Employing a Monte Carlo algorithm in expectation maximization restricted maximum likelihood estimation of the linear mixed model

Multiple‐trait and random regression models have multiplied the number of equations needed for the estimation of variance components. To avoid inversion or decomposition of a large coefficient matrix, we propose estimation of variance components by Monte Carlo expectation maximization restricted maximum likelihood (MC EM REML) for multiple‐trait linear mixed models. Implementation is based on full‐model sampling for calculating the prediction error variances required for EM REML. Performance of the analytical and the MC EM REML algorithm was compared using a simulated and a field data set. For field data, results from both algorithms corresponded well even with one MC sample within an MC EM REML round. The magnitude of the standard errors of estimated prediction error variances depended on the formula used to calculate them and on the MC sample size within an MC EM REML round. Sampling variation in MC EM REML did not impair the convergence behaviour of the solutions compared with analytical EM REML analysis. A convergence criterion that takes into account the sampling variation was developed to monitor convergence for the MC EM REML algorithm. For the field data set, MC EM REML proved far superior to analytical EM REML both in computing time and in memory need.     

Recovery threshold of Toxocara canis eggs from soil

The purpose of this study was to evaluate the threshold of Toxocara canis eggs form soil samples through utilisation of a centrifuge-flotation technique (CFT). Aliquots of soil (1 g each) were artificially contaminated with known numbers of T. canis eggs (1, 10, 25, 50, 100, and 200 eggs). The threshold was evaluated based on a CFT using zinc sulphate (Zn₂SO₄) and sodium nitrate (Na₂NO₃) solutions at a specific gravity of 1.20. The number of eggs recovered was directly proportional to the number of eggs employed to seed the soil. Both solutions enabled full recovery of samples containing merely three eggs; only Zn₂SO₄ demonstrated efficiency in soil contaminated with a single egg. A recovery rate of 100% was obtained for all tests with samples containing 10 and 25 eggs for Zn₂SO₄ and Na₂NO₃, respectively_. There was no difference in the mean number of recovered eggs regarding either the efficacy of the solutions or the repetition of evaluations in the same trial (p > 0.05). Therefore, the CFT is efficient for the detection of Toxocara eggs, even in samples containing low egg numbers.     

Rumen-protected choline administration to transition cows: effects on milk production and vitamin E status

We investigated the influence of rumen-protected choline (RPC) supplementation on milk production, lipid metabolism and vitamin E status in dairy cows receiving a silage-based diet. Twenty-six Italian Holstein multiparous cows were assigned by weight and average production in the previous lactation, to one of two groups: control (no RPC supplementation) and RPC (supplemented with 20 g/day rumen-protected choline chloride). Treatment began 14 days before expected calving and continued for 30 days after parturition. Choline administration significantly increased milk production during the first month of lactation and also the concentration (and total secretion) of choline in milk, but did not affect fat or protein concentrations in milk, or plasma levels of glucose, beta-hydroxybutyrate, cholesterol and non-esterified fatty acids (NEFA). However, around parturition, NEFA concentrations in plasma were lower in treated animals than in controls, suggesting improved lipid metabolism as a result of choline supplementation. Choline supplementation also increased alpha-tocopherol plasma concentrations, suggesting a novel aspect in dairy cows.     

Ultrasonographic evaluation of urinary bladder in normal,fern fed and enzootic bovine haematuria-affected cattle

A total of 19 adult hill cattle of both sexes were subjected to trans-rectal ultrasound scanning of urinary bladder to evaluate bladder wall thickness and the presence of space-occupying lesions. The animals were divided into four groups. Eight apparently healthy hill cattle maintained under standard ration served as control (group I) and the remaining II animals were divided into three groups (II, III and IV). Group II animals (n = 8) were fed with different type of ferns which were further divided into subgroups II-P, -D and -B and fed with Polystichum squarrosom (n = 2). Dryopteris juxtaposita (n = 2) and Pteridium aquilinum (n = 4) ferns, respectively. The one animal in group III was a natural case of enzootic bovine haematuria (EBH) and the two animals in group IV were natural cases of microscopic EBH fed with Polystichum squarrosum fern. In group I animals, the average bladder wall thickness was 1.45 mm. The delineation of the bladder wall was uniformly smooth and the echo pattern of the bladder was homogeneously black, which was suggestive of clear urine content. In group II (P, D and B) the average bladder wall thickness of the six animals was 1.87 mm and the sonographic features were within normal limit when compared with controls. In two of the animals of group II-B, the bladder wall was apparently thick (4.36 mm) and there was no intraluminal mass except at one or two focal elevated points. Animals of groups III and IV showed the average bladder wall thickness of 4.86 mm and were characterized by the presence of irregular sessile masses extending into the bladder lumen. The homogeneous anechoic area was reduced centrally due to the presence of a hypoechoic soft tissue mass all around the bladder wall. Post-sonographic urinalysis, biopsy and necropsy of selected cases further confirmed the sonographic findings.     

Delayed acute capture myopathy in three roe deer

Delayed acute capture myopathy is the term used to describe the clinical syndrome observed in three roe deer captured by drive-nets and transported to an enclosure for scientific purposes. The animals died 48 h, 60 h and 8 days after being captured. The simultaneous deaths coincided with a previous episode of deliberate human disturbance. The histopathological findings were indicative of acute myopathy and myoglobinaemic nephrosis. These could be related to an ataxic myoglobinuric syndrome brought on by capture and transport operations. The lack of clinical signs and negative prognosis indicators in the period between capture and just before death. the absence of gross muscular lesions in the animal that died after 8 days post-capture, the simultaneous deaths of animals captured at different times and the evidence of deliberate human disturbance in the enclosure are suggestive of death triggered by a second stress episode.     

