L'ELEVAGE OVIN EXTENSIF EN TUNISIE : DISPONIBILITES ALIMENTAIRES ET INNOVATIONS POUR LA VALORISATION DES RESSOURCES FOURRAGERES LOCALES

N° ISBN - 978-2-7380-1284-5International audienceSheep farming plays a vital role in food safety in Tunisia. This paper aims to reflect the current status of sheep farming through an analysis of their food availability and limits. A study of the possibilities for improving the local feeding resources is then made identifying the innovations in this field. Results show that the decrease in pasture areas is caused by the over-grazing, the frequent droughts and the expansion of cereal crops and tree plantations. Use of concentrates becomes more frequent in livestock industry. These concentrates are heavily based on imported ingredients whose prices have tripled over the last two decades. Consequently, a renewed interest has been given to the use of local feed resources and looking for alternatives such as their partial or total replacement of the imported raw materials. The use of the local barley and field beans in the sheep feeding could ensure acceptable animal performances. In the arid and semi-arid Tunisian zones, thousands of hectares of fodder shrubs have been established, especially spineless cactus, Atriplex nummularia and Acacia cyanophylla. Other innovations in animal feeding demonstrated the effectiveness of alternative feed resources like using feed blocks which could represent a promising nutritional tool especially when animals are grazing on poor pastures, the use of multi-purpose shrubs, or several agricultural and agro-industrial by-products (treated straws, cakes, pulps...). A lack of adequate co-ordination and synergy between the different stakeholders is inhibiting the progress and implementation of transversal approaches that are necessary for the delivery of integrated sustainable policies

Synthesis of MCM-41 nanomaterial from Algerian bentonite: influence of synthesis pH

Mesoporous materials of the MCM-41 type were synthesized from Algerian bentonite as an aluminosilicate source without the addition of pure silica and aluminum reagents. The samples were synthesized under hydrothermal condition using cetyltrimithylammonium bromide (CTAB) as surfactant. The influence of initial synthesis pH on the material properties of as-synthesis MCM-41 samples was studied at different temperatures of crystallization. The samples were characterized using several techniques e.g. X-ray diffraction (XRD), N2 adsorption-desorption and transmission electron microscope (TEM). The experimental results showed that bentonite can be used as an aluminosilicate source for the synthesis of Al-MCM-41. By decreasing the synthesis temperature of crystallization, it is necessary to decrease the synthesis pH value to form the best ordered hexagonal phase and eliminate the lamellar phase.Keywords: bentonite; alkaline fusion; pH; Al-MCM-4

Toxicity and neurophysiological impacts of three plant-derived essential oils against the vineyard mealybug Planococcus ficus

Many natural products are able to control pests and can be used as alternatives for chemical treatments. Plant essential oils (EOs) have been found to exhibit some biological activity against many insects including mealybugs. This study aimed at studying the insecticidal activity and behavioral and neurophysiological impacts of three plant essential oils against the vine mealybug Planococcus ficus. The topical and fumigant toxicity of Cymbopogon citratus, Mentha piperita, and Pelargonium graveolens essential oils was evaluated against P. ficus adults. The chemical composition analysis of EOs by gas chromatographic-mass spectrometry (GC-MS) revealed citronellal (31.69 %), menthol (73.78 %), and geraniol (39.6%), as major components, respectively. Bioassays of EOs against vine mealybug adults through fumigation toxicity method revealed lethal concentrations LC50 values of 17.01, 26.27 and 24.52 µL·L-1 air for C. citratus, M. piperita, and P. graveolens, respectively. In both topical and fumigant bioassays, essential oil from C. citratus was the most active altering the behavioral response of treated mealybugs which becomes hyperactive and disoriented. EOs induced general stress in P. ficus adults, as evidenced by oxidative stress biomarker analyses. Biochemical analyses showed that the EOs exposure reduced the activity of acetylcholinesterase and significantly induced the glutathione S-transferases and Malondialdehydes accumulation in the vine mealybug tissues. Mortality caused by lemongrass EO positively correlated with the significant decrease in the AChE activity indicating lethal neurological effects. These toxicity bioassays and neurological impact findings provide new informations for formulating effective essential oil based-insecticides to control P. ficus in the framework of integrated pest management programs

Pulsed 86Sr-labeling and NanoSIMS imaging to study coral biomineralization at ultra-structural length scales

A method to label marine biocarbonates is developed based on a concentration enrichment of a minor stable isotope of a trace element that is a natural component of seawater, resulting in the formation of biocarbonate with corresponding isotopic enrichments. This biocarbonate is subsequently imaged with a NanoSIMS ion microprobe to visualize the locations of the isotopic marker on sub-micrometric length scales, permitting resolution of all ultra-structural details. In this study, a scleractinian coral, Pocillopora damicornis, was labeled 3 times with 86Sr-enhanced seawater for a period of 48h with 5days under normal seawater conditions separating each labeling event. Two non-specific cellular stress biomarkers, glutathione-S-transferase activity and porphyrin concentration plus carbonic anhydrase, an enzymatic marker involved in the physiology of carbonate biomineralization, as well as unchanged levels of zooxanthellae photosynthesis efficiency indicate that coral physiological processes are not affected by the 86Sr-enhancement. NanoSIMS images of the 86Sr/44Ca ratio in skeleton formed during the experiment allow for a determination of the average extension rate of the two major ultra-structural components of the coral skeleton: Rapid Accretion Deposits are found to form on average about 4.5 times faster than Thickening Deposits. The method opens up new horizons in the study of biocarbonate formation because it holds the potential to observe growth of calcareous structures such as skeletons, shells, tests, spines formed by a wide range of organisms under essentially unperturbed physiological condition

Prise en charge du couple mère enfant de la varicelle pendant la grossesse

La varicelle est une maladie généralement bénigne chez l’enfant, cependant l’atteinte de l’adulte est potentiellement grave et son association à la grossesse expose la mère et le nouveau né à des risques de complications plus redoutables.La prise en charge multidisciplinaire associant obstétricien, biologiste et pédiatre est indispensable pour limiter les effets délétères de l’infection par la varicelle pendant la grossesse.Nous rapportons dans cet article les approches thérapeutiques actuellement proposées pour la prise en charge anté et péripartum du couple mère-enfant en cas d’infection par la varicelle pendant la grossesse et nous proposons des conduites visant à atténuer les complications maternelles

Plant Genetic Resources and Germplasm Use in India

Plant genetic resource (PGR) scientists now recognize the importance of shifting from a singular focus on conservation to a focus on both conservation and utilization of germplasm in order to meet future challenges. This paper analyzes the patterns of distribution of pearl millet, six small millets, chickpea and pigeonpea germplasm over the last 10 years at the two major genebanks functioning in India: the National Genebank at the National Bureau of Plant Genetic Resources (NBPGR) and a Consultative Group for International Agricultural Research (CGIAR) Genebank at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), as well as the patterns of use of germplasm by millet breeders in India. Between the years of 1999-2009, ICRISAT distributed approximately 48 per cent of all its collections to breeders in India whereas NBPGR distributed 36 per cent of their collection. A total of 20 responses (30 per cent of surveys sent) were collected through this study. Sixty-five percent of respondents said that they rarely (<50 per cent of the time) use germplasm from genebanks in their breeding programs. It is important that both genebanks look into several issues in order to improve levels of distribution and utilization, collection, duplication, engagement of the private sector, access to information, and pre-breeding