Recording strategies and selection potential of feed intake measured using the X-ray method in rainbow trout

v2006okBEL/BG

Kvaliteta uzorkovanja kod sustavnog praćenja goveđe spongiformne encefalopatije u Belgiji.

The bovine spongiform encephalopathy (BSE) epidemics have led to active surveillance in Europe. Detection methods are focused on the obex, where prions first accumulate in the central nervous system (CNS). Sampling is made with a calibrated syringe (from Bio-Rad or Idexx) that must sample a target area in the obex area. This study checked the precision of the sampling in Belgian routine laboratories in 2010 and 2011 (analysed obex: N = 184 and N = 368). For that purpose, the obex was divided into 130 identical square zones with 50 in the target area. The success of sampling the target area was identical when comparing the years (72.8%). The different laboratories obtained similar results. However, in 2011, one of the four laboratories had a lower number of zones inside the target area than the best laboratory. As a conclusion, obex sampling in Belgium is adequate, provided the technicians are well trained. This is especially true when confronted with atypical BSE, for which the obex is not the primary region of prion accumulation.Epidemije goveđe spongiformne encefalopatije nužno su dovele do donošenja mjera za njezin aktivni nadzor u Europi. Metode dokazivanja usmjerene su na obex u središnjem živčanom sustavu gdje se prioni najprije nakupljaju. Uzorci se uzimaju kalibriranom štrcaljkom (Bio-Rad ili Idexx) na ciljnom mjestu na području obeksa. U ovom istraživanju provjerena je točnost uzimanja uzoraka u rutinskim dijagnostičkim laboratorijima u Belgiji u 2010. i 2011. kada je bilo analizirano 184 odnosno 368 uzoraka tkiva obeksa. U tu je svrhu obex bio podijeljen na 130 identičnih kvadratičnih područja s 50 ciljnih mjesta. Uspješnost uzimanja uzoraka s ciljnog mjesta bila je identična na godišnjoj razini (72,8%). Različiti laboratoriji postigli su slične rezultate. Ipak, u 2011. jedan od četiri laboratorija imao je manji broj zona unutar ciljnog područja u usporedbi s rezultatima najboljeg laboratorija. Zaključuje se da je uzimanje uzoraka tkiva obeksa u Belgiji zadovoljavajuće i da je tehničko osoblje dobro educirano. To je osobito važno kad je riječ u atipičnoj goveđoj spongiformnoj encefalopatiji kod koje obex nije primarno područje nakupljanja priona

Recording strategies and selection potential of feed intake measured using the X-ray method in rainbow trout

This study examines the way long-term feed intake should be recorded accurately for selective breeding purposes, and estimates selection potential in feed intake using the X-ray method to record individual daily feed intake in rainbow trout (Oncorhynchus mykiss). The analysis showed that the point estimates of daily feed intake displayed low repeatabilities (r = 0.09–0.32). This indicates that a minimum of three repeated records were needed to accurately record average feed intake at a fixed age. To effectively breed for feed intake over the whole growing period, it is necessary to determine average feed intake at different ages, since there were only moderate phenotypic and genetic correlations between average daily feed intake recorded at 140 g, 750 g and 2000 g wet mass. Heritability for average daily feed intake was low (average h2 = 0.10), indicating that modest genetic changes can be obtained in response to selection. It was concluded that selection to genetically change long-term feed intake can be successful, yet repeated observations at several life stages are needed to ensure the accuracy of feed intake estimates and the efficiency of selection

No H- and L-type cases in Belgium in cattle diagnosed with bovine spongiform encephalopathy (1999-2008) aging seven years and older

<p>Abstract</p> <p>Background</p> <p>The bovine spongiform encephalopathy (BSE) epidemic presented homogeneity of the phenotype. This classical BSE (called C-type) was probably due to the contamination of the food chain by a single prion strain. However, due to the active surveillance and better techniques, two rare variants of BSE have been recently reported in different continents without a clear correlation to the BSE epidemic. These emerging types behave as different strains of BSE and were named H-type and L-type according to the high and low molecular mass of the unglycosylated fragment of their proteinase K resistant prion protein (PrP^res). In these types, the proportion of the un-, mono- and di-glycosylated fragments of PrP (glycoprofile) is also atypical and represents an effective diagnostic parameter. This study evaluated the presence of such types in bovine of 7 years and older in Belgium.</p> <p>Results</p> <p>The Belgian BSE archive contained 41 bovines of at least 7 years of age. The biochemical features of their PrP^reswere analyzed by Western blot with five antibodies recognising different regions of PrP^res, from N- to C-terminus: 12B2, 9A2, Sha31, SAF84 and 94B4. All antibodies clearly detected PrP^resexcept 12B2 antibody, which is specific for N-terminal region 101-105, a PrP region that is only retained in H-types. The glycoprofiles did correspond to that of C-type (with more than 55% of diglycosylated PrP^resusing antibody 94B4). Therefore, all cases have the features of C-type BSE.</p> <p>Conclusions</p> <p>This study supports that, among the BSE cases of 7 years and older identified in Belgium, none was apparently of the H- or L- type. This is consistent with the very rare occurrence of atypical BSE and the restricted dimension of Belgium. These results shed some light on the worldwide prevalence of atypical BSE.</p

