Hormonal induction of lactation in nonpregnant ewes

Exogenous hormone treatments designed to induce nonpregnant ewes to lactate at levels sufficient to rear orphan lambs were investigated in three breeds (Blackface, Dorset and Greyface) and in a total of 14 groups. The hormone treatments consisted of an induction phase lasting 1–6 weeks during which most ewes received daily subcutaneous injections of 75 mg of progesterone and 100 µg of oestradiol-17β and a trigger phase lasting 1 or 2 weeks during which 5 mg of oestradiol-17β and/or 10 mg of dexamethasone were given daily and the daily dose of progesterone was reduced to zero. From the end of the trigger phase for at least 2 weeks, milk production was determined three times daily by hand milking after prior intravenous injections of 5 IU of oxytocin. The linear dimensions of the udder were measured in each ewe at 5–6 day intervals throughout the induction and trigger phases.

Udder sizes increased in response to hormone treatment in all cases, and the rate of increase was usually 1.75–11.3 times greater during the trigger phase than during the induction phase. Accumulation of milk in the udder during the trigger phase resulted in mean milk yields of 212–763 ml on the first day of milking, which were higher than the mean yields of 130–354 ml on the second day. Thereafter the mean daily milk yields increased progressively to reach 579–1301 ml after 14 days of milking. Group comparisons revealed the following: an induction phase of at least 4 weeks duration was required to ensure that all hormone-treated ewes produced 800 ml or more of milk/day by 14 days of milking; during the trigger phase, oestadiol-17β alone was a more effective lactogenic agent than dexamethasone alone, and dexamethasone apparently hindered the lactogenic actions of oestradiol-17β when both hormones were given together; extending the duration of the trigger phase from 1 to 2 weeks did not improve subsequent milk yields; and there were no significant breed differences in milk yield responses to similar hormone treatments.

It is concluded that a 4–6 week induction phase followed by a l-week trigger phase using the progesterone and oestradiol-17β doses noted above but excluding dexamethasone would induce in most nonpregnant ewes lactation at levels sufficient to rear orphan lambs. Compared to the compositions of normal colostrum and milk, the milk from some of the present ewes had lower dry matter contents, fat concentrations and immunoglobulin-G concentrations and generally similar lactose concentrations. These differences were not considered to be sufficient to jeopardise the survival of lambs reared by such ewes.     

Evaluation of Abattoir Inspection for the Diagnosis of Mycobacterium bovis Infection in Cattle at Addis Ababa Abattoir

Detailed postmortem examinations were conducted to evaluate the efficiency of meat inspection procedures and to determine the distribution of lesions in Mycobacterium bovis-infected cattle. The study involved routine inspection at slaughter, collection of tissues for detailed examination in the laboratory, and bacteriological examination to identify M. bovis. Additionally, a 10-year (1992--2001) meat inspection record was analysed to determine tuberculosis trends in the past decade. chi2-Test and simple regression were used to analyse the data. Out of 1350 cattle examined, 1.5% were found with tuberculous lesions. Routine abattoir inspection detected only 55% of cattle with confirmed lesions. Fifty-four per cent of tuberculous lesions were found in the lungs and thoracic lymph nodes, 23% in the lymph nodes of the head, and the remaining 23% in the mesenteric and other lymph nodes of the carcase. M. bovis was additionally isolated from an animal that had no gross lesions of tuberculosis. On average, the annual rate of whole-carcase condemnation due to generalized tuberculosis was 0.024% and it has increased annually by 0.34% over the past decade. The rate of whole-carcase condemnation indicates a high degree of TB transmission and requires immediate attention from both the economic and public health points of view. The lower sensitivity of routine abattoir inspection confirms the importance of improving necropsy procedures.     

