H. Sahraoui*

M. Hachicha

Institut National de Recherche en Génie Rural Eaux et Forêts. Rue HédiElkarray, Elmenzah IV, Tunis, Tunisie

Abstract-Heavy metalssoil contamination near mining area is a serious problem for human health and the environment. The Lakhouat mine area (northwest-Tunisia-Siliana) was retained to analyze agricultural soil contamination by Pb, Zn and Cd. In situ measurements by portable XRF of Pb, Zn and Cd contents were performed on 133 samples points. The results obtained revealed a severe contamination of soil by Pb, Zn and Cd with up to 2766ppm average values for Pb, 12817ppm for Zn and 143ppm for Cd with a spatial variability depending on the land slope. Analysis of heavy metals showed high contents essentially in the surrounding area of tailing dams and that it is dispersed under the influence of water and wind erosion reaching agricultural land around the mine. The lowest soil quality was detected in areas near dams.

Keywords: mining site, heavy metals, XRF analysis, agricultural soil, soil quality

Résumé - La pollution métallique des sols à proximité des sites miniers constitue un grave problème pour la santé humaine et pour l’environnement. Le site Lakhouat (Siliana) a été retenu pour analyser la contamination des sols par le Pb, Zn et Cd. Tous ces éléments sont toxiques essentiellement à fortes doses. Des mesures in situ par l’appareil XRF des teneurs en Pb, Zn et Cd ont été réalisées sur 133 points. Les résultats obtenus ont révélé une forte contamination des sols en Pb, Zn et Cd avec des valeurs moyenne allant à 2766ppm pour le Pb, 12817ppm pour le Zn et 143ppm pour le Cd avec une variabilité spatiale selon la pente et depuis la digue. L’analyse des métaux lourds a montré de fortes teneurs en ces éléments essentiellement au voisinage des sources de contamination et que cette dernière se disperse sous l’influence de l’érosion hydrique et éolienne atteignant les sols agricole aux alentours de la mine. La plus basse qualité de sola été détectée dans les zones à proximité des digues.

Mots clés: Site minier, métaux lourds, analyse XRF, sol agricole, qualité du sol

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M. SALAH^1*

S. BOUDICHE¹

S. AMARA²

M. AMEUR³ 

S. BORNAZ¹

¹Ecole Supérieure des Industries Alimentaires de Tunis, ESIAT

²Direction Générale de l’Agriculture Biologique, DGAB

³Ecole Supérieure de l’Agriculture du Kef , ESAK

Abstract-Despite the importance of the dairy sector in Tunisia, the organic milk industry is still far from the expected rise and remains less developed than conventional milk. In this perspective, this study aims to highlight the difficulties and obstacles to the advancement of the sector and propose development strategies for the various links in this chain. To achieve this objective, a methodology based primarily on a value chain approach and an analysis of the value chain has been adopted.The results of the study show that organic milk is entering the Tunisian market conversion mode and the request exceeds 50% over the existing offer, a short chain related an interesting added value to all its stakeholders with a maximum leading to an interim and a specific sales channel obeying the skimming strategy.Furthermore, the study of production cost of organic milk shows that despite the constraints related to the lack of organic feed, to a much lower amount than that obtained by way of intensive production and administrative delays, the price of organic milk exceeds 53% conventional milk and comes to meet the consumers' purchasing power even if the investigation of the behavior of the latter shows that Tunisian consumersare ready to pay 25% extra for milk without chemical residue.Other shares, the action plan set up by the DGAB, scientific research breeders and processors manifested by capacity building, formulation of a balanced organic diet, cooperation between producers, extension of the required technical and targeted media following a defined marketing plan. This action plan has a valuable role in the development of organic milk industry for the preservation of future generations health and the environment therefore.

