Optimal fecal assessment

Fecal testing is a common component of most gastrointestinal work-ups. A multitude of diagnostic techniques are available for identifying parasites and pathogens, or showing abnormalities of flora. Optimal fecal assessment involves careful formulation of a differential list based on signalment, history, and clinical signs. Tests should be selected and interpreted based on their relative sensitivity and specificity for specific conditions. It is essential to use effective testing methods for the etiologies of concern. This article reviews the plethora of diagnostic techniques available for fecal assessment. Indications, limitations, and issues of specimen handling for each technique are discussed. The optimal approach to the diagnosis of some common parasites, pathogens, abnormalities of flora, and metabolic conditions are covered.     

Ovine Paratuberculosis: Seroprevalence and comparison of fecal culture and direct fecal PCR assay

Johne’s disease is chronic, incurable disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP). Most studies in Egypt focused on incidence of the disease in cattle but few studies were reported presence of antibodies against MAP in sheep. The present study determined the seroprevalence rate of MAP among sheep in four Governorates and assessed the associated risk factors to MAP-infection. The seroprevalence rate of MAP among sheep was non-significant varied between different Governorates, it was ranged between 3.75%–12.3%. The results revealed that the seroprevalence rate of the disease was significantly increased in diarrheic sheep (11 %, 95 %CI: 7.2−16.2) during spring (15 %, 95 %CI: 8.3−25) and summer (8%, 95 %CI: 4.13−13.8) seasons. Contrary, the age of sheep and contact with other ruminants like cattle or goats had non-significant effect of spreading of MAP-infection among sheep. The detection of MAP in feces of sheep was carried out using culture and PCR to determine the efficiency of both tests. The kappa test revealed good agreement between both tests for detection of MAP. The obtained finding confirms the presence of MAP among sheep in Egypt. So, the appropriate control measures should be taken to reduce spreading of the disease among sheep and reduce its economic losses.     

Development of a fecal sample collection strategy for extraction and quantification of fecal immunoglobulin A in dogs

OBJECTIVE: To develop a fecal sample collection strategy and quantification method for measurement of fecal IgA concentrations in dogs. SAMPLE POPULATION: Fecal samples from 23 healthy pet dogs of various breeds. PROCEDURES: Immunoglobulin A was extracted from fecal samples. An ELISA for the measurement of fecal IgA concentrations was established and analytically validated. Intraindividual variation of fecal IgA was determined by calculation of coefficients of variation. A sample collection strategy was developed on the basis of results of intraindividual variation of fecal IgA concentrations. A reference range for fecal IgA concentrations was determined. RESULTS: The method for extraction and quantification of fecal IgA was determined to be sufficiently sensitive, reproducible, accurate, and precise. On the basis of the intraindividual variability of our results, the determined fecal sample collection strategy required analysis of a total of 4 fecal samples/dog, with each fecal sample collected on 2 consecutive days with 28 days between sample collection periods (ie, days 1 and 2 followed by days 28 and 29). Reference range values for fecal IgA concentration were 0.22 to 3.24 mg/g of feces. CONCLUSIONS AND CLINICAL RELEVANCE: Methods of fecal IgA extraction and quantification used in our study allow for identification of dogs with consistently low fecal IgA concentrations. Use of these techniques will enable future investigations into possible associations between low fecal IgA concentrations and signs of gastrointestinal disease in dogs.     

Comparison of fecal crude protein and fecal near-infrared reflectance spectroscopy to predict digestibility of fresh grass consumed by sheep

Organic matter digestibility (OMD), an essential criterion for the evaluation of the nutrition of ruminants, cannot be measured easily at pasture. Therefore, the objective of this study was to test and compare 2 methods of OMD prediction based on the fecal CP content (CPf) or near infrared reflectance spectroscopy (NIRS) applied to feces. First, published equations derived from fecal N (Eq. 1(CP), n = 40) and from fecal NIRS (Eq. 1(NIRS), n = 84) were used to predict OMD of an independent validation data set from which in vivo OMD, ranging from 58 to 74%, was measured for 4 regrowth stages of Digitaria decumbens. Second, to establish equations usable in grazing situations and to improve the efficiency of the predictions, new equations were calculated from a large data set (n = 174) using CPf (Eq. 2(CP)) or fecal NIRS (Eq. 2(NIRS)). By applying the CPf method, Eq. 2(CPf) (OMD, % = 88.4 - 263.9/CPf, % of OM; residual SD = 2.92, r(2) = 0.63) showed similar statistical parameters (P < 0.01) when compared with Eq. 1(CP) (OMD, % = 86.6 - 266.2/CPf, % of OM; residual SD = 2.95, r(2) = 0.79). When using fecal NIRS, Eq. 2(NIRS) showed decreased SE of calibration (SEC = 1.48) and of cross-validation (SECV = 1.75) and greater coefficient of determination of cross-validation (R(2)(CV) = 0.85) than the previously published Eq. 1(NIRS) (SEC = 1.78, SECV = 2.02, R(2)(CV) = 0.77). The validation of the 4 equations on the validation data set was satisfactory overall with an average difference between the predicted and the observed OMD ranging from 0.98 to 2.79 percentage units. The Eq. 2(NIRS) was nevertheless the most precise with a decreased residual SD of 2.53 and also the most accurate, because the SD of the average difference between predicted and observed OMD was the lowest. Therefore, fecal NIRS provided the most reliable estimates of OMD and is thus a useful tool to predict OMD at pasture. However, an adequate number of reference data are required to establish good calibration. Indeed, better calibration statistics were obtained by increasing the data set from 84 (Eq. 1(NIRS)) to 174 (Eq. 2(NIRS)). In contrast, using fecal N on a set of 84 or 174 points did not improve the prediction. Both methods are useful for predicting OMD at pasture in certain circumstances, using fecal NIRS when a large data set (n = 84 and n = 174) is available and fecal CP with smaller data sets (n = 40).     

