Identification of markers of the robustness of piglets at weaning

La notion de robustesse peut se définir par le maintien des performances et de la santé quelles que soient les conditions d’environnement. Le sevrage constitue la phase où la plus grande quantité d’antibiotiques est utilisée car il est source de perturbations multiples pour le porcelet. L’identification de porcs robustes permettrait d’envisager des soins spécifiques et/ou une sélection génétique sur ce caractère. Les objectifs de cette thèse étaient d’identifier certains marqueurs physiologiques associés à la robustesse du porcelet au sevrage et de prédire cette robustesse par des variables physiologiques décrivant ces réponses mesurées avant et après sevrage. Pour répondre à cet objectif, des variables physiologiques ont d’abord été mesurées dans des environnements très divers puis celles associées à la robustesse ont été identifiées. Une première étude a été conduite en installation expérimentale visant à étudier les effets de l’âge, des conditions de sevrage et de la santé sur l’évoPar ailleurs, dans une deuxième étude, des variables physiologiques ont été mesurées dans 16 élevages commerciaux autour du sevrage. Les performances de croissance et le statut sanitaire étaient les 2 facteurs de variations d’élevages contrôlés. L’analyse des données a permis de mettre en évidence une forte influence du statut sanitaire sur les variables physiologiques mesurées autour du sevrage. Des variables descriptives du statut oxydant, du statut métabolique et de l’activation du système immunitaire ont été associées à la robustesse du porcelet au sevrage. Ainsi, les porcelets les plusThe concept of robustness can be defined as the ability to maintain performances and health whatever environmental conditions. Weaning is the step where the biggest part of antibiotics is used because it is the source of multiple perturbations for the piglet. The identification of robust pigs could allow settling specific care and/or genetic selection on this criteria. The objectives of this thesis were to identify physiological parameters associated with the robustness of piglet at weaning and to predict this robustness by biological variables describing those measured responses before and after weaning. To answer to this objective, physiological variables were first measured in very different environments and, then, those ones associated with the robustness were identified. A first experiment was realized in experimental unit, aiming to study the effects of age, weaning conditions and health on the evolution of blood variables describing immune and metabolic status, stress and oxidatGrowth performances and health status were the two controlled factors of variations of farms. The analysis of data allowed us to show a high influence of health status on physiological variables around weaning. Some variables describing oxidative status, metabolic status and the activation of immune system were associated with the robustness of piglet at weaning. Thus, the most robust piglets are those ones who, in favorable or unfavorable environments, have a capacity to limit their oxidative stress, to mobilize less body reserves and to activate quickly their immune system. Those variable

Identification de marqueurs de la robustesse du porcelet au sevrage

The concept of robustness can be defined as the ability to maintain performances and health whatever environmental conditions. Weaning is the step where the biggest part of antibiotics is used because it is the source of multiple perturbations for the piglet. The identification of robust pigs could allow settling specific care and/or genetic selection on this criteria. The objectives of this thesis were to identify physiological parameters associated with the robustness of piglet at weaning and to predict this robustness by biological variables describing those measured responses before and after weaning. To answer to this objective, physiological variables were first measured in very different environments and, then, those ones associated with the robustness were identified. A first experiment was realized in experimental unit, aiming to study the effects of age, weaning conditions and health on the evolution of blood variables describing immune and metabolic status, stress and oxidatGrowth performances and health status were the two controlled factors of variations of farms. The analysis of data allowed us to show a high influence of health status on physiological variables around weaning. Some variables describing oxidative status, metabolic status and the activation of immune system were associated with the robustness of piglet at weaning. Thus, the most robust piglets are those ones who, in favorable or unfavorable environments, have a capacity to limit their oxidative stress, to mobilize less body reserves and to activate quickly their immune system. Those variablesLa notion de robustesse peut se définir par le maintien des performances et de la santé quelles que soient les conditions d’environnement. Le sevrage constitue la phase où la plus grande quantité d’antibiotiques est utilisée car il est source de perturbations multiples pour le porcelet. L’identification de porcs robustes permettrait d’envisager des soins spécifiques et/ou une sélection génétique sur ce caractère. Les objectifs de cette thèse étaient d’identifier certains marqueurs physiologiques associés à la robustesse du porcelet au sevrage et de prédire cette robustesse par des variables physiologiques décrivant ces réponses mesurées avant et après sevrage. Pour répondre à cet objectif, des variables physiologiques ont d’abord été mesurées dans des environnements très divers puis celles associées à la robustesse ont été identifiées. Une première étude a été conduite en installation expérimentale visant à étudier les effets de l’âge, des conditions de sevrage et de la santé sur l’évoPar ailleurs, dans une deuxième étude, des variables physiologiques ont été mesurées dans 16 élevages commerciaux autour du sevrage. Les performances de croissance et le statut sanitaire étaient les 2 facteurs de variations d’élevages contrôlés. L’analyse des données a permis de mettre en évidence une forte influence du statut sanitaire sur les variables physiologiques mesurées autour du sevrage. Des variables descriptives du statut oxydant, du statut métabolique et de l’activation du système immunitaire ont été associées à la robustesse du porcelet au sevrage. Ainsi, les porcelets les plu

