Changes in serum pepsinogen and haemoglobin concentrations in calves infected with Haemonchus contortus

In four calves given Haemonchus contortus larvae, the serum pepsinogen concentration rose quickly to reach a mean of 3.5 iu tyrosine on day 14 after infection. The mean concentration dropped to 1.8 iu tyrosine by day 23 and remained around 2.0 iu tyrosine until an anthelmintic was given on day 57, when concentrations returned to preinfection values.     

Epidemiology and control of bovine ostertagiasis in South America

Gastrointestinal parasitism has been recognized by practitioners as the most common disease in beef cattle, mainly in weaning calves and fattening steers. Among the different genera, Ostertagia ostertagi is the predominant parasite in the temperate climate, in which the major beef and dairy cattle area of South America is situated. Outbreaks of Type I ostertagiasis are usually seen after weaning time (autumn-winter) when larvae counts are high and food availability is low. The development of the disease is rapidly established and 15-30 kg are lost in 30-50 days. Epidemiological studies have demonstrated a fast evolution of parasite eggs to larvae (L3) in summer (1 week or less), evolution being 30-45 days during winter. Inhibition O. ostertagi occurs during spring (September-December) and development resumes in late summer and early autumn. The production effect is seen as a significant reduction in body weight gain and occasionally clinical Type II ostertagiasis appears. A similar epidemiological pattern of inhibition of Ostertagia sp. has been recorded in Uruguay and temperate areas in southern Brazil.     

犊牛腹泻粪样中牛呼肠孤病毒的分离鉴定

通过在培养液中添加胰蛋白酶的方法,用MA104细胞从犊牛腹泻粪样中分离并鉴定了1株能稳定产生细胞病变(CPE)的牛呼肠孤病毒,命名为B-19株.RNA聚丙烯酰胺凝胶(PAGE)电泳可见呼肠孤病毒典型的10条核酸节段,呈3:3:4排列.电镜检测结果显示,病毒粒子呈典型呼肠孤病毒粒子形态,直径约70 nm;病毒L1基因保守区段RT-PCR检测及序列分析表明,扩增出的440 bp 目的片段符合预期大小,而且其核苷酸序列与GenBank参考毒株L1基因序列具有较高同源性;S1基因序列分析表明,B-19株属于呼肠孤病毒血清1型(ST1).     

A simple method for determination of pepsinogen in bovine serum and plasma.

Calf serum pepsinogen can be determined by radial diffusion in a casein-containiing agarose gel prepared at pH 8.2 and afterwards immersed in a BaGla-containing buffer, pH 2.4, whereby the casein is precipitated homogeneously. Serum samples are placed in wells in the gel, and at the low pH pepsinogen present in the samples will be activated and the casein digested, whereby transparent, circular zones are formed in the otherwise opaque gel. The diameter of these zones can be measured directly and used as an expression of the serum pepsinogen level. On analysis of a number of sera from calves with or without ostertagiasis a positive correlation was found between the results obtained by this method and conventional absorption photometry (r = 0.87, n = 55).     

Leukokinesis in bovine ostertagiasis: stimulation of leukocyte migration by Ostertagia

A blind-well chemotaxis chamber method was used to indicate migration stimulation of bovine neutrophil and eosinophil polymorphonuclear leukocytes and macrophages as related to ostertagiasis. Live exsheathed Ostertagia ostertagi 3rd-stage larvae (L3) and soluble L3 antigen (SLA), prepared by freeze thawing and sonic disruption of L3, enhanced cellular migration for eosinophils, but not for neutrophils and macrophages. Products of lymphocytes cultured with SLA for 3 to 6 hours were also examined, using lymphocytes from peripheral blood of helminth-free cattle and cattle infected with O ostertagi or Trichostrongylus axei. Lymphokines that enhanced cellular migration of neutrophils, eosinophils, and macrophages were present in culture supernatants of SLA-stimulated lymphocytes from O ostertagi-infected cattle, but not from cattle infected with T axei or helminth-free cattle. Seemingly, L3 and SLA were stimulants of eosinophil migration. Further, neutrophil, eosinophil, and macrophage migration was modulated by lymphokines produced by SLA-stimulated lymphocytes from cattle with ostertagiasis.     

Social isolation may influence responsiveness to infection with bovine herpesvirus 1 in veal calves

An experiment was performed to develop a model to study the impact of stress on responsiveness to infection with bovine herpesvirus 1 (BHV1) in veal calves. Social isolation after previous group-housing was used as a putatively stressful treatment. Group-housed specific pathogen-free veal calves (n=8) were experimentally infected with BHV1 at the age of 12 weeks. Half of the calves were socially isolated at the time of infection. Clinical, virological and serological responses to BHV1, and adreno-cortical reactivity to exogenous ACTH were examined. In comparison with group-housed calves, calves socially isolated at the time of infection showed a diminished clinical and fever response, and delayed viral excretion after primary infection with BHV1. Four weeks after social isolation, basal cortisol levels before, and the integrated cortisol response after administration of a low dose of ACTH, were significantly depressed in socially isolated calves. The results suggest that social isolation in veal calves influences the response to an experimental BHV1 infection. A possible mechanism is discussed.     

Characterization and identification of a bovine respiratory syncytial virus isolated from young calves.

