Tree-Based Methods as an Alternative to Logistic Regression in Revealing Risk Factors of Crib-Biting in Horses

Determining the risk factors might help in designing prevention of crib-biting. Logistic regression is a commonly used statistical method for finding risk factors, but tree-based methods are also getting more popular. An important difference between these two statistical approaches is that logistic regression makes a number of assumptions about the underlying data, whereas tree-based methods do not. Another difference is that logistic regression can be used to derive odds ratios for the significant risk factors, whereas tree-based methods create a tree where the ramifications represent the risk factors. The probability of occurrence is assigned to each end of branch in the tree. Data of horses used for noncompetition purposes were analyzed with three statistical approaches: logistic regression, classification tree, and conditional inference tree methods. By this, we compared the advantages and disadvantages of these statistical methods. No difference was found between the two tree-based methods regarding the structure and prediction accuracy of the trees. Compared to them, logistic regression revealed fewer risk factors, and also the number of the stereotypic horses classified correctly by the model was less. The representation of the tree-based methods is closer to medical reasoning and also high-order interaction of the risk-factors can easily be visualized. Our results suggest that tree-based methods can be a new alternative in revealing risk factors, even if used alone or together with logistic regression.     

Ligand-induced changes in Oestrogen and thyroid hormone receptor expression in the developing rat cerebellum: A comparative quantitative PCR and Western blot study

Oestrogen (E2) and thyroid hormones (THs) are key regulators of cerebellar development. Recent reports implicate a complex mechanism through which E2 and THs influence the expression levels of each other's receptors (ERs and TRs) to precisely mediate developmental signals and modulate signal strength. We examined the modulating effects of E2 and THs on the expression levels of their receptor mRNAs and proteins in cultured cerebellar cells obtained from 7-day-old rat pups. Cerebellar granule cell cultures were treated with either E2, THs or a combination of these hormones, and resulting receptor expression levels were determined by quantitative PCR and Western blot techniques. The results were compared to non-treated controls and to samples obtained from 14-day-old in situ cerebella. Additionally, we determined the glial effects on the regulation of ER-TR expression levels. The results show that (i) ER and TR expression depends on the combined presence of E2 and THs; (ii) glial cells mediate the hormonal regulation of neuronal ER-TR expression and (iii) loss of tissue integrity results in characteristic changes in ER-TR expression levels. These observations suggest that both E2 and THs, in adequate amounts, are required for the precise orchestration of cerebellar development and that alterations in the ratio of E2/THs may influence signalling mechanisms involved in neurodevelopment. Comparison of data from in vitro and in situ samples revealed a shift in receptor expression levels after loss of tissue integrity, suggesting that such adjusting/regenerative mechanisms may function after cerebellar tissue injury as well.     

First molecular identification of Mycoplasma ovis and 'Candidatus M. haemoovis' from goat, with lack of haemoplasma PCR-positivity in lice

In order to investigate haemotropic Mycoplasma (formerly Eperythrozoon) infection of goats, blood samples and blood-sucking lice (Linognathus stenopsis) were collected in two goat herds. DNA was extracted from 20 blood samples and from 49 lice allocated to six pools according to host individuals. Haemoplasma infection was detected in four goats by real-time PCR. From the sample with the highest bacterial load the simultaneous presence of M. ovis and 'Candidatus M. haemoovis' was demonstrated by cloning and sequencing. Louse pools were haemoplasma negative, including those from bacteraemic animals. However, not only were Anaplasma inclusion bodies seen in blood smears from goats, but relevant PCR-positivity was also detected among lice. This is the first report of a molecular investigation on caprine haemoplasmas, including analysis of their bloodsucking lice. In summary, goats are susceptible to both molecularly characterised ovine haemoplasmas. On the other hand, goat sucking lice (L. stenopsis) do not appear to be potential vectors of these agents.     

A rabbit model for studying degeneration and regeneration properties of young striated muscle at different distraction rates

The present study evaluated the histological changes in the muscle tissue after limb lengthening in skeletally immature rabbits and assessed the effect of different lengthening rates on the regeneration and degeneration properties of striated muscle. Thirteen different lengthening protocols were applied on a total of 16 male domestic white rabbits divided into four groups. The histopathological changes were analysed by a semiquantitative method according to the scoring system of Lee et al. (1993). After evaluation of the five main degenerative parameters (muscle atrophy, internalisation of muscle nuclei, degeneration of the muscle fibre, perimysial and endomysial fibrosis, haematomas), it is evident that rabbits subjected to limb lengthening at a rate of 3.2 mm/day showed more degenerative changes than those limb-lengthened at 0.8 or 1.6 mm/day. Our study showed that the regenerative mechanisms were not endless. If the daily lengthening rate reached the 3.2 mm/day limit, the regenerating ability of the muscle decreased, and signs of degeneration increased significantly.     