Looking to biological variables predicting growth during the first three weeks after weaning in pig

Pig production needs to conciliate the reduction of the use of antibiotics and animal welfare while maintainingprofitability. The early detection of animals with high risks of diseases could allow the implementation of individual care and/or treatments. This study aims to look for the association of health of piglets after weaning with biological variables measured before or immediately after weaning. Growth was used here as a rough indicator of health. Piglets (n=270) coming from 15 commercial farms, weaned at 28 days of age, were blood sampled at 26 and 33 days of age and weighed at 26, 33, 47 days of age. Biological parameters (n=19) concerning immunity, stress, oxidative stress or nutrients metabolism were measured. Considering the strong correlation between average daily gain (ADG) and live weight, the relative 26/47 ADG, calculated as the ratio of ADG between 26 and 47 days of age and live weight at 26 days of age, was used. A linear model was built for each biological variable, testing its explanatory role on relative 26/47 ADG. Then a Bonferroni correction was implemented and all variables with significance below 0.1 were included together in a final model. This model included farm effect, plasma day 26 hemoglobin and day 33 creatinine, non-esterified fatty acids (NEFA) and vitamin A plasma concentrations. The model explained 43% of the variance of relative 26/47 ADG with 31% accounting for farm effect and 6% for creatinine concentration. Apart from farm effect, piglets having a low relative 26/47 ADG displayed low hemoglobin concentration before weaning, and high protein (high creatinine) and energy (high NEFA) mobilization and low antioxidant concentration of vitamin A in blood after weaning. This study gives promising insights of the early detection of piglets with low relative growth after weaning

Oxidative stress as marker of piglet health at weaning

Weaning is a source of social, nutritional and environmental changes for piglets, that challenge its health. This study aims to assess the opportunity to use plasma hydroperoxide (dROM) concentration and antioxidant capacity (BAP), two indicators of oxidative status, as indicator of piglet health in the context of weaning. In order to dissociate effects of age and management conditions on the evolution of oxidative status around weaning, a study was carried out, where piglets were followed from 12 to 147 days of age, and weaned at 21 or 28 days of age in optimal (OC) or deteriorated (DC) conditions (n=16 per group). Oxidative products (dROM), antioxidant capacity (BAP), vitamin E and A were measured in plasma. DC piglets had lower ADG (P<0.001) and more diarrhea (P<0.01) between 0 and 19 days after weaning compared to OC piglets. Oxidative stress index (OSI, dROM/BAP) increased for DC but not OC piglets after weaning (P<0.01) due to increased dROM (P=0.05) and decreased BAP (P<0.05). Piglets which exhibited diarrhea between 0 and 19 days after weaning had higher OSI (P<0.001) and dROM (P<0.01) 12 days after weaning. The concentrations of vitamin E and A dropped after weaning (P<0.001). Present data indicate that oxidative stress index can be affected by sub-optimal weaning conditions such as deteriorated management conditions and exhibition of diarrhea. Therefore, oxidative stress index seems to be a relevant candidate as an indicator of piglet health in the context of weaning

Oxidative stress as marker of piglet health at weaning

Weaning is a source of social, nutritional and environmental changes for piglets, that challenge its health. This study aims to assess the opportunity to use plasma hydroperoxide (dROM) concentration and antioxidant capacity (BAP), two indicators of oxidative status, as indicator of piglet health in the context of weaning. In order to dissociate effects of age and management conditions on the evolution of oxidative status around weaning, a study was carried out, where piglets were followed from 12 to 147 days of age, and weaned at 21 or 28 days of age in optimal (OC) or deteriorated (DC) conditions (n=16 per group). Oxidative products (dROM), antioxidant capacity (BAP), vitamin E and A were measured in plasma. DC piglets had lower ADG (P<0.001) and more diarrhea (P<0.01) between 0 and 19 days after weaning compared to OC piglets. Oxidative stress index (OSI, dROM/BAP) increased for DC but not OC piglets after weaning (P<0.01) due to increased dROM (P=0.05) and decreased BAP (P<0.05). Piglets which exhibited diarrhea between 0 and 19 days after weaning had higher OSI (P<0.001) and dROM (P<0.01) 12 days after weaning. The concentrations of vitamin E and A dropped after weaning (P<0.001). Present data indicate that oxidative stress index can be affected by sub-optimal weaning conditions such as deteriorated management conditions and exhibition of diarrhea. Therefore, oxidative stress index seems to be a relevant candidate as an indicator of piglet health in the context of weaning

Effects of age and weaning conditions on blood indicators of oxidative status in pigs.