Two identical viruses designated 371 and 375 were recovered from nasal secretions of 2 of 7 calves in a beef cow-calf herd in which calves (45 to 105 days of age) had signs of acute respiratory tract disease. The cytopathic, morphologic and physico-chemical characteristics of the isolates were those of bovine respiratory syncytial virus. Although a humoral antibody response to bovine respiratory syncytial virus was not observed, it was concluded that this virus probably had a part in the respiratory tract disease in these calves.     

The effects of late turnout on the epidemiology and control of ostertagiasis in calves

The main purpose of this experiment was to study the importance of time of turnout on the epidemiology and impact of ostertagiasis in calves pastured for the first time. When time of turnout onto permanent pasture was postponed from mid-May to mid-June, fewer overwintered larvae were picked up and re-contamination of pastures was markedly diminished. Consequently, the acquisition of loss-producing parasite burdens in the late part of the season was significantly reduced. Late turnout as a control strategy is discussed in relation to other preventive measures.     

Sequential isolation of rotavirus from individual calves

An outbreak of neonatal calf diarrhea was studied on a breeding farm of Japanese indigenous beef cattle. During the breeding season of 1982, 43 calves were born over the period 27 February-28 April. All but one of the calves suffered from neonatal diarrhea and 5 died. Bovine rotavirus was isolated in cell cultures from fecal specimens of 39 (90.7%) of the 43 calves during the outbreak, strongly suggesting that this was the causative agent; the virus was readily isolated from 81 (83.5%) of 97 specimens of diarrhea. Rotavirus was subsequently isolated from the feces of 7 of the calves in early May, more than one month after the initial virus isolation in early March. Two of these calves were again rotavirus-positive in early June, 41 days after the second virus isolation. Diarrhea had ceased in all 7 calves in March. Some antigenic differences were shown by the neutralization test between the early and later isolates from one of these calves, suggesting either re-infection with a serologically different virus, or persistent infection with the original virus following antigenic modulation.     

Colostral transfer of bovine immunoglobulin E and dynamics of serum IgE in calves

The role of IgE in protective immunity is becoming understood, therefore the colostral transfer of IgE and the age-dependent changes of IgE levels may be important for neonatal immunity. To investigate this question, serum samples were collected from range-fed Hereford cows and their calves from birth through 9 months of age. The sera were assayed for total IgE by enzyme-linked immunosorbent assay (ELISA). Calves were found to have significant levels of IgE during the first week postpartum, indicating colostral transfer of IgE. Thereafter, serum levels declined rapidly within 3 weeks from birth. The IgE levels began to increase after 12 weeks of age, and in some cases reached adult levels. The passive transfer of maternal IgE through colostrum may be important in providing early protection from disease, especially against intestinal parasites.     

Congenital spirochetosis in calves: association with epizootic bovine abortion

Congenital spirochetosis was encountered as a newly recognized infection of cattle. The spirochete was seen in blood of fetuses with lesions of epizootic bovine abortion. A spirochete with morphologic features similar to those found in the fetuses was detected in Ornithodoros coriaceus ticks. Ticks collected from rangelands were allowed to feed on cows that then produced epizootic bovine abortion-affected fetuses, and the fetuses had spirochetosis. Inapparent spirochetosis also was found in fetuses in clinically normal cattle sent to slaughter. Only a few lesions were seen in abattoir-collected fetuses. Fetal spirochetosis was common in the bovine population studied, and it appeared that infection may be limited only by the availability of the tick vector.     

Correlation between maternal serum antibodies and protection against bovine rotavirus diarrhea in calves

The correlation between maternal serum antibodies in beef calves at 2 days old and protection against diarrhea induced by natural bovine rotavirus (BRV) infection was examined. Virus neutralizing (VN) antibody titers against BRV in sera from calves that developed diarrhea by BRV infection within 14 days of age (BRV-diarrheal calves) were significantly lower than those from calves that had no diarrhea. In the BRV-diarrheal calves, a positive correlation was found between the VN antibody titers and age of the onset of diarrhea. There were negative correlations between the VN antibody titers and duration of the diarrhea, VN antibody titers and cumulative diarrhea scores, and the VN antibody titers and duration of virus shedding. These results suggest that the VN antibody titers against BRV in newborn calf serum could be an indicator of protection against BRV-induced diarrhea.     

Production and development of calves from sexed-bisected bovine embryos

Sixty-five chromosomal preparations from bisected bovine embryos were examined and 43 embryos (66.2%) with metaphase plates were observed; however, only 25 embryos (38.5%) were sexed. Fifteen of the bisected embryos sexed by chromosomal analysis were transferred to each of the 15 recipients, and 5 recipients became pregnant. Female calves were born on December 28, 1985, August 2, 1986 and July 18, 1988. The first female calf born from a sexed-bisected embryo (December 28, 1985) was the first case in Japan. The gestation lengths and birth weights of these calves were 277, 278 and 274 days, and 42.0, 44.0 and 37.0 kg, respectively. These two calves grew within the range of the "Standard developmental growth curve of the Holstein heifer" of the Japanese Holstein Association. The milk yield from 2 sexed-bisected cows were recorded. In the first cow (Case 1), she produced 8,575 kg of milk, 5.0% fat and 9.4% solids-non-fat (SNF) per year. In the other cow (Case 2), her expected milk volume was 7,800 kg per year. Confirmation of parentage was done by blood typing, and certified by the Japanese Livestock Animal Improvement Association.