Keywords: Organic milk chain, value chain development strategy, consumer, Tunisia

Résumé - Malgré l’essor du secteur laitier en Tunisie et les performances atteintes en termes de quantités transformées, les enjeux de qualité et d’innovation demeurent très importants. La logique générale du développement à venir de cette filière consiste à la diversification de la gamme, le renforcement de la traçabilité qui constituent des axes de développement futurs. Ce développement se fera notamment à travers la valorisation par des signes de qualité, notamment l’appellation d’origine contrôlée et l’élevage biologique. A partir de ces produits, il est possible de créer de la valeur ajoutée notamment dans les zones de production. Le développement de l’élevage laitier biologique peut être privilégié dans les zones relativement isolées et dont les externalités physiques ne leur parviennent pas (transfert de pesticides/ herbicides provenant des autres productions). La présente étude vise à présenter l’état des lieux de la filière lait biologique résultant de la stratégie de promotion mise en place par la DGAB ces dernières années etde mettre en évidence ses forces et ses faiblesses avant de proposer des solutions aux difficultés rencontrées au niveau des différents maillons de cette filière.

L’analyse de la filière lait biologique au niveau de la production montre que les contraintes rencontrées se situent principalement au niveau du maillon de l’élevage en raison de la rareté des ressources d’aliments de bétails biologique (culture en mode extensif), de l’absence d’une ration alimentaire biologique locale équilibrée et de la dépendance de l’importation des aliments concentrés biologiques (à des coûts très élevés) constituant ainsi un handicap majeur à l’obtention de la certification. Par conséquent, le prix du lait biologique dépasse de 53% le lait conventionnel et n’arrive à satisfaire qu’une catégorie de consommateur à pouvoir d’achat très élevé.L’analyse de la chaine de valeur du lait biologique relative à une ferme pilote dans la région de Béja montre une chaine courte apportant une valeur ajoutée profitable à tous les acteurs de la filière.En revanche, les résultats de l’étude de marché montrent que le lait biologique a pu pénétrer le marché tunisien même en mode de conversion (en raison des difficultés pour obtenir la certification). En effet, la demande sur un marché spécifique, sis dans une banlieue de Tunis, à la Marsa, dépasse de loin l’offre potentiellefournie par quelques producteurs de lait biologique (estimée à 3000l/jour). Par ailleurs, la filière est capable de rapporter une valeur ajoutée intéressante à tous ses intervenants suivant un circuit de vente spécifique qui obéit à la stratégie d’écrémage.

Mots clés: Lait biologique, filière, chaine de valeur, consommateur, Tunisie

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M. Hadj Ayed*

M. Youneb

R. Bouras

Institut Supérieur Agronomique de Chott Mariem, Université de Sousse B.P 47.4042-Chott Mariem-Sousse-Tunisie

Abstract-The present study was conducted to investigate the effects of three different strategies to alleviate the negative incidence of heat stress on broilers: early acclimatation in chicks, feed restriction, beet betain feed inclusion (Betafin®: triméthyglycin, organic osmolyte improving osmotolérance) , broilers heat stressed from 22 to 35 days of age (35°C). A total of 496 chicks were used in the trial. Chicks were divided into four groups S, A, RS and B : (S) broilers were under heat stress (control), (A) acclimated group was exposed to 38 ° C (± 2 ° C) for 24 h at the 5^th day of age, (RS) was the lot subjected to a dietary restriction between 22^nd until the 35^th day and the batch (B) was supplied with a feed complement Betafin® (natural extract of Betain) from the 26^th day until the 35^th day. Each treatment was allotted randomly to four replications (31 chicks/replication). Controlled parameters are live body weight (BW), average daily gain ADG, feed intake (FI), feed conversion ratio (FCR) and mortality rate. Measures body temperature (TC), were performed on the stressed animals. At the end of the fattening trial 48 chickens (3broilers x 4replications x treatments) (35 days old) were slaughtered to study essentially, weights and yields of hot and chilled carcass, breast, thigh and wings. Betafin®, seems to be effective in improving the FCR (1.61), carcass yield and breast and wings’ weights. Early acclimation improved (p = 0.002), (FI) (93.72g ± 0.33) and BW (P = 0.0009) (1939.17g ± 8.03). It increases breast (367.04g ± 10.02), thighs (383.062g ± 0.66) and liver weights (1.82 ± 53097g). It lowers body temperature of 0.27 °C and (A) broilers were less susceptible to heat. Dietary restriction delayed the growth (P= 0.0009) and resulted in the lowest body weight at the end of the breeding (1738.23g ± 8.03). Mortality rate was not affected by the treatment. In conclusion, early acclimatization followed by the addition of Betafin® in the diet, both methods seemed to alleviate negative incidence heat stress on broilers.