Weaning is a source of social, nutritional and environmental disorders that challenge piglet health. This study assesses the relevance of using plasma indicators of oxidative status as biomarkers of health around weaning in pigs. Blood antioxidant potential (BAP), hydroperoxides (HPO), oxidative stress index (OSI, e.g. HPO/BAP), vitamin A and E concentrations were investigated in two different trials. Trial A was carried out in an experimental unit to investigate the effects of age (from 12 to 147 days of age), weaning (at 21 or 28 days of age) and management at weaning (in optimal (OC) or deteriorated (DC) conditions) on those parameters. Trial B was performed in 16 commercial pig farms to describe the variability of these indicators on field between 26 and 75 days of age. In trial A, between 12 and 147 days of age, HPO globally increased (P 0.1). Vitamins E and A concentrations dropped 5 days after weaning independently of weaning age, weaning conditions and expression of diarrhea (P < 0.001). Twelve days after weaning, whatever the weaning age, HPO and OSI increased in DC compared to OC piglets (P = 0.05 and P < 0.01) and in piglets exhibiting diarrhea compared to those without diarrhea (P < 0.01 and P < 0.001). In DC pigs, BAP was also decreased (P < 0.05) 12 days after weaning. On trial B, plasma concentrations of vitamins A and E decreased and HPO increased 5 and 19 days respectively after weaning (P < 0,001). Contrarily to trial A, BAP values did not drop after weaning. Piglets which had the lowest ADG (Average Daily Gain) after weaning had greater HPO and OSI and lower vitamin A and E concentrations after weaning but also lower vitamin E concentration before weaning (P < 0.05). In conclusion, HPO or OSI seem to be good indicators of health disorders around weaning and plasma concentration of vitamin E before weaning is associated to growth after weaning

Effects of weaning conditions on the evolution of piglet plasma concentration of vitamin E

Weaning causes oxidative stress in piglets. Endogenous and exogenous vitamin E (vit E) participates to theneutralization of pro-oxidant molecules in the organism. This study aimed to analyze the effect of weaning conditions on the evolution of plasma vitamin E concentration on piglets. In trial A, piglets born from 12 litters were weaned at either 21 (W21) or 28 (W28) days of age in optimal (OC) or deteriorated (DC) conditions (n=16 per group). Piglets from OC group originating from 2 litters were housed by 4 (0.39 m2/pig) in cleaned and disinfected pens. Those from DC group originating from 4 litters were housed by 8 (0.20 m2/pig) in dirty pens after a waiting time of 4 h at 20 °C. From 12 to 61 days of age, blood was collected and pigs were weighed weekly and then at 88, 119 and 147 days of age. In trial B, piglets (n=288 from 144 sows) from 16 commercial farms were weaned at 28 days of age. Blood samples were collected when piglets were 26- (on sows and piglets) and 33-days old (on piglets only). In both trials, weaning led to a dramatic drop of the plasma concentration of vit E (P0.05). After weaning, vit E concentration remained stable until 147 days of age. In trial B, piglet plasma concentration of vit E at 26 days of age was not associated with lactating sow vit E concentrations (P>0.05) and was different between farms (P<0.001). The higher plasma concentration of vit E before weaning could be explained by the high vit E content in colostrum and milk leading to the saturation of body fat reserves of the piglet. At weaning, the high requirements of vit E for antioxidant purposes as well as low feed intake, lower fat content of the feed compared to milk and lower activity of enzymes involved in vit E absorption could explain the dramatic drop of plasma vit E. The relatively low concentrations of vit E until slaughter age could reflect an incomplete reconstitution of body reserves. To conclude, weaning led to a drop of plasma concentration of vit E whatever the weaning conditions indicating dramatic changes in vit E statusand metabolism at weaning

Antibiotic Use in Relation with Psychological Profiles of Farmers of a French Pig Cooperative

International audience(1) Background: We focus on the psychological factors that influence pig farmers’ antibiotic use, which is not exclusively determined by the technical, health and structural factors of livestock farming. (2) Methods: We visited farming sites and asked 91 pig farmers about various psychosocial dimensions that could be considered relevant in explaining antibiotic use. (3) Results: The results indicate the existence of three livestock-farmer sub-profiles, each of which is associated with distinct psychological characteristics and antibiotic use levels. (4) Conclusions: We discuss the implications of antibiotic use for livestock in terms of communication and support