Meal size and starch content affect gastric emptying in horses

REASONS FOR PERFORMING STUDY: Feeding practices have been associated with colic in horses. If meal size and composition have an effect on gastric emptying, this could be one of the mechanisms by which feeding practices are related to the occurrence of colic. OBJECTIVES: To evaluate the effect of meal size and starch content on solid phase gastric emptying. METHODS: Solid phase gastric emptying of 3 different radiolabelled meals, small low-starch (SmLS), small high-starch (SmHS) and large high-starch (LgHS) meals, was measured in 5 horses by scintigraphy using 99mTc-disofenin. Data were compared among meals using nonlinear mixed-effects models and paired t tests. RESULTS: On a percentage basis, SmHS emptied significantly faster than LgHS and SmLS emptied significantly faster than SmHS meals. However, when meals of unequal size were compared by emptying rate in g/min and Kcal/min, LgHS emptied significantly faster than SmHS. CONCLUSIONS: Meal size and composition affect gastric emptying. POTENTIAL RELEVANCE: Further work needs to be performed in order to substantiate the possibility of a relationship between digestive functions and occurrence of colic and gastric ulcers.     

Serotyping and virulence genes detection in Escherichia coli isolated from fertile and infertile eggs, dead-in-shell embryos, and chickens with yolk sac infection

Escherichia coli is a common avian pathogen mainly associated with extraintestinal infections such as yolk sac infection (YSI). The aim of this study was to determine the serotypes and the presence of some virulence genes of E. coli strains isolated from different samples in a vertically integrated poultry operation in Mexico. Two hundred sixty-seven E. coli isolates from different samples were serotyped using rabbit serum against the 175 somatic (O) and 56 flagellar (H) antigens of the typing schema. Virulence genes were determined by colony blot hybridization, using DNA probes for st, eae, agg1, agg2, bfp, lt, cdt, slt, and ipaH diarrhea-associated virulence factors. The serogroup of 85% of the strains was determined; O19 (12%), 084 (9%), 08 (6%), and 078 (5%) were the most common. Using the complete antigenic formula (O and H), O19:NM (n = 31) was the serotype most frequently isolated from dead-in-shell embryos and in broilers that had died on the fourth, fifth, sixth, and seventh days after hatch. One hundred ten strains (41.2%) hybridized with one or more of the used probes. Of these, ipaH (72%), eae (30%), and cdt (27%) were the most common. Considering the origin of the respective isolates, 40% of the broiler farm strains were positive for at least one probe. Results show that some avian E. coli strains isolated in Mexico are included in avian pathogenic E. coli serotypes not previously reported, suggesting that they could be specific for this geographic area. The wide distribution of the ipaH gene among nonmotile strains suggests that this invasiveness trait could be important in YSI pathogenesis. On the other hand, some other genes could contribute to E. coli virulence during YSI.     

Incidence of post-anaesthetic arrhythmias in dogs

OBJECTIVES: To assess the use of Holter monitoring for evaluating the incidence of post-anaesthetic cardiac arrhythmias and associated anaesthetic risk for two different anaesthetic protocols. METHODS: Patients undergoing orthopaedic surgery were randomly divided into two groups with different anaesthetic regimens (group A, isoflurane n = 30; group B, propofol n = 30). Two 24-hour Holter recordings were performed for each patient: the first directly following anaesthesia and the second, as a comparison, on the fifth postoperative day. RESULTS: Although all dogs were healthy on pre-anaesthetic cardiac evaluation, 56 dogs showed arrhythmias in the two 24-hour (Holter) electrocardiograms performed. However, the number of arrhythmias recorded was low in most cases (less than 10 supraventricular extrasystoles and less than 100 ventricular extrasystoles). One patient in group A showed 94 supraventricular extrasystoles during the second monitoring period. Three patients in each group developed more than 100 ventricular extrasystoles during both Holter recordings. There were no statistically significant differences between the two anaesthetic regimens or between the two recordings in both groups. CLINICAL SIGNIFICANCE: The two anaesthetic protocols investigated in this study did not induce an increased incidence of severe arrhythmias in healthy dogs in the post-anaesthetic phase.     

The pharmacokinetics of vedaprofen and its enantiomers in dogs after single and multiple dosing

Vedaprofen is a chiral nonsteroidal anti-inflammatory drug that has been developed as a gel formulation for oral administration to dogs and horses. The pharmacokinetics of vedaprofen and its enantiomers were studied in beagle dogs after single (intravenous solution and oral gel) and multiple (oral gel) dosing at a dosage of 0.5 mg/kg body weight. Plasma concentrations of vedaprofen and its enantiomers were analysed by HPLC. The plasma protein binding of vedaprofen was studied by ultrafiltration. The absorption of vedaprofen was rapid (tmax 0.63 +/- 0.14 h) and almost complete after oral administration (bioavailability 86 +/- 7%). The terminal half-lives after intravenous and oral administration, 16.8 +/- 2.2 and 12.7 +/- 1.7 h respectively, were of the same order of magnitude. Enantioselective analysis showed that the R(-) enantiomer predominated in plasma. The change in the plasma time course of the plasma R(-)/S(+) enantiomer concentration ratio over time was similar after single intravenous and oral dosing, with R(-)/S(+) ratios in the AUC of 1.7 +/- 0.5 and 1.9 +/- 0.2 respectively. Plasma protein binding of vedaprofen and its enantiomers was high (> 99.5%). Vedaprofen is absorbed rapidly from the gastrointestinal tract, has a high bioavailability and does not accumulate in plasma in dogs following repeated oral administration.