, ETU accumulated mainly in the liver and the thyroid gland, although noticeable concentrations also were attained in muscle. Data were consistent with involvement of ETU mainly in the pathogenesis of thyroid gland lesions, and indicate that unweaned calves given zineb develop a clinicopathologic syndrome that does not differ qualitatively from that already described in adult cattle exposed to zineb.     

Clinical evaluation of growth hormone secretion in cattle using insulin tolerance test

Growth hormone secretion was evaluated in cattle. Clinically healthy bovine growth hormone (bGH) concentrations were 10.7 +/- 1.6 ng/ml in Holstein and 7.8 +/- 3.9 ng/ml in Japanese black cattle. The bGH concentration alternated at three-hour intervals, and tended to be higher at midnight and lower in the morning and before feeding. Insulin tolerance test (ITT) at an insulin dosage of 0.25 U/kg showed a significant increase of bGH concentration to 331 +/- 153% at 60 to 90 min after injection. In ITT applied to five under-growth calves of Japanese black cattle, the basal bGH concentrations were lower and peak values after insulin injection were shown to be significantly low. The ITT is useful for the clinical examination of bGH secretion in cattle.     

Winter outbreaks of laminitis in dairy calves: aetiology and laboratory, radiological and pathological findings.

During the winter months of 1984 to 1989, outbreaks of laminitis occurred in up to 6 per cent of all the dairy calves aged four to six months on a dairy farm in a village in Israel. The clinical signs were reluctance to move, an arched back, overgrown hooves, supracoronary swelling and occasional walking on the carpus; most of the calves were unthrifty. Owing to the regular recurrence of the disease, the feeding and haematological, radiological and pathological changes in both the affected and normal calves at the farm, and in normal calves at another farm in the same village were studied. In the affected calves there were significant increases in serum protein concentration and in the activities of creatine phosphotinase and gamma-glutamyltransferase. Radiography showed dilated PIII vascular channels and some PIII rotation. Post mortem studies revealed haemorrhages in the laminar section of the hoof. The management of the farms differed in the protein level of the milk replacer and the 'starter' diet used during the first few months. The affected farm used feeds containing 18 per cent digestible protein whereas the unaffected farm used feeds containing 15.3 per cent digestible protein.     

外源生长激素在延边黄牛上的试验研究(Ⅲ)——对血液生理生化指标的影响

为阐明外源生长激素对延边黄牛血液生理生化指标的影响。试验 1选用 2 0头体重、月龄相近的延边黄牛育成牛 (阉牛 ) ,按体重随机分为试验组和对照组。试验组每 1 4d注射 1次 0 .4 2mg/kgBW的生长激素 ,对照组不注射 ,持续 1 6 8d ,进行了外源生长激素对延边黄牛育成牛血液生理生化指标影响的研究。结果表明 ,试验组的血清葡萄糖 (P <0 .0 5 )和血清钙 (P <0 .0 5 )含量均高于对照组 ,尿素氮 (P <0 .0 1 )含量低于对照组。血清总蛋白、清蛋白、球蛋白、总脂、磷含量试验组分别高于对照组 ,但差异均不显著 (P >0 .0 5 ) ,血清谷丙转氨酶 (GPT)和谷草转氨酶(GOT)含量两组基本相似。试验 2通过对 1 2头泌乳母牛及其哺育的犊牛研究表明 :泌乳母牛和犊牛的血清总蛋白、清蛋白、钙、葡萄糖、总脂、无机磷含量试验组均高于对照组 ,其中清蛋白含量差异极显著 (P <0 .0 1 ) ,母牛的血液指标中 ,血清总蛋白含量试验组高于对照组 (P <0 .0 1 ) ,血清非蛋白氮含量试验组与对照组之间没有差异。犊牛的血液指标中 ,血清总脂、非蛋白氮、谷草转氨酶含量试验组均低于对照组 ,但差异不显著     

Effect of progressive cachectic parasitism and growth hormone treatment on hepatic 5'-deiodinase activity in calves