Keywords: broiler, heat stress, performance, Betafin®

Résumé - Le présent travail consiste à évaluer l'impact de trois méthodes différentes pour atténuer les effets néfastes du stress thermique chez les poulets. Il s’agit de l'acclimatation précoce des poussins, de la restriction alimentaire et de l'incorporation de la Bétaïne végétale extraite de la betterave (Betafin®: triméthyglycine, osmolyte organique qui améliore l’osmotolérance) dans l'alimentation, sur les performances de poulets de chair exposés à l'âge de J22 à J35 à une température de 35°C. Quatre lots de poulets ont été constitués. Le lot sous stress thermique seulement (S), le lot acclimaté (A) subissant une acclimatation de 38°C (±2°C) pendant 24 h à J5, le lot soumis à une restriction alimentaire de J22 à J35et le lot (B) alimenté par la Betafin® deJ26 à J35. Chaque traitement est affecté à quatre répétitions de 31sujets chacun. L’humidité a été maintenue à 65% dans le bâtiment d’élevage. Les paramètres contrôlés sont: le poids vif (PV), le gain moyen quotidien (GMQ) et l'indice de consommation (IC). Des mesures de la température corporelle (TC) ont été faites au cours du stress thermique. A la fin de l'essai d'engraissement, un effectif de 48 (12x4) poulets âgés de 35jours, ont été abattus afin d'étudier essentiellement, les poids et les rendements respectifs du bréchet et de la cuisse. L'acclimatation précoce a contribué à l’amélioration de la consommation d'aliment (93,72g ± 0,33) (P=0,002) et le poids vif (1939g± 8,03) (P=0,0009). Elle accroît le poids du bréchet (367,4g ± 10,02), des cuisses (383,62g ± 0,66) et du foie (53,97g ± 1,82) (P≤0,0023). En outre, elle a permis de diminuer la température corporelle de 0,27°C et de rendre les poulets moins sensibles à la chaleur. La restriction alimentaire a décéléré le GMQ (P=0,0009) et a réduit PV final (1738g± 8,03). La Betafin®, est efficace (P=0,02), dans l'amélioration de la valorisation de l'aliment (IC=1,61), du rendement carcasse et du poids de bréchet et des ailes (P≤0,02). En conclusion, l'acclimatation précoce suivie de l'ajout de Betafin® dans l'alimentation, sont autant de méthodes qui ont donné les meilleurs résultats.

Mots clés: Poulet, stress thermique, performances, Betafin®

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A. GRICHI^1,2*

Z. NASR ²

M. L. KHOUJA ²

¹ Faculty of Sciences of Bizerta, 7021 Jarzouna, Tunisia

² National Institute for Research in Rural Engineering, Water and Forests Street Hédi Elkarray, Elmanzeh ІV, BP 10, Ariana 2080, Tunisia

Abstract-In this study, we investigated the chemical composition of volatile oil of Eucalyptus cinerea and its allelopathic effects on germination, seedling growth, chlorophyll content, net photosynthetic rate, transpiration and stomatal conductance of Sinapis arvensis, Erica vesicaria, Scorpiurus muricatus, Triticum durum, Vicia faba and Phaseolus vulgaris. Dose-response studies were conducted under laboratory and field conditions. Germination, seedling growth and net photosynthetic rates were greatly affected by E.cinerea essential oil. The reduction increased with increasing of essential oil concentration. Relative to the control, greatest reduction in net photosynthetic rate were observed at highest concentrations. The trend for transpiration in response to E.cinerea essential oil was similar to that exhibited by net photosynthetic rate except that the effects were greater in magnitude as compared to leaf photosynthesis.Stomatal conductance followed patterns similar to those observed for transpiration and leaf photosynthesis, however the effects were more apparent suggesting that closure of stomata might be an important factor for the decreases in photosynthesis and transpiration in this study. The test plants responded differently to eucalypt oil exhibiting a differential species-specificity. Indeed, the weeds were affected more strongly than the crops. The results indicated that E.cinerea essential oil could inhibit the growth and many physiological processes of tested species. Thus, E.cinerea possesses weed-suppressing abilities. Hence, these could be a base for developing natural herbicides.

