The pig industry faces many animal welfare issues. Among these, biting behaviour has a high incidence. It is indicative of an existing problem in biters and is a source of physical damage and psychological stress for the victims. We categorize this behaviour into aggressive and non-aggressive biting, the latter often being directed towards the tail. This review focusses specifically on predisposing factors in early life, comprising the prenatal and postnatal periods up to weaning, for the expression of aggressive and non-aggressive biting later in life. The influence of personality and coping style has been examined in a few studies. It varies according to these studies and, thus, further evaluation is needed. Regarding the effect of environmental factors, the number of scientific papers is low (less than five papers for most factors). No clear influence of prenatal factors has been identified to date. Aggressive biting is reduced by undernutrition, cross-fostering and socialization before weaning. Non-aggressive biting is increased by undernutrition, social stress due to competition and cross-fostering. These latter three factors are highly dependent on litter size at birth. The use of familiar odours may contribute to reducing biting when pigs are moved from one environment to another by alleviating the level of stress associated with novelty. Even though the current environment in which pigs are expressing biting behaviours is of major importance, the pre-weaning environment should be optimized to reduce the likelihood of this problem.

For a long time, scientists assumed that newborns have a severely limited sense of pain (if any). However, this assumption is wrong and led to a “start of the exit” from piglet surgical castration. Some of the currently discussed or already implemented alternatives such as general or local anaesthesia during surgical castration raise additional welfare concerns as well as legal problems and/or are hardly applicable. The favoured long-term, welfare-friendly “gold standard” is to raise entire male pigs (EM). However, this may also impose certain welfare problems under the current conventional housing and management conditions. The specific types of behaviour displayed by EM such as mounting and aggressive behaviours but also increased exploration, which are partially linked to sexual maturation, increase the risk for injuries. The current status of knowledge (scientific literature and farmer experiences) on housing of EM suggests that environmental enrichment, space, group-stability, social constellation, feeding (diet and feeder space), health and climate control are critical factors to be considered for future housing systems. From an animal welfare point of view, an intermediate variant to be favoured to reduce problematic behaviour could be to slaughter EM before reaching puberty or to immunize boars early on to suppress testicular function. Immunization against endogenous GnRH can reduce EM-specific problems after the 2nd vaccination.

This study examined the environmental impact of the three common organic pig husbandry systems, indoor (n = 24), partly outdoor (n = 30), and outdoor (n = 10), in eight European countries. Global warming (GWP), acidification (AP), and eutrophication potential (EP) was assessed per 1000 kg pig live weight on 64 farrow-to-finish pig production chains (cradle to farm gate). GWP, AP, and EP varied greatly, and the most important source was feed production, followed by housing. GWP did not differ between systems (p = 0.934), but AP in indoor systems and EP in outdoor systems were higher than in partly outdoor systems (p = 0.006 and p = 0.010, respectively). The higher AP in indoor systems can mainly be explained by NH₃ arising from manure spreading, while PO₄-eq arising from feed consumption and emissions on pasture accounted for the higher EP in outdoor systems. Associations of farm characteristics with (reduced) environmental impacts were mainly found for AP and EP, and included: (Increasing) farm size, numbers of piglets born and weaned per litter, (bought-in) mineral feed, and high-protein by-products, the latter probably connected to beneficial effects of appropriate dietary digestible lysine levels and feed conversion ratio. Increasing carcass weights and dietary cereal proportions were associated with higher environmental impacts. Overall, variation was mostly higher within than between systems, and measures to mitigate environmental impact were identified.