Thyroid status is compromised in a variety of acute and chronic infections. Conversion of thyroxine (T₄) into the metabolically active hormone, triiodothyronine (T₃), is catalyzed by 5′-deiodinase (5′D) mainly in extrathyroidal tissues. The objective of this study was to examine the effect of protozoan parasitic infection (Sarcocystis cruzi) on hepatic 5′D (type I) activity and plasma concentrations of T₃ and T₄ in placebo- or bovine GH (bGH)-injected calves. Holstein bull calves (127.5±2.0 kg BW) were assigned to control (C, ad libitum fed), infected (I, 250,000 S. cruzi sporocysts per os, ad libitum fed), and pair-fed (PF, non-infected, fed to intake of I treatment) groups placebo-injected, and three similar groups injected daily with pituitary-derived bGH (USDA-B-1, 0.1 mg/kg, i.m.) designated as C_GH, I_GH and PF_GH. GH injections were initiated on day 20 post-infection (PI), 3–4 days prior to the onset of clinical signs of the acute phase response (APR), and were continued to day 56 PI at which time calves were euthanized for liver collection. Blood samples were collected on day 0, 28, and 55 PI. Alterations in nutritional intake did not affect type I 5′D in liver. Treatment with bGH increased (P<0.05) 5′D activity in C (24.6%) and PF (25.5%) but not in I calves. Compared to PF calves, infection with S. cruzi reduced 5′D activity 25% (P<0.05) and 47.8% (P<0.01) in placebo- and bGH-injected calves, respectively. Neither nutrition nor bGH treatment significantly affected plasma concentrations of T₄ and T₃ on day 28 and 55 PI. However, plasma thyroid hormones were reduced by infection. On day 28 PI, the average plasma concentrations of T₃ and T₄ were reduced in infected calves (I and I_GH) 36.4% (P<0.01) and 29.4% (P<0.05), respectively, compared to pair-fed calves (PF and PF_GH). On day 55 PI, plasma T₃ still remained lower (23.7%, P<0.01 versus PF) in infected calves while plasma T₄ returned to control values. The data suggest that parasitic infection in growing calves inhibits both thyroidal secretion and extrathyroidal T₄ to T₃ conversion during the APR. After recovery from the APR, thyroidal secretion returns to normal but basal and bGH-stimulated generation of T₃ in liver remains impaired.     

青海省湟源县本地黄牛四项血清钙指标的测定

对30头湟源县本地黄牛的4项血清钙指标进行了测定。结果表明：犊牛的血清总钙、血清结合钙和血清游离钙含量均显著高于成年牛（P＜0．01），而两者的血清游离钙百分率相似（P＞0．05）。     

日粮中添加酵母培养物AYC-X6对犊牛生长发育的影响

[目的]为研究在犊牛日粮中添加酵母培养物对犊牛生长发育的影响。[方法]在宁夏固原现代农业园区肉牛繁育基地随机选取90头2.5月以上犊牛作为试验牛群,采用配对试验设计,试验分为2个处理组。[结果]结果表明,试验组犊牛比对照组犊牛平均干物质采食量提高了14.9%,日增重提高了24.6%,饲料消耗降低了0.08%。体重提高了24.1%,体高、胸围、腹围、体斜长分别提高了5.1%,11.3%,12.8%,24.9%。试验组粪便分离筛第1,2,3层筛上物分别为15%,20%,65%。试验组血清总蛋白(BSA)、球蛋白(BGG)含量均显著高于对照组,谷丙转氨酶(ALT)、谷草转氨酶(AST)、碱性磷酸酶(ALP)含量均显著低于对照组。[结论]在犊牛日粮中添加酵母培养物AYC-X6,能提高饲料消化率,促进犊牛生长发育,提高犊牛平均日增重和生长速度。提高血清总蛋白、球蛋白含量,降低谷丙转氨酶、谷草转氨酶、碱性磷酸酶水平,改善犊牛免疫能力。     

Changes in serum thyroid hormone levels in newborn calves as a diagnostic index of endemic goiter

Maximum serum thyroxine (T4) and triiodothyronine (T3) levels of healthy calves were seen at 1 day after birth, and thereafter rapidly decreased until 5 days after birth. They stabilized until 2 weeks after birth, then gradually decreased until 4 weeks after birth. Serum T4 levels of calves with endemic goiter tended to be lower than those of healthy ones, but showed similar levels to those of adult cows. T3 levels of calves with goiter were similar to those of healthy ones, but showed higher variation. T4/T3 ratio of calves with goiter were significantly lower than those of healthy ones and adult cows. While individual levels of serum T4 and T3 at just after birth could not be considered as a diagnostic index, the T4/T3 ratio could be adopted as a diagnostic index of endemic goiter.     

