Salmonella control within the pyramidal structured network of pigs\u27 movements in France

Due to economical and public health consequences, control of Salmonella spread within pig herds is a major concern for the swine industry. A better understanding of the links between herds as well as between herds and slaughterhouses within a production stmcture is then needed to assess the effect of possible control measures at this level. In the French pork production chain, herds have specific links between them: some herds being animals suppliers for others. This organization induces a specific complex network in which the contacts between herds are hierarchized, dynamic and directed. We present here a modelling approach to assess the effect of control measure implementation on the Salmonella spread within the pyramidal structure of French pork production chain, coupled with the within-herd dynamics to represent the spread of Salmonella. Firstly, the susceptibility of the pyramidal organization to an external infection is tested. The number of infected herds at the end of the simulation is highly variable according to the initial infected herd (type of herd, level of the pyramid). Secondly, we assess the effect of a control measure implementation on the seroprevalence in groups of slaughter pigs. This measure, which consists in restricting animals\u27 purchases according to the infectious status of herds combined with a reduction of within herd transmission of Salmonella, leads to decrease the number of highly contaminated herds. This modeling approach allows us to investigate the impact of control measures both at the within and the between-herds level

Modelling the prevalence of Salmonella carrier pigs at slaughtering age: influence of management systems and of the Salmonella status of replacement gilts

To reduce Salmonella contamination of pork food cham at the farm level, control actions can aim at preventmg the introduction of the bactena into herds or/and at preventing the in-herd transmission. Our aim is to estimate the influence of (i) the decontamination efficiency and (ii) the Salmonella status of replacement gilts on the prevalence of carrier pigs at slaughtering age. We developed a stochastic mathematical model to simulate the pig population dynamics and the Salmonella transmiss1on withrn a farrow-to-finish herd. Results show a different prevalence of carnage in groups of delivered pigs according to the scenarios tested

A model of energy allocation to predict adaptive capacities in meat sheep

Publishe

Modelling adaptation strategies to climate change in Mediterranean small ruminant systems

PRIMA AdaptHerd projec

Exploring climate change adaptation strategies form the perspective of Mediterranean sheep farmers

PRIMA project Adapt-Her

Climate change and future scenarios for palisade grass production in the state of São Paulo, Brazil

The objective of this work was to analyze future scenarios for palisade grass yield subjected to climate change for the state of São Paulo, Brazil. An empirical crop model was used to estimate yields, according to growing degree-days adjusted by one drought attenuation factor. Climate data from 1963 to 2009 of 23 meteorological stations were used for current climate conditions. Downscaled outputs of two general circulation models were used to project future climate for the 2013-2040 and 2043-2070 periods, considering two contrasting scenarios of temperature and atmospheric CO2 concentration increase (high and low). Annual dry matter yield should be from 14 to 42% higher than the current one, depending on the evaluated scenario. Yield variation between seasons (seasonality) and years is expected to increase. The increase of dry matter accumulation will be higher in the rainy season than in the dry season, and this result is more evident for soils with low-water storage capacity. The results varied significantly between regions (60%). Despite their higher climate potential, warmer regions will probably have a lower increase in future forage production

Salmonella control within the pyramidal structured network of pigs' movements in France

Due to economical and public health consequences, control of Salmonella spread within pig herds is a major concern for the swine industry. A better understanding of the links between herds as well as between herds and slaughterhouses within a production stmcture is then needed to assess the effect of possible control measures at this level. In the French pork production chain, herds have specific links between them: some herds being animals suppliers for others. This organization induces a specific complex network in which the contacts between herds are hierarchized, dynamic and directed. We present here a modelling approach to assess the effect of control measure implementation on the Salmonella spread within the pyramidal structure of French pork production chain, coupled with the within-herd dynamics to represent the spread of Salmonella. Firstly, the susceptibility of the pyramidal organization to an external infection is tested. The number of infected herds at the end of the simulation is highly variable according to the initial infected herd (type of herd, level of the pyramid). Secondly, we assess the effect of a control measure implementation on the seroprevalence in groups of slaughter pigs. This measure, which consists in restricting animals' purchases according to the infectious status of herds combined with a reduction of within herd transmission of Salmonella, leads to decrease the number of highly contaminated herds. This modeling approach allows us to investigate the impact of control measures both at the within and the between-herds level.</p

