Detection of Mycobacterium avium subsp paratuberculosis in formalin-fixed paraffin-embedded intestinal tissue by IS900 polymerase chain reaction

OBJECTIVES: To evaluate and compare methods for DNA extraction from formalin-fixed, paraffin-embedded tissues and methods for detection of Mycobacterium avium subsp paratuberculosis by IS900 PCR for confirmation of Johne's disease in ruminants. DESIGN: A laboratory study. PROCEDURE: Three methods of DNA extraction of differing complexity and two PCR protocols using different pairs of IS900 primers were compared. Sensitivity and specificity were assessed using samples from ruminants with and without histological evidence of Johne's disease. RESULTS: The simplest method of DNA extraction, which involved two cycles of boiling and freezing followed by centrifugation, gave more consistent results than two methods that required solvent extraction of paraffin, proteinase digestion and DNA purification. The sensitivity of detection of M avium subsp paratuberculosis in paraffin blocks stored for 1 to 6 years from 34 cases of Johne's disease in sheep, cattle and goats was 88% for a 229 bp IS900 PCR assay and 71% for a 413 bp assay, using the detection of acid-fast bacilli by Ziehl Neelsen staining of histological sections from the same blocks as the gold standard test. PCR results correlated with the abundance of acid-fast organisms in the tissues. No false positive reactions were detected. CONCLUSION: PCR for identification of M avium subsp paratuberculosis in formalin-fixed, paraffin-embedded intestinal tissues from ruminants is a rapid and useful method. A simple method of sample preparation is effective. Amplification of short fragments of IS900 is more effective than amplification of longer fragments.     

Comparative Parasitological and Haematological Changes in Two Breeds of Sheep Infected with Fasciola gigantica

Twelve each of Red Masai and Dorper sheep, aged between 6 and 9 months, were acquired from a Fasciola-free area of eastern Kenya. Each breed was divided into two groups of 6. The sheep in one group of each breed were experimentally infected with 400 viable metacercariae of Fasciola gigantica. The other group of 6 sheep of each breed remained as uninfected controls. The animals were monitored regularly for any evidence of disease. Blood samples taken weekly revealed a general reduction in red cell counts and packed cell volume, which was much faster in the infected Dorper sheep than in the Red Masai. This reduction started from the tenth week after infection and persisted to the end of the experiment 18 weeks post infection (PI). The absolute eosinophil counts rose in all the infected animals, but the values were higher among the Dorper than among the Red Masai. Patency occurred at weeks 12 and 13 PI in the Red Masai and Dorpers, respectively, with the latter shedding significantly more fluke eggs. The worm recovery rates were higher among the Dorpers than among the Red Masai, though not significantly so. On the basis of egg counts and clinicopathology, the Dorper sheep were considered to be more susceptible to F. gigantica infections.     

Some Observations on Endemic Fluorosis in Domestic Animals in Southern Rajasthan (India)

Chronic fluoride toxicity in the form of osteo-dental fluorosis was observed in cattle, buffaloes, sheep and goats from 21 villages of Banswara, Dungarpur and Udaipur districts of Southern Rajasthan where the mean fluoride concentration in drinking water varied from 1.5 to 4.0 ppm. The prevalence of dental fluorosis in calves (<1 year age) was greater than that in adult cattle and buffaloes. At a fluoride concentration in the water of 4.0 ppm, 100% of calves, 65.6% of buffaloes and 61.0% of cattle were found to be affected with dental fluorosis to varying degrees. In the older group of buffaloes, their teeth were brownish black instead of creamy yellow as found in calves and cattle. Out of 780 goats and 564 sheep, none revealed evidence of osteo-dental fluorosis. The overall prevalence of skeletal fluorosis was 8.5%, with the highest prevalence of 29.0% in cattle and 37.5% in buffaloes at a fluoride concentration of 3.2 ppm. None of the calves were affected with skeletal fluorosis. Intermittent lameness was observed in the older group of animals (>7 years age) at 2.8 ppm fluoride or more in the water. None of the fluorotic animals exhibited any apparent evidence of hypothyroidism, stunted growth or low milk production. There was no correlation between gender and the prevalence of fluorosis, but the prevalence and severity of skeletal fluorosis increased with increasing fluoride concentration and age. Possible factors causing variation in fluorosis in the cattle and buffaloes in villages with identical fluoride concentrations are discussed.     

Haemolytic Complement Activity and Humoral Immune Responses to Sheep Red Blood Cells in Indigenous Chickens and in Eight German Dahlem Red Chicken Lines with Different Combinations of Major Genes (dwarf,naked neck and frizzled) of Tropical Interest

A total of 376 chickens from different ecotypes were immunized with the non-pathogenic multi-determinant antigen sheep red blood cells (SRBC). The ecotypes included indigenous chickens from various locations in Tanzania (n=102), India (n=86) and Bolivia (n=89). In addition, eight German Dahlem Red (GDR) chicken lines with different major genes (dwarf, naked neck and frizzled) of tropical interest were also immunized with SRBC. Immune competence of the breeds was assessed by measuring complement haemolytic activity, both from the classical calcium-dependent complement pathway (CPW) and alternative calcium-independent complement pathway (APW), alongside IgTotal, IgG and IgM antibody responses to SRBC at 7 days post immunization. Large variations in complement activity and antibody responses to SRBC were observed within and between the indigenous breeds. Many indigenous chickens, especially from Bolivia, showed decreased complement activity (APW) following immunization with SRBC. Breeds from India showed the highest CPW activity and humoral (especially IgM) responses to SRBC, suggesting high immune competence. In contrast, Bolivian chickens were characterized by low CPW activity, low APW activity and low antibody levels to SRBC suggesting an overall low immune competence. In the GDR chickens, characterized by high CPW activity and high IgG antibody responses to SRBC, the major genes for naked neck, frizzling and dwarfism had no significant effect on the antibody responses and complement activity to SRBC.     