microRNAs作为结核分枝杆菌感染标志物的研究进展

微小RNA(microRN.As)是一类长度约为22个核苷酸的非编码单链RNA分子,它参与基因转录后的表达调控,在免疫系统的调控和运行中具有重要作用。结核分枝杆菌是典型的胞内寄生菌,其感染能够引起人畜共患结核病。从microRNAs与结核免疫机制的相关性以及在结核分枝杆菌感染过程中巨噬细胞、外周血单核细胞及血清中microRNAs表达谱变化等方面,进行综述microRNAs作为结核分枝杆菌感染标志物的研究现状,以期为动物结核病检测提供理论参考。     

Study on Optimization of the Conditions of Detecting Mycobacterium tuberculosis in Milk by Technique of Loop-mediated Isothermal Amplification

To optimize the loop-mediated isothermal amplification (LAMP) method to detect Mycobacterium tuberculosis in milk,the highly conservative 16S rRNA gene of Mycobacterium tuberculosis was selected as a target to design specific primers.Compared the modified method of CATB/NaCl,bacterial genome DNA extraction kit and thermal cracking method to extract the DNA of Mycobacterium tuberculosis,the best approach was chosen.Mycobacterium tuberculosis suspension liquid was diluted with sterilization milk to confirm the susceptibility of this assay.And then Brucella,Escherichia coli,Staphylococcus aureus,Listeria monocytogenes,Bacillus pasteurii and Salmonella were used for specificity detection.The results showed that the modified method of CATB/NaCl was better than the others.The sensitivity of LAMP was 3×10⁰ CFU/mL,and the specificity was 100%.The sensitivity of detecting Mycobacterium tuberculosis in milk by LAMP was 3×10¹ CFU/mL.     

Strategy for the detection and differentiation of Mycobacterium avium species in isolates and heavily infected tissues

The members of Mycobacterium avium species, comprising M. avium subsp. paratuberculosis, M. a. hominissuis, M. a. avium, M. a. silvaticum, are currently the most prevalent opportunistic pathogenic mycobacteria causing mycobacterial infection in animals and humans. The ability to distinguish between these subspecies is of relevance for proper diagnosis and control programmes of the diseases. The aim of this study was to design a fast and specific PCR strategy for the detection and differentiation of M. avium subspecies from the solid plate cultures for use in routine veterinary diagnosis. We have developed a multiplex PCR based on IS900, IS901, IS1245 and the dnaJ gene. This method allows the detection of M. a. paratuberculosis, M. a. hominissuis and M. a. avium/M. a. silvaticum in one PCR reaction and theoretically enables mixed infections of M. a. paratuberculosis and M. a. avium or M. a. paratuberculosis and M. a. hominissuis to be revealed. The sensitivity of this multiplex PCR is 10(3)CFU for each bacterial strain in one PCR reaction, which also enabled the use of this test directly for DNA isolated from the tissue of the heavily infected sheep.     

Improving protective efficacy of BCG vaccination for wildlife against bovine tuberculosis

Possums are a wildlife vector of bovine tuberculosis in New Zealand. Vaccination of possums with BCG is being considered as a measure to control the spread of bovine tuberculosis to cattle and deer. Delivery via oral bait is feasible but BCG is degraded in the stomach. The aim was to determine whether ranitidine (Zantac) would reduce gastric acidity and enhance the efficacy of intragastrically administered BCG. A dose of 75 mg reduced gastric acidity for at least 4 h. Thus, possums were vaccinated intragastrically with BCG after receiving 75 mg ranitidine or ranitidine or BCG alone, as controls, before challenge with virulent Mycobacterium bovis. Proliferative responses of blood lymphocytes to M. bovis antigens after vaccination were significantly higher in possums given ranitidine/BCG compared to controls and seven weeks after challenge they had significantly lower lung weights and spleen bacterial counts than ranitidine alone controls. Vaccination with BCG alone only gave a reduction in loss in body weight. Agents that reduce gastric acidity may be useful in formulating BCG for oral bait delivery to wildlife for vaccination against bovine tuberculosis.     