Effect of Weaning Stress on Blood Physiology and Biochemistry Indexes and Immune Function in Dairy Buffalo Calves

To study the effect of weaning stress on dairy buffalo calves,5 healthy calves were chosen and weaned,and the blood samples were collected at 1 day before weaning,and 1,14 and 21 days after weaning to analysis blood physiology and biochemistry indexes and immune function.The results showed that the count of white blood cell,lymphocyte,erythrocyte,monocytes and hematocrit,aspartate aminotransferase activity,blood glucose,cortisol and immunoglobulin G contents of dairy buffalo calves were no significant difference between before and after weaning treatments (P > 0.05).The count of neutrophils at 21 d after weaning were significantly lower than that of 1 d before weaning of dairy buffalo calves (P < 0.05).However,lactate dehydrogenase and alanine aminotransferase activity in weaned treatments were significantly higher than those of animals in the treatment before weaning (P < 0.05).The serum urea nitrogen of dairy buffalo calves at 21 d after weaning was significantly higher than that of 1 d before weaning (P < 0.05) and hemoglobin content at 21 d after weaning was significantly lower than that at 1 day before weaning (P < 0.05).It indicated that the physiological and immunity function of dairy buffalo calves were challenged under weaning stress.     

γ-聚谷氨酸对断奶犊牛血清生化指标的影响

[目的] 研究γ-聚谷氨酸对断奶犊牛血清生化指标的影响。[方法] 将体重相近的荷斯坦断奶犊牛16头,按同质原则分为对照组和试验组,每组8头。两组犊牛每天每头饲喂3 kg颗粒饲料,玉米秸秆随意采食。试验组颗粒饲料中按照千分之五的比例加入γ-聚谷氨酸（膏状液体,含量为20%）。试验时间70 d,预试期10 d,正试期60 d。在试验最后一天采集血液样品测定血清生化指标。[结果] 对照组犊牛血清中IgG、IgA和IgM含量显著（P<0.05）高于试验组;对照组犊牛血清中SOD、GSH-Px活性显著（P< 0.05）高于试验组;两组AST与ALT活性差异不显著（P>0.05）;对照组和试验组犊牛血清中TP、ALB、BUN、NEFA、GLU、Ca、P、Fe、Zn含量差异不显著（P>0.05）,试验组断奶犊牛血清中Cu、VA和VC含量显著（P<0.05）低于对照组。[结论] ①γ-聚谷氨酸会降低断奶犊牛血清中免疫球蛋白（IgG、IgM、IgA）的含量;②γ-聚谷氨酸有提高断奶犊牛机体抗氧化能力的可能;③γ-聚谷氨酸可能会促进断奶犊牛对Cu、VA和VC的吸收与利用;④γ-聚谷氨酸未对断奶犊牛肝脏功能、能量代谢、能量平衡、蛋白质利用产生负面影响。     

断奶应激对奶水牛犊牛血液生理生化指标和免疫功能的影响

为研究断奶应激对奶水牛犊牛的影响,选用5头健康犊牛,分别于断奶前1 d、断奶后1、14和21 d进行采血,测定犊牛的血常规、血清生化指标和免疫指标。结果显示,奶水牛犊牛的白细胞数、淋巴细胞数、红细胞数、单核细胞数、红细胞压积、天冬氨酸转氨酶活性、血糖含量、皮质醇含量、免疫球蛋白G含量在断奶前后无显著变化（P > 0.05）;中性粒细胞数在断奶后21 d显著低于断奶前1 d（P < 0.05）;血清乳酸脱氢酶、丙氨酸转氨酶活性在断奶后显著高于断奶前（P < 0.05）;血清尿素氮含量在断奶后21 d显著高于断奶前1 d（P < 0.05）;血红蛋白含量在断奶21 d显著低于断奶前1 d（P < 0.05）。结果表明断奶应激不仅影响了奶水牛犊牛的生理机能,而且降低了其免疫力和抵抗力。     

