Small scale outdoor pig systems in the tropics: Impacts on the soil, the physiological and the zootechnical responses of fattening pigs | Système porcin tropical en plein air et à faible densité : Conséquences sur le sol, les réponses physiologiques et zootechniques des porcs en croissance

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anglais. To our knowledge, there are few references on the pig production integrated into a mixed farming- system. In which farmers try to minimize inputs (in particular on feed purchase d). Feeding is one of the most important elements of the production cost. It is even more the case in tropical small countries, where the cost of the raw material included also the cost of transports. Farmers in these countries are looking for alternative solutions to reduce or replace the utilization of industrial concentrates, by the use of local resources (e.g. roots and tubers, sugar cane, banana). The main objective of this study was to compare fattening pigs’systems (outdoor vs. indoor, local vs. industrial feedings, local vs. exotic breeds). We performed two trials on a total of 54 fattening pigs, reared either in outdoor in a sweet potatoes field (n=18) or indoor with diet based on sweet potatoes (n=18) or indoor with industrial concentrates (n= 18). Our results show that the growth is significantly affected by the production system. The outdoor animals have a growth rate of 240 g/d, against 360 and 580 g/d for the indoor pigs fed with local or industrial feed, respectively (P < 0.001). Our findings on the physiological responses (blood profiles) highlighted the best adaptation of the local breed (Creole pig) when they passed from indoor to outdoor system. Indeed, adaptive hematologic response is faster in Creole pigs than in the exotic breed (Large White pigs). Unlike Creole pigs, the arrival of exotic pigs in outdoor conditions caused firstly a weakening of the hematologic status suggesting that Large White pigs are stressed by the change. Regarding the interaction between digging activities of pigs with macrofauna, in our experimental conditions (gradual discovery of plots and grazing period of 28 days), it seems that the presence of pigs on the plots (manure) is beneficial to soil macrofauna and thus the quality of the land from the farmer for future planting.The alternative systems (outdoor and/or diet based on local resources), although less powerful in a zootechnical point of view, should suit to mixed farmers who are looking for an economic gain on animal production by using crop residues and minimizing human interventions. These studies are the beginning of trials that aimed at meeting mixed farmers requirements in terms of techno-economic references on outdoor pig systems and alternatives to preserve and develop a niche market for the local pig breed.