Dans la plupart des pays, les porcelets mâles sont castrés par voie chirurgicale pour éviter les odeurs sexuelles, lors de la cuisson des viandes, qui sont dues essentiellement à l’androsténone et au scatol. Cette intervention peut légalement être réalisée par l’éleveur sur les porcelets jusqu’à 7 jours d’âge mais pourrait être interdite dans un avenir proche pour des raisons éthiques car elle est très douloureuse. Une alternative consisterait à réduire fortement la douleur liée à la castration. Compte tenu des nombreuses contraintes auxquelles sont soumis les élevages de porcs, très peu de solutions existent. L’une d’elles serait d’associer une anesthésie locale à la lidocaïne avec un traitement antalgique par un anti-inflammatoire. Alternativement, la castration chirurgicale pourrait être remplacée par l’immunocastration ou par la destruction du tissu testiculaire avec des sels minéraux. L’alternative la plus documentée consisterait à immuniser les porcs mâles contre le GnRH mais il n’existe actuellement aucun vaccin ayant un agrément dans l’UE. Par ailleurs, l’acceptabilité par les consommateurs et les conséquences de cette technique sur le bien-être des animaux sont mal connus. L’élevage de porcs mâles entiers pourrait être envisagé mais suppose de réduire le risque d’odeur sexuelle dans la viande et de pouvoir trier les carcasses défectueuses. Les teneurs en scatol et surtout en androsténone pourraient être diminuées par la sélection génétique. La mise en place de conduites d’élevage et de régimes alimentaires appropriés pourrait contribuer à réduire davantage les teneurs en scatol. En conclusion, l’interdiction de la castration chirurgicale poserait de graves problèmes à la filière porcine du fait de l’absence de solution alternative opérationnelle.

La présence d’odeurs indésirables dans la viande de porcs mâles entiers est principalement liée à l’accumulation d’androsténone et de scatol. L’androsténone est synthétisée par les testicules et le scatol par les bactéries du colon à partir du tryptophane. Leur teneur dans le tissu adipeux résulte du bilan entre leur synthèse, leur élimination et leur réabsorption. Le principal levier d’action pour réduire la teneur en androsténone est la sélection génétique. Pour le scatol, les principaux leviers d’action concernent la conduite d’élevage : propreté des cases, gestion de l’environnement microclimatique et conduite alimentaire, notamment. La mixité des groupes et l’instabilité sociale ont peu d’impact sur les teneurs en composés odorants, mais sont importantes à contrôler pour réduire les risques de bagarres et de lésion. Même en réduisant fortement la teneur en composés odorants, il ne sera pas possible d’obtenir des niveaux indétectables sur toutes les carcasses. Une stratégie d’utilisation des carcasses odorantes de porcs mâles entiers doit être définie. Elle implique de comprendre les facteurs de rejet des viandes odorantes par les consommateurs. La perception d’odeurs sexuelles dépend de facteurs liés à l’animal, au type de produit, au mode de préparation/consommation et au consommateur lui-même. De plus, les deux molécules odorantes semblent interagir. La prise en compte des différents cas de figure peut être envisagée par une approche de modélisation, avec en préalable la mise en œuvre d'une détection des odeurs sur la chaine d’abattage. Or actuellement, seule la détection par le nez humain est opérationnelle au niveau des chaines d’abattage et des méthodes instrumentales restent à développer.

Background: Iron from the sow acquired during foetal life and the ingestion of milk is not sufficient to cover the needs of the piglets during their first weeks of life. In organic farming, systematic supplementation with iron is problematic due to a strong limitation in pharmaceutic treatments. Methods: Erythroid parameters around weaning were measured in piglets from organic outdoor and indoor farms, and related to indicators of the inflammatory status. Blood samples were collected from 28.9±2.6 piglets/herd at 42.0±3.2 days of age and 11.9±3.0 kg live weight (mean ± SD) in 21 farms from the west part of France. Among the 11 outdoor farms, only one had supplemented piglets with 200 mg iron while among the 10 indoor farms, only one had not supplemented piglets, one had supplemented them with 100 mg, 8 with 200 mg and one with 400 mg. Results: Compared to outdoor piglets without supplementation, piglets kept indoors and receiving 200 mg iron had lower haemoglobin concentration (105 vs 118±2 g/l, mean ± SE) and red blood cell volume (56 vs 60±1 fl) (P<0.005). The reduction in haemoglobin concentration and red blood cell volume was more pronounced in indoor piglets supplemented with 100 mg of iron and even more when they had not received iron. The plasma concentration of haptoglobin was lower in outdoor than in indoor piglets (0.51±0.06 vs 0.78±0.09 g/l) whereas no effect of housing was observed for markers of oxidative stress (dROM, BAP). In the 14 farms where sow parity was known, the haemoglobin concentration was lower in piglets from primiparous than from multiparous sows (109 versus 114±2 g/l, P <0.001). Conclusion: With the exception of soils where the content of bioavailable iron is very low, piglets from outdoor farms do not require iron supplementation, unlike those raised indoors.