Seasonal fertility differences in synchronised dairy cows: ultrasonic, metabolic and endocrine findings

The aim of this study was to identify relationships among seasonal differences of fertility, metabolic parameters and appearance of irregular luteal forms in high-yielding dairy cows. Holstein-Friesian cows were put on the Provsynch regimen in winter (n = 10) and in summer (n = 10). Blood sampling (starting 35 days post partum) and rectal ultrasound examinations (starting post insemination) were carried out once a week in each examination period. Metabolic [plasma nonesterified fatty acid (NEFA) and beta-hydroxybutyrate (BHB) levels, ferric reducing ability of plasma (FRAP) and serum beta-carotene] and endocrine parameters [plasma thyroxine (T4), triiodothyronine (T3), insulin-like growth factor (IGF-I) and insulin levels] were measured. In summer, two cows were excluded from the study because of metritis and none of the remaining animals became pregnant, but 6 of the 8 cows had irregular luteal forms (ILF) on their ovaries. In winter, one cow was excluded because of metritis and 6 of the 9 cows became pregnant, while 2 of the 3 open cows had irregular luteal forms. In summer the mean plasma NEFA and BHB concentrations were significantly higher, while serum carotene and plasma IGF-I concentrations were significantly lower than in winter. The high plasma NEFA concentration found in summer seemed to be in association with the lower body condition score (BCS) caused by depressed appetite. In conclusion, statistical analysis supports the hypothesis that increased plasma NEFA and BHB and decreased plasma IGF-I concentrations may result in reduced fertility in summer. These changes may be associated with the more frequent appearance of ILFs and probably have a negative effect on ovarian function and/or oocyte quality.     

Grfahrungen aus dem Gebiete der niedern Jagd von C. G. Diezel. 2 Abtheilungen. 2. Auflage. Cotha,Scheube. 1856

Ohne Zusammenfassung     

Effect of a dietary supplementation with linseed oil and selenium to growing rabbits on their productive performances,carcass traits and fresh and cooked meat quality

The present experiment tested a dietary supplementation with linseed oil and selenium to growing rabbits. The basal diet (B) contained 3% sunflower oil, while it was substituted with 3% linseed oil in the experimental feed (S). The selenium (Se) content of the two diets was 0.10 vs. 0.46 mg/kg. Rabbits were fed with B diet from the age of 18 days. One group was fed with the B diet until 11 weeks of age (group B), whereas the experimental groups were fed with S diet for 1, 2, 3 or 4 weeks (groups S1, S2, S3 and S4, respectively), before slaughtering (11 weeks of age). Live performance and carcass traits of rabbits, fatty acid (FA) profile and selenium content of their hind leg (HL) and Longissimus thoracis et lumborum (LTL) meat were considered in this study. In addition, the effect of two different cooking methods on the nutritional value of the enriched HL meat was also assessed. The tested dietary supplementation only minimally affected the live performance and carcass traits of rabbits. The S supplementation significantly reduced the Σ n‐6 FA and increased the Σ n‐3 FA of the HL meat and LTL meat, compared to the B diet (p < 0.001); thus, n‐6/n‐3 ratio was improved (p < 0.001). In addition, HL meat and LTL meat of S fed rabbits were significantly enriched in Se reaching a twofold increase in both meat cuts (p < 0.01). Therefore, the S supplementation improved the functional value of the rabbit meat. The heat treatment affected cooking loss, Se and vitamin E contents as well as the oxidative status of the HL meat (p < 0.001), with the different cooking methods providing different results. In addition, even if the beneficial C20:5 n‐3 and C22:6 n‐3 decreased with cooking, the n‐6/n‐3 ratio remained unaffected.     

Phenology,behavior and infestation levels of the invasive small cypress bark beetle, <Emphasis Type="Italic">Phloeosinus aubei</Emphasis>, on some cultivars of <Emphasis Type="Italic">Thuja</Emphasis> and <Emphasis Type="Italic">Juniper</Emphasis> spp., in Hungary

The invasive small cypress bark beetle, Phloeosinus aubei (Coleoptera, Curculionidae, Scolytinae) has two flights in Central-Europe, however, it was unclear, whether this corresponds to two reproductive periods, when nuptial chambers are formed and galleries initiated. The aim of this study was to clarify the life-cycle of P. aubei in Hungary, representing populations in the range of invasion, and to compare preferences towards some popular cultivars of Thuja and Juniper ornamental trees. In order to reveal which is the pioneering gender, and to confirm females’ preferences between healthy and broken trunks behavioral tests were conducted. Results showed that adults prepare hibernation tunnels from August until October. Sex ratio of overwintering adults was nearly equal. The significantly highest number of hibernation tunnels was found on Thuja plicata Atrovirens (mean±S.E.: 6.0±0.7/tree), followed by T. occidentalis Smaragd (2.2±0.8), Juniperus chinensis Spartan (1.6±0.6), and J. scopulorum Blue Arrow (0.2±0.2). Nuptial chambers were made from April until June, by singly females, never by males. Females chose broken, drying trunks over healthy ones. Adults of the next generation emerged from the galleries from August until October. By October adults emerged from 94% of the galleries, and larvae were found only in 6% of the galleries. These results showed that the autumn flight of P. aubei is linked to making hibernation tunnels, while the spring flight to producing nuptial chambers. The latter corresponds to a single reproductive period per year. Control measures against adults should be timed to these two specific periods of the season.