Breeding suppression between two unrelated and initially unfamiliar females occurs with or without social tolerance in common voles (Microtus arvalis)

Female common voles can breed in small groups or in isolation. Given the option, will isolated females opt for communal breeding with unrelated females and a probable low reproductive bias, or will they remain isolated, forgoing the advantages of group living? This laboratory work examined the response of two unrelated females to a foreign male in order to determine their social and breeding strategies. Before encountering a male, 70% of the females lived communally and 30% were solitary with a dominance hierarchy. In the presence of the male, only 33% of the females were still associated and lived with the male in a communal nest. In the other triads, only the oldest female lived with the male and she dominated the younger female. Although all animals were then experimentally separated to avoid late abortion due to social stress or infanticide, in 89% of the dyads only one female littered. This breeding suppression happened in hierarchic dyads but also in tolerant ones. This laboratory study on the social influence on reproduction showed that breeding suppression can occur in unrelated female common voles even when they are not closely grouped. It suggests that cooperative breeding between unrelated females should remain rare. © Japan Ethological Society and Springer 2008.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Etude au laboratoire de l'organisation sociale, des stratégies reproductives et du marquage odorant chez le campagnol des champs, Microtus arvalis (Pall.) 1778

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Etude au laboratoire de l'organisation sociale, des stratégies reproductives et du marquage odorant chez le campagnol des champs, Microtus arvalis (Pall.) 1778

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Scent marking by common voles Microtus arvalis in the presence of a same-sex neighbour

Several vole species use scent marked runways radiating from their burrows for foraging and dispersion. These marks are probably used for social communication. This 4-day laboratory study investigated the environmental and social causations of marking inside pre-existing corridors in male and female common voles Microtus arvalis (Pallas, 1778). Firstly I tested the novelty and the reinforcement hypotheses in isolated voles, predicting respectively a habituation or a continuous increase in mark deposition. I then confronted with each other two same-sex voles for two days to investigate the differences between males and females in the pattern of marks inside three corridors, one of which runs along the common partition with the neighbour. I tested the self-advertisement and territorial-defence hypotheses, respectively predicting in the presence of a neighbour either a similar marking between the three corridors or a greater marking in the corridor close to the neighbour than in the two other corridors. The results showed no habituation in marking, even in a familiar environment, confirming the reinforcement hypothesis. After the addition of a neighbour, only the females left more marks in the corridor that ran alongside the common border than in the two other corridors. The territorial-defence hypothesis was thus confirmed in (territorial) females while the self-advertisement was supported in (non-territorial) males. Finally, I tested the competitive-ability hypothesis in females, stating that the abundance of scent marks of an individual before a social interaction can predict its degree of intolerance in a future social interaction. The results from female pairs physically interacting for four days support the hypothesis.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Movement patterns of male common voles (Microtus arvalis) in a network of Y junctions: Role of distant visual cues and scent marks

Common voles (Microtus arvalis) use networks of runways around their burrows, which are dug in meadows. Their orientation among such networks could be based on rigid "egocentred" routes (possibly through the use of olfactory "trails") or on more general, "allocentred" spatial representations (with distant visual cues). In this 5-day study, male voles should reach food in the centre of a maze of three-way (Y) junctions offering similar local views but surrounded by distant visual cues. I tested whether the animals navigated using olfactory trails, implying one main direct foraging route, or allocentered representations, allowing flexibility among equivalent routes. Males quickly marked their environment, preferentially at the periphery, where they moved the most. However, during most direct trips between the nest and the food, they used one of the central shortest routes, which included the least scent-marked zones. Moreover, the voles preferred different shortest routes to go to the food and return from it, showing a bias in favour of the side where the distant goal (food or nest) was situated. This suggests that male common voles base their choices on the general direction of their goal rather than on trails. Finally, there was no major difference in initial exploration between a clean and a scent-marked maze.SCOPUS: ar.jinfo:eu-repo/semantics/publishe