Genetic control of immunity to gastrointestinal nematodes of cattle

Previous studies have indicated that host genetics significantly affects the number of gastrointestinal nematode eggs per gram (epg) in the feces of calves during their first grazing season. An entire calf crop of approximately 190 animals was monitored monthly until weaning to verify these earlier results, and to begin to discern the basis for this phenomenon. A significant genetic effect on fecal epg values was not observed until calves had been on pasture for 2-3 months, and was demonstrable until late in the grazing season when the effect was lost. The loss of a genetic effect coincided with the appearance of significant numbers of the more highly fecund nematode species Haemonchus placei and Oesophagostomum radiatum, and with an apparent increase in Ostertagia ostertagi transmission, indicating that the observed genetic control of epg values may be species specific, dose dependent or both. Calves were selected from the population, and grouped according to their epg phenotype over the grazing season as either high or low epg calves. Postmortem examination of some of these calves indicated that worm burdens in the low epg calves were 60% of those of the high epg calves. Experimental challenge inoculation of the remaining calves indicated that: (1) challenge with Cooperia oncophora resulted in low epg calves harboring worm numbers that were 65% of those of high epg calves; (2) challenge with O. ostertagi resulted in similar numbers of worms in both groups, but the fecundity of worms in the low epg groups was significantly lower (P less than 0.05) than in the high epg group. Analysis of serum anti-Ostertagia antibody levels in the grazing calf population showed rises in serum IgG1, IgG2, IgM and IgA antibody levels during the grazing season. Peak serum IgG2 and IgG1 anti-Ostertagia antibody levels were found to be significantly affected by host genetic factors while IgA and IgM levels were not under such control.     

复合乳酸菌和酵母菌对新生犊牛免疫和抗氧化功能的影响

选择体况相同、体质量(36±2.53) kg、3日龄内的中国荷斯坦母犊牛40头,随机分为4组,每组10头,即空白组(D组)、乳酸菌组(L组)、乳酸菌+酵母菌组(LS组)、酵母菌组(S组).在试验期内,4组犊牛均全程饲喂代乳粉,LS、L和S组分别添加复合益生菌,D组不添加,试验期45 d.结果 表明:与试验1d相比,45...     

母牛补饲维生素E和硒对新生犊牛生长和免疫的影响

本试验选择年龄、胎次、体况评分、顸产期相近的中国荷斯坦奶牛40头,随机分成2组,一组自由舔饲维生素E富硒舔砖,一组不补饲舔砖,研究维生素E(VE)和硒对新生犊牛生长和免疫的影响.试验期90 d,从预产前60 d到产后30 d.结果表明,试验组母牛血清中VE的含量在产后12 h显著高于对照组(P<0.05),血清中硒的含量在产前30 d和产后12 h高于对照组,差异极显著(P<0.01).试验组母牛分娩后12 h,血清中IgG、IgM的含量,初乳中IgM、IgG、IgA的含量都显著高于对照组(P<0.05).试验组犊牛出生后12 h,血清中VE和硒含量极显著高于对照组(P<0.01),IgG、IgA的含量高于对照组,差异显著(P<0.05).试验组犊牛初生体质量和体尺显著高于对照组(P<0.05),30日龄体质量和体尺高于对照组,差异极显著(P<0.01).试验组犊牛的发病率比对照组降低了50%.     

Pituitary-testicular responses of estradiol-17 beta-implanted bull calves to continuous versus pulsatile infusion of luteinizing hormone releasing hormone

The luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone response of bull calves implanted with estradiol-17 beta to continuous and pulsatile infusion of luteinizing hormone releasing hormone (LHRH) has been examined. Estradiol-17 beta reduced serum LH and FSH concentrations and suppressed testosterone secretion and testicular growth when compared with sham-implanted bulls. Pulsatile iv infusion of LHRH [500 ng every 2 h (6 micrograms/d)] for a 4-wk period to estradiol-17 beta-implanted bulls resulted in elevated mean serum LH and testosterone concentrations that were characterized by discrete secretory episodes. Mean serum FSH was also increased by LHRH pulse infusion, but LHRH-coupled secretory episodes were not apparent. Continuous infusion of LHRH (6 micrograms/d) did not increase the low serum gonadotropin levels observed in estradiol-17 beta-implanted calves. Testicular growth was normal in LHRH pulse-infused calves, but was markedly curtailed in continuously infused calves. These results suggest that estradiol-17 beta inhibits testicular development by blocking gonadotropin release at the level of the hypothalamus because pulsatile administration of LHRH can override the inhibitory effect by increasing LH and FSH secretion.     