Lack of evidence for fecal shedding of Mycobacterium avium subsp. paratuberculosis in calves born to fecal culture positive dams

The objective was to detect presence of calves excreting Mycobacterium avium subsp. paratuberculosis (MAP) in their feces as a consequence of being born to MAP fecal culture positive (vs. negative) dams. For each cow that was about to calf, approximately 10 g of feces was collected manually by the herdsmen from the rectum using a disposable plastic examination sleeve within 48–72 h prior to actual calving. Between 1 and 3 d of birth, herd personnel collected approximately 10 g of fecal samples followed by monthly visits to the farm at which time 10 g of fecal samples were again collected by study investigators from each calf at approximately 30, 60 and 90 d of age. Mycobacterium avium subsp. paratuberculosis was recovered from 8% (5/60) of the cows that gave birth to calves. However, MAP was not recovered from any of the fecal samples (0/240) collected from study calves. Findings of the present study suggest lack of evidence for fecal excretion of MAP in calves born to fecal culture positive (vs. negative) dams in a heavily infected herd.     

猪粪样DNA提取方法的比较

哺乳动物胃肠道中存在约30个属500多种不同的细菌,约1×1014个活细菌,其形成了复杂而动态平衡的微生态系统,对宿主营养物质的消化、吸收及免疫机制激活等起着十分重要的作用[1].这微生态平衡失调,机体正常的生理功能就会发生紊乱,导致疾病的发生、流行,对畜牧养殖业尤其是规模化养殖等带来极大的潜在威胁.因而,近年来对胃肠道微生物区系结构及其多样性研究成为热点,但由于胃肠道的特殊生存环境,目前有60%～80%的微生物是无法用传统的分离培养技术进行研究, 从而阻碍了人们对胃肠道微生物结构及其多样性的客观认识.     

Comparison of methods for assay of fecal proteolytic activity

Fecal proteolytic activity (FPA) in ten normal dogs was readily detected either calorimetrically using azocasein substrate or by radial enzyme diffusion into agar gels containing casein substrate. Daily FPA ranged from 17 to 207 azocasein units/g (ACUIG) or 4 to 18 mm of casein hydrolysis, while mean 3-day FPA ranged from 58 to 10 1 ACUIG or 7 to 15 mm. Studies of proteolytic activity remaining after treatment of fecal extracts with a specific trypsin inhibitor indicated that trypsin accounted for 0% to 71% of proteolytic activity. Proteolytic activity decreased steadily in fecal specimens stored at room temperature or above, but there was only slight loss in activity during storage for up to 5 days at 4 degrees C. Proteolytic activity was unaffected by repeated freezing and thawing and samples could be stored for long periods at -2 degrees C without noticeable loss of activity. It is concluded that assays of FPA using either azoprotein substrate or radial enzyme diffusion into agar gels containing casein substrate allow evaluation of exocrine pancreatic function in dogs, provided that several samples are tested. These methods are suitable for application in a variety of species.     

Comparison of models estimating digesta kinetics and fecal output in cattle from fecal concentrations of single-dosed markers of particles and solutes.

Fecal concentrations of chromium and cobalt, following a single labeling dose of Cr-mordanted fiber and Co-EDTA to the rumen, were obtained from two experiments: one with beef cows fed two diets before and after parturition, and one with growing bull calves fed two diets of high and low fill volume. These data were used to compare three optional models that estimated the whole digestive tract kinetics of particles and solutes and fecal output, with a fourth model that estimated particle kinetics only. The first model (M1) assumes separate routes for particles and solutes, with two bypass fluxes (i.e., simultaneous fluxes from one pool to more than one other pool) in the particle route and one in the solute route. The second model (M2) is similar to M1, but allowance is made for some of the particles to pass to the solute route. The third model (M3) assumes that most of the kinetic variables in the solute route are identical to the correspondent variables in the particle route. The fourth model (M4) assumes an unspecified number of sequential compartments with constant increase of the outflow rate from each compartment to the next one, without allowance for any bypass fluxes. All the models could fit all the data sets. Goodness of fit was the best with M2 and the worst with M3. Goodness of fit of the particle curve with M2 was comparable to that of M4. Model M1 estimated the shortest and M3 estimated the longest total retention time (TRT) for particles (72.8, 85.0, and 91.2 h for M1, M2, and M3, respectively), and the partition of retention time between the different pools differed among models. There were no significant differences among models in their estimates of solute TRT (30.2, 31.5, and 30.8 h for M1, M2, and M3, respectively). Fecal output estimations were similar among models, all of them overestimating the predetermined measurements by 9.5 to 13%. The r2 of the linear regression of the estimated on the determined fecal output was .74, .75, and .70 for M1, M2, and M3, respectively.     