Prevalence of bovine tuberculosis and animal level risk factors for indigenous cattle under different grazing strategies in the livestock/wildlife interface areas of Zambia

A cross-sectional study was conducted to investigate the prevalence and animal level risk factors for bovine tuberculosis (BTB) in indigenous cattle of the livestock/wildlife interface areas in Zambia. A total of 944 cattle from 111 herds were investigated. The comparative intradermal tuberculin test (CIDT) was used to identify reactor animals for BTB. Animal level data on sex, age, parity and body condition score were registered. The overall animal prevalence of BTB as determined by the CIDT was 6.8% (95% CI: 4.2, 9.5%). In Lochinvar and Blue Lagoon areas, animal level prevalence were observed at 5.2% (95% CI: 2.2, 8.2%) and 9.6% (95% CI: 6.1, 13.2%), respectively. Kazungula, an area outside the livestock/wildlife interface, had a prevalence of only 0.8% (95% CI: 0.0, 2.3%). The age of the animal, its body condition score and the type of management system, were predictive of its BTB status. The study revealed that BTB was relatively high in the livestock/wildlife interface areas of Lochinvar and Blue Lagoon compared to Kazungula. These findings should raise a serious public health concern considering the extent to which the communities of the study areas are in contact with their animals and the levels at which they use untreated milk.     

Responses to tuberculin among Zebu cattle in the transhumance regions of Karamoja and Nakasongola district of Uganda

Responses to tuberculin in Zebu cattle of the transhumant pastoral farming system in Karamoja region and Nakasongola district in the north-eastern and mid-central regions in Uganda, respectively, were investigated using a comparative intradermal tuberculin skin test. Of the 1864 cattle tested from 30 large units (superherds) in Karamoja and 7 herds in Nakasongola, a total of 28 animals from 19 herds (51.4%) tested positive. Inter-district tuberculin reactor prevalence variations seemed to be influenced by climate, with impact on both the management patterns and transmissibility of agent. High herd tuberculin reactor prevalence (51.4%) was attributed to widespread contacts and mixing of animals between herds. Low individual animal tuberculin test positivity (mean = 1.4%) was attributed to low transmissibility of the agent under the Karamoja climate, which is semi-arid, and to increased resistance due to non-specific response to environmental mycobacteria and natural selection, since there was no active control against bovine tuberculosis. Owing to similarities in management practices in Karamoja and widespread risk factors, it was difficult to identify which were more important, but variations in sources of drinking water pointed to provision of lake and borehole water during dry season as reducing the risk. Positive bovine tuberculin reactor prevalence and skin reactor status were related to age.     

基于iTRAQ定量蛋白质组学技术的不同感染状态结核病牛血清蛋白质组学分析

为了探明不同感染状态结核病牛血清蛋白质水平的差异,揭示结核病牛在不同感染状态下的生理状态.本研究通过皮内变态反应、IFN-γ释放试验从临床筛选结核病阳性牛(TB)和阴性牛(NC),根据牛鼻拭子巢式PCR检测结果将临床阳性牛(TB)分为PCR阳性结核病牛(TBP)和PCR阴性结核病牛(TBN),每组20头,采集血清.应用...     

牛结核病诊断方法研究进展

牛结核病主要是由牛分支杆菌引起的一种人兽共患传染病,近年来发病率有所上升,给奶牛养殖业造成了巨大的危害。目前,牛结核病的诊断仍然以传统的迟发性变态反应试验为主,其他诊断方法有根据临床症状和病理变化诊断、抗酸染色法、细菌分离培养法、PCR法、血清学方法、淋巴细胞转化试验、γ-干扰素试验和菌体成分检测法等。为了净化该病,必须提高诊断方法的敏感性和特异性。文章对这些诊断方法及其优缺点做了概述,并指出结核病普查检测时,比较合理的诊断方式是迟发性变态反应试验和间接ELISA法同时运用。