GH secretory responses to ghrelin and GHRH in growing and lactating dairy cattle

Release of growth hormone (GH) is known to be regulated mainly by GH-releasing hormone (GHRH) and somatostatin (SRIF) secreted from the hypothalamus. A novel peripheral release-regulating hormone, ghrelin, was recently identified. In this study, differences of the GH secretory response to ghrelin and GHRH in growing and lactating dairy cattle were investigated and an alteration of plasma ghrelin levels was observed. The same amounts of ghrelin and GHRH (0.3 nmol/kg) were intravenously injected to suckling and weanling calves, early and mid-lactating cows and non-lactating cows. Plasma ghrelin levels were also determined in dairy cattle in various physiological conditions. The peak values of ghrelin-induced GH secretion were increased in early lactating cows compared to those in non-lactating cows. The relative responsiveness of GH secretion to ghrelin was also increased compared with that to GHRH in early lactating cows. GH secretory responses to GHRH were blunted in mature cows with and without lactation. Conversely, GHRH-induced GH secretory response was greater than that to ghrelin in calves, and also greater in calves than in mature cows. Plasma ghrelin concentrations were elevated in early lactating cows compared to those in non-lactating cows. Plasma GH concentrations were higher in suckling calves and early lactating cows compared with those in non-lactating cows. These results suggest that GHRH is an effective inducer of GH release in growing calves, and that the relative importance of ghrelin in contributing to the rise in plasma GH increases in early lactating cows.     

母带犊牛与离母犊牛的血清代谢组学差异

本试验旨在比较母带犊牛和离母犊牛的血清代谢组学差异,为开发犊牛代乳粉提供方向。挑选8头健康且体重[（13.88±0.54） kg]接近的新生犊牛（牦牛■×犏牛♀）为母带犊牛组,犊牛随母哺乳;另外挑选8头体重[（13.75±0.82） kg]接近的新生犊牛（牦牛■×犏牛♀）为离母犊牛组,犊牛饲喂代乳粉。2组犊牛10 d后自由采食相同饲粮。试验期90 d。试验结束当天晨饲前对2组犊牛进行采血,采用超高效液相色谱-四极杆飞行时间质谱（UPLC-QTOF/MS）对血清样品进行代谢组学分析。以差异倍数（FC）、变量重要性投影（VIP）和t检验P值作为筛选依据,筛选标准为FC<0.5或FC>1.5、VIP>1和P<0.01。结果表明,共筛选出DL-3苯乳酸、D-山梨糖醇和橙皮素等共30个差异代谢物（FC<0.5或FC>1.5、VIP>1和P<0.01）。差异代谢物通路分析表明,与血清代谢物的改变最为相关的是D-谷氨酰胺和D-谷氨酸代谢、牛磺酸和亚牛磺酸代谢、精氨酸和脯氨酸的代谢、乙醛酸和二羧酸代谢以及谷胱甘肽代谢5条代谢通路。离母犊牛血清中具有抑菌作...     

Studies on the Mechanism of Diarrhoea Induced by Escherichia coli Heat-Stable Enterotoxin (STa) in Newborn Calves

Enterotoxigenic Escherichia coli (ETEC) produces a heat-stable enterotoxin (STa) that binds to and activates a putative intestinal receptor, guanylate cyclase, causing an increase in the intracellular levels of cyclic guanosine monophosphate (cGMP). Using flow cytometry and ¹²⁵I-STa binding assays, we studied the distribution of STa-receptors on enterocytes isolated from different segments of the newborn calf's intestinal tract. We also investigated the effect of STa on the intracellular levels of cGMP and ion transport to the intestinal lumen. More STa-receptors were found on enterocytes prepared from the ileum than on enterocytes obtained from the other segments of the intestinal tract. Guanylate cyclase activity was higher in the ileum of STa-challenged calves than in the ileum of control calves. No changes were observed in the guanylate cyclase activity of the other intestinal segments of the STa-challenged and control calves. Na⁺ levels, as measured by atomic absorption spectroscopy, were significantly increased in the luminal contents of the ileum of STa-challenged calves, whereas serum Cl^– levels were significantly lower in the STa-challenged calves than in control calves. This study supports previous observations on the role of guanylate cyclase in the initiation of STa-induced secretory diarrhoea and suggests that Na⁺/Cl^– coupling may be the major mechanism for the loss of ions in the diarrhoeal response that is mostly induced in the ileum of newborn calves.