Inhibitory effect of different enterocins against fecal bacterial isolates

Anti-microbial activity of five different enterocins produced by ruminal and environmental enterococci against fecal bacterial isolates was tested. The majority of all 61 strains (80.4%) were inhibited by all enterocins used. The remaining strains were inhibited at least by one enterocin. The highest activity, 51,200 arbitrary units per ml-1 (AU ml-1) was measured when crude extracts of enterocin V24 (CE V24) were used against enterococci. CE AL41 and EK13 showed an activity of 25,600 AU ml-1. The lowest activity was obtained with Enterocin CE EC24 (100-400 AU ml-1). Crude extract of enterocin CCM4231 inhibited the indicator strains with an activity ranging from 100 up to 6400 AU ml-1, which is in accordance with our previous results. It further indicates the probable use of enterocins or its producers in environmental biotechnology with the aim to increase the effectiveness of sanitation of animal excrements after standard treatment.     

Daily variability of equine fecal strongyle egg counts.

Fecal egg counts often are used for diagnosing equine strongyle infections and estimating the number of eggs shed in the feces. An individual egg count should be interpreted in view of the normal fluctuation of egg numbers in an individual horse. In this study, the daily variability of strongyle fecal egg counts from horses was investigated. The Cornell-McMaster egg-counting technique was used to estimate the eggs per gram of feces in repeated daily fecal samples from 39 horses. The variation of the daily egg counts across 4 days was greater than would be expected if a consistent number of eggs were produced and dispersed randomly in the feces. The means and variances of the daily counts from each horse had a logarithmic relationship. For practical purposes, however, the fluctuation of egg counts is low enough for the fecal egg count to be used to identify horses for treatment, to estimate pasture contamination, or to assess response to therapy.     

Persistent fecal Salmonella shedding in five dairy herds

OBJECTIVE: To monitor patterns of Salmonella fecal shedding in naturally infected dairy herds, determine the association between fecal shedding and individual animal production measures, and evaluate potential risk factors for shedding of Salmonella organisms among cattle in dairy herds. DESIGN: Longitudinal study. SAMPLE POPULATION: 5 Ohio dairy herds. PROCEDURE: For 3 herds, fecal samples were collected from all mature cows and unweaned calves 7 times during an 18-month period. For the remaining 2 herds, fecal samples were collected from 50 lactating cows 6 times during a 12-month period. Individual animal production records for 3 herds were used to examine associations between individual fecal Salmonella shedding status and 305-day mature-equivalent milk production, somatic cell count, milk fat content, and milk protein content. Multivariable logistic regression was used to test for associations between fecal shedding status and breed, lactation status, lactation number, and duration of lactation. RESULTS: None of the adult animals had clinical signs of salmonellosis, but prevalence of fecal Salmonella shedding at individual collection times ranged from 0 to 99% for cows and from 0 to 67% for unweaned calves. Mature cows were more likely to be shedding Salmonella organisms than were unweaned calves. Within herds, lactation status and duration of lactation for individual animals were associated with Salmonella shedding status. Salmonella fecal shedding status was not associated with individual cow production measures. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that subclinical fecal Salmonella shedding can persist in dairy herds for up to 18 months with no measurable effects on health or production of individual cows.     

动物粪便沙门菌PCR检测技术的研究

为了建立一种动物粪便样品中快速、特异、敏感的沙门菌检测方法,根据沙门菌肠毒素stn基因设计一对引物,对不同血清型的沙门菌和非沙门菌进行PCR检测,并对该PCR方法进行反应的灵敏度、模拟粪便样品的最低检出限测定及粪便样品的检测。运用该方法对250份粪便样品进行检测,同时用传统方法进行验证。结果表明,设计的引物特异性好,能专一性扩增出约260 bp条带;该引物灵敏度高,能进行有效检测的核酸最低起始量为43.85 pg,纯菌检测灵敏度达1 cfu/mL。接种沙门菌到粪便样品中,当粪便样本中菌量达103cfu/mL以上时,不需要增菌,沙门菌可立即检出,增菌后检出限可以达到1 cfu/mL。PCR检测250份样品共检出18份阳性,同时传统细菌培养方法证明结果正确。该方法可用于粪便样品的检测。