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In pig production, efficiency is benefiting from uniform growth in pens resulting in single deliveries from a pen of possibly all animals in the targeted weight range. Abnormalities, like pneumonia or aberrant growth, reduce production efficiency as it reduces the uniformity and might cause multiple deliveries per batch and pigs delivered with a low meat yield or outside the targeted weight range. Early identification of pigs prone to develop these abnormalities, for example, at the onset of the growing-finishing phase, would help to prevent heterogeneous pens through management interventions. Data about previous production cycles at the farm combined with data from the piglet’s own history may help in identifying these abnormalities. The aim of this study, therefore, was to predict at the onset of the growing-finishing phase, that is, at 3 mo in advance, deviant pigs at slaughter with a machine-learning technique called boosted trees. The dataset used was extracted from the farm management system of a research center. It contained over 70,000 records of individual pigs born between 2004 and 2016, including information on, for example, offspring, litter size, transfer dates between production stages, their respective locations within the barns, and individual live-weights at several production stages. Results obtained on an independent test set showed that at a 90% specificity rate, the sensitivity was 16% for low meat percentage, 20% for pneumonia and 36% for low lifetime growth rate. For low lifetime growth rate, this meant an almost three times increase in positive predictive value compared to the current situation. From these results, it was concluded that routine performance information available at the onset of the growing-finishing phase combined with data about previous production cycles formed a moderate base to identify pigs prone to develop pneumonia (AUC > 0.60) and a good base to identify pigs prone to develop growth aberrations (AUC > 0.70) during the growing-finishing phase. The mentioned information, however, was not a sufficient base to identify pigs prone to develop low meat percentage (AUC < 0.60). The shown ability to identify growth aberrations and pneumonia can be considered a good first step towards the development of an early warning system for pigs in the growing-finishing phase.

In five successive pilot experiment different park layouts were tested with the objective to minimize skin injuries in group-housed rabbit does. Does were single housed in so called combi-parks. At 21 or 23 days of lactation the separations between six single parks were removed to create a group-park (combi-park system). The park layout was altered by changing the place of wooden panels underneath and up the platform. In this way different hide and escape routes were created. The panels between the nest boxes remained. In the fifth pilot also the panels between the nest boxes were removed creating a so called park that is also used in meat rabbits. In the parcs were the nest box panels were also removed no severe skin injuries were observed. Therefore, park layout seems to influence skin injuries. Results have to be treated with care, as the pilots were performed with small numbers and not repeated. Dit rapport doet verslag van een serie van vijf opeenvolgende pilotproeven met beperkt aantal herhalingen die zijn uitgevoerd met betrekking tot parttime groepshuisvesting van voedsters in de commerciële konijnenhouderij. Hokindeling en daarmee de mogelijkheid voor voedsters om van elkaar weg/uit zicht te kunnen komen (vluchten) lijkt een belangrijke bijdrage te kunnen leveren in het verminderen en tijdig beëindigen van rangordestrijd tussen voedsters. Daarom zijn in de pilots verschillende hokindelingen onderzocht. Er is geëxperimenteerd met verschillende hokindelingen in zogenaamde combi-parken door het plaatsen van schotten onder en op het platform. Dit leek geen effect te hebben op het optreden van huidbeschadigingen en daarmee rangorde strijd tussen voedsters. In de hokken waarin naast de tussenwanden ook de nestkastafscheidingen waren verwijderd werden geen ernstig beschadigde voedsters aangetroffen. Hokindeling lijkt daarmee van invloed op het optreden van huidbeschadigingen. De pilots zijn echter met een beperkt aantal herhalingen uitgevoerd. De uitkomsten dienen daarom met enige voorzichtigheid te worden gehanteerd.

[EN] Group housing of lactating rabbit does is desirable from a welfare standpoint, but agonistic behaviour can cause severe skin injuries, which are undesired for animal welfare. Park layout, creating hiding places and escape possibilities, may help redirect attention away from fighting, which could in turn help prevent skin damage. An experiment was performed to test whether more damaging behaviour would occur in a combi park (with nest box panels) after mixing, compared to a regular park for fatteners, as nest box panels would obstruct does when escaping aggressive interactions. In addition, the position of the PVC pipe underneath the platform differed between parks (longitudinal or transversal), resulting in different escape routes. Twenty-two parks were used, in which 5 does per park were grouped at 23 d of lactation until weaning at 36 d of lactation. Skin injuries were scored at 4 d after grouping and on the day before weaning. The presence of nest box panels in a combi park and the position of the PVC pipe underneath the platform did not affect the level of skin damage. Moderate to severe injuries were observed, mostly at the hind quarters, ears and head. Five to 6% of the does were severely injured (wounds). There was a positive relationship between the average skin injury per park at 4 d after grouping and at weaning. On average, average injury score per park increased from grouping to weaning, but there are differences between individual parks. From this experiment it can be concluded that group housing of lactating rabbit does involves animals getting injured. In fact, 5 to 6% of the does were severely injured (wounds). Social dynamics of group housed does are insufficiently understood and might be important to reduce damaging behaviour in group housing., This study was financed by the PPS “Duurzame konijnenhouderij” (TKI-AF-15234) and the Ministry of Economic Affairs. We thank Mr and Mrs Slegh, at whose farm the experiment was conducted. Without their help this experiment would not have been possible.

The GH-IGF-I axis is of major importance for the regulation of body growth and composition, and cellular proliferation and differentiation processes. Selective breeding aiming to improve growth rate and/or body composition is accompanied by changes of the GH-IGF-I axis. Research aiming to elucidate the genetic and physiologic mechanism(s) underlying these changes may best use single-trait selection lines. Two such pig selection lines, one for growth rate and one for high lean content, were used in experiments to investigate the mechanisms of the GH-IGF-I axis change during selection. This contribution reviews the selection-related changes in the GH-IGF-I axis as the consequences of selection for whole body growth rate or body composition and effects on local tissue growth rate. A model explaining the observed effects and consequences for the pressure on the physiology is presented. In short, selection related demand for GH induces GH synthesis until a limit is reached. After that the pulsatile GH plasma profile changes, which may also affect expression profiles of genes regulating body composition. (C) 2004 Elsevier Inc. All rights reserved.