Pharmacokinetics of enrofloxacin in lactating sheep

The pharmacokinetics of enrofloxacin (ENR) was investigated after its intravenous (iv) and intramuscular (im) administration in six healthy lactating sheep. After iv ENR injection (as a bolus), the elimination half-life (t(1/2beta)), the volume of distribution (Vd(area)), and the area under the concentration vs. time curve (AUC) were 3.30 (0.36)h, 2.91 (0.17)l/kg and 4.19 (0.18) microg h/ml, respectively. The maximum milk concentrations of ENR (C(max)), the area under the milk concentration vs. time curve (AUC(milk)) and the ratio AUC(milk)/AUC(serum) were 2.38 (0.14)microg/ml, 23.76 (2.21) microg h/ml and 5.62 (0.30), respectively. After im administration of ENR the t(1/2beta), C(max), time of C(max) (t(max)) and absolute bioavailability (F(abs)) were 3.87 (0.10)h, 0.74 (0.07) microg/ml, 0.83 (0.12)h and 75.35%, respectively. The C(max), AUC(milk) and the ratio AUC(milk)/AUC(serum) were 1.94 (0.13) microg/ml, 24.81 (2.25) microg h/ml and 8.15 (0.96), respectively.     

Diversity of Mannheimia haemolytica and Pasteurella trehalosi Serotypes from Apparently Healthy Sheep and Abattoir Specimens in the Highlands of Wollo,North East Ethiopia

The prevalence and serotypic diversity of Mannheimia [Pasteurella] haemolytica and Pasteurella trehalosi from nasal swabs, sera and abattoir specimens from sheep in the highlands of Wollo, North East Ethiopia was investigated. Prevalence rates of 83% and 75% of these microorganisms were found in the serum samples and nasal swabs, respectively, from apparently healthy sheep. In a local abattoir, 205 lungs were investigated, 34% of which showed pneumonia, from which samples were collected from 51 lungs and the same number of corresponding tonsils. Mannheimia and Pasteurella species were isolated from 59% of these pneumonic lungs and 69% of the respective tonsils. M. haemolytica serotypes accounted for 41 (59%) and P. trehalosi for 11 (32%) of the isolates from the abattoir specimens. The majority (67%) of isolates from nasal swabs were P. trehalosi, M. haemolytica being isolated f rom 4 (13%) of the swabs. M. glucosida was isolated only from the tonsils. The predominant serotypes of the isolates from both the nasal swabs and the abattoir specimens were M. haemolytica A1 (17%) and P. trehalosi T4 (16%) and T3 (13%). P. trehalosi T15 was less commonly encountered, while M. haemolytica A9 and A13 were not isolated. Studies on sera from 100 sheep indicated that antibodies against M. haemolytica serotype A1 (14%) were most common, followed by A5 and A8 (each 10%) and A9 and P. trehalosi T3 (each 9%) and T4 (8%). Antibodies against M. glucosida or serotype A11 occurred in 2% of the sera. Multiple serotypes were common in all types of samples. The importance of including in vaccines the most prevalent serotypes involved in the pneumonia of sheep in the area is discussed.     

复合型生化秸秆颗粒饲料育肥成年滩羊效果试验

利用氨-碱-盐化和微生物技术复合处理作物秸秆,再配合工业副产品、精料及矿物质、维生素添加剂等制成颗粒饲料,饲喂成年滩羊,观察育肥效果。试验结果表明：试验组(复合处理秸秆)与对照组(未处理秸秆)相比,日增重提高25．06％,饲料报酬提高25．23％,屠宰率提高5．11％,净肉率提高7．71％,试验期内平均每只育肥羊多获利润13．13元。     

Risk factors for mortality associated with respiratory disease among Menz and Horro sheep in Ethiopia

A retrospective case-control study was conducted on 6718 sheep of two breeds (2772 Horro and 3946 Menz) on risk factors for mortality associated with respiratory disease (MARD) in Ethiopia, based on data collected between October 1993 and December 1997. Potential risk factors examined were breed, gender, age, month, and air temperatures.Fifty-four per cent of total deaths in the flock could be attributed to respiratory disease and the annual MARD rate ranged between 6.3 and 19.0%. There was significant breed (P<0.0001) and gender (P<0.0001) difference in MARD. The Horro breed had a higher (P<0.0001) annual MARD than the Menz breed (16.5+/-0.18 vs. 12.4+/-0.15%). A higher (P<0.0001) proportion of males suffered than females (15.1+/-0.23% vs. 13.8+/-0.13%). Age was also an important risk factor for MARD: there was a strong polynomial relationship (R(2)=0.91, P<0.0001) between MARD and age; the risk of being young if a sheep was a MARD case was high. MARD was high between October and March but relatively low between the months of April and September. There was a significant (P<0.05) negative cubic relationship (R(2)=0.49) between monthly MARD and monthly average minimum air temperatures. There was also a significant (P<0.01) positive exponential relationship (R(2)=0.61) between monthly MARD and average monthly daily deviation between maximum and minimum air temperatures.Timely health and management interventions focusing on these factors are necessary to alleviate losses from MARD. Understanding variations in MARD risk within a population can enhance early response to potential outbreaks, reducing losses.     

绵羊Inverdale基因(FecX~I)研究进展

Inverdale基因 (FecXI)是位于X染色体上影响绵羊排卵数的一个主效基因。本文简要介绍了FecXI 基因的发现、来源、内分泌学、产业化利用以及Inverdale母羊的卵巢特性 ,并对FecXI 基因的前景进行了讨论。