Modelling as a tool to explore adaptation of Mediterranean sheep farming systems to climate change

International audienceMediterranean pastoral farming systems are increasingly subject to strong climatic constraints, which impact their access to grazing resources. To develop livestock farming systems adapted to climate change, combining resilientherds and an efficient use of various feed resources is central. Different combinations can be explored by modelling the impacts of climate change on feed resources and adaptation levers at the different levels of the farm organization(animal-herd-livestock system) however, this is methodologically challenging. This study aims at developing a simulation tool to represent, from animal to farm components, the multi-level implications of adaptation leversthat can be mobilized by Mediterranean small ruminant farmers. These levers can be related to animal biology and/or management strategies. The simulation tool enables to evaluate relative and combined effects of levers onfarm resilience and efficiency. It was developed with GAMA, an agent-based computer language, to allows the representation of each individual components (animals and areas) of the farming system. The simulator was calibratedon two contrasting pastoral sheep systems in the South of France: one grazing system uniquely based on rangelands and one complemented system with both rangelands and forage production. For these two contrasting situations, wetested the effects of three levers: (1) increasing the part of pastoral surfaces; (2) shifting the grazing periods; and (3) decreasing the flock size to better match with resources availability. The simulator was able to mimic the functioningof livestock farming systems and to evaluate for each situation the impact of adaptation levers on farm efficiency and resilience. Based on this prototype, other situations could be simulated according to climate change scenarios in theMediterranean area and adaptation levers could be explored to address specifically these challenges at the farming system level

Modelling as a tool to explore adaptation of Mediterranean sheep farming systems to climate change

International audienceMediterranean pastoral farming systems are increasingly subject to strong climatic constraints, which impact their access to grazing resources. To develop livestock farming systems adapted to climate change, combining resilientherds and an efficient use of various feed resources is central. Different combinations can be explored by modelling the impacts of climate change on feed resources and adaptation levers at the different levels of the farm organization(animal-herd-livestock system) however, this is methodologically challenging. This study aims at developing a simulation tool to represent, from animal to farm components, the multi-level implications of adaptation leversthat can be mobilized by Mediterranean small ruminant farmers. These levers can be related to animal biology and/or management strategies. The simulation tool enables to evaluate relative and combined effects of levers onfarm resilience and efficiency. It was developed with GAMA, an agent-based computer language, to allows the representation of each individual components (animals and areas) of the farming system. The simulator was calibratedon two contrasting pastoral sheep systems in the South of France: one grazing system uniquely based on rangelands and one complemented system with both rangelands and forage production. For these two contrasting situations, wetested the effects of three levers: (1) increasing the part of pastoral surfaces; (2) shifting the grazing periods; and (3) decreasing the flock size to better match with resources availability. The simulator was able to mimic the functioningof livestock farming systems and to evaluate for each situation the impact of adaptation levers on farm efficiency and resilience. Based on this prototype, other situations could be simulated according to climate change scenarios in theMediterranean area and adaptation levers could be explored to address specifically these challenges at the farming system level

Modelling temperature-dependent bionomics of Bemisia tabaci (Q-biotype)

The influence of temperature (17, 21, 25, 30 and 35 degrees C) on life-history traits of a Q-biotype Bemisia tabaci population on tomato is studied. Temperature-dependent relationships are characterized for immature developmental rate, immature survival, fecundity, longevity and intrinsic rate of increase. Development time vary from 20 days at 30 degrees C to 56 days at 17 degrees C and the lowest thermal threshold is estimated at 10.2 degrees C. The optimal temperature for immature development is 32.5 degrees C. Total fecundity (eggs per female) ranges from 105.3 (at 21 degrees C) to 41 (at 35 degrees C). The longevity decreases with temperature increase. The intrinsic rate of increase ranges from 0.0450 (at 17 degrees C) to 0.123 (at 30 degrees C). The functional relationships between temperature and life-history parameters are used to evaluate the effect of temperature on the population dynamics. Such mathematical relationships could provide a basis for future development of population models