Keywords: Allelopathy, Seedling growth, Net photosynthetic rate, Transpiration, Stomatal conductance.

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H. SBEI¹*

Z. HAMMAMI¹

Y. TRIFA¹

S. HAMZA¹ 

M. Cherif¹

¹ Institut National Agronomique de Tunis, 43 Av Charles Nicole, 1082 Cite Mahragene, Tunisie.

Abstract-Barley (Hordeumvulgare L.) is an important food and fodder cereal crop in Tunisia. While it’s highly affected by abiotic stress such us salinity. The latter restricts the use of agricultural land and limits the yield of barley. The development of salinity-tolerant crops is an important management option for maintaining production in salinity-deposited soils. 77 Doubled Haploid lines (DHs) produced from the cross between local accession 1a and Rihane were tested to evaluate the genetic variation and to identify salinity tolerant DHs in two contrasting environments; rain fed and irrigated with high water salinity (8.06 ms/cm). The trial was conducted in an augmented design model with six blocks and five modern cultivars as checks. The phenotypic evaluation was performed at anthesis and maturity stages. The agronomic traits performed at anthesis stage are: height (HA), leaf Area (LA), growth stage (GS) and dry matter of plants (DM). Number of spike (SN), thousand kernel weight (TKW), percentage of infertile spikelet’s (PIS) and biological yield (BY) are measured at maturity stage. Significant differences were observed among barley DH lines for all traits at salinity conditions.There was a wide range of variation in the response to salinity stress among the DHs. We observed a significant negative correlation between PIS and all others traits. The correlation coefficient between PIS and TKW is -0.56**. Whereas, significant positive correlations between DMand SN (r= 0.31). LA and DMare good indexes for screening for salinity tolerance at anthesis, and TKW and PIS at maturity stage.5 DHs showed a high TKW more than the parent Rihane. The difference in response to salinity stress among DH lines could offer elite alleles conferring salinity tolerance.

Keywords: Hordeumvulgare L., Contrasting Environments, Anthesis, Maturity, PIS, TKW.

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O. Maamouri^{1, *}

B. Jemmali²

M. Amrawi²

H. Selmi³

H. Rouissi²

¹ Regional Center of Agricultural Research Sidi Bouzid, 9100. Sidi Bouzid. Tunisia

² Laboratory of Improvement and Integrated Development of Animal Productivity and Food Resources, Higher School of Agriculture of Mateur, University of Carthage, Tunisia.

³ Regional Filed crops Research Center Beja, Tunisia

Abstract - The objective of this study was to investigate the effects of yeast Saccharomyces cerevisiae feed supplement on lambs growth and their feed intake. For this trial, 14 lambs aged of 148 days were used during 9 weeks and allocated to 2 groups according to body weight and age. Lambs received a basal diet of oat hay ad libitum supplemented with whole grain barley (400g) and concentrate (400g). The control group (C) received oat hay ad libitum, whole grain barley (400g) and concentrate (400g). The second group (Y) received the same feeds as the C group in addition to 1,5g/lamb/day of yeast Actisaf ® Sc 47. The ration was distributed twice a day at fixed times. Animals had free access to water. Results indicated that the average amount of oat hay voluntarily ingested was 147,1 and 148,7 g DM/lamb/day, for C and Y groups, respectively in the first week of control. Feed intake increased slightly until the 5^th week and reached a maximum around the 9^th week of trial (374,6 vs. 439,9 g DM/lamb/day for C and Y groups, respectively). Weight of lambs evolved during the trial period, it increased from 22,5 kg to 30,5 kg for C group and 22,3 kg to 34,5 kg for Y group with a notable superiority for Y lambs compared to C animals. For the daily gain, the respective averages are 145 g/day and 223 g/day for lambs of C group and Y one. There significant differences for daily gain (g/day) within 5^th, 6^th, 8^th weeks and throughout the whole growth trial (1^th; 8^th week). Feed conversion decreased notably for lambs of Y group For Facies fermentation parameters (digestibility organic matter (OMD), metabolisable energy (ME), volatils fatty acids (VFA) and nitrogen ammonia (NH3-N)) did not reveal significant differences from yeast addition (P> 0.05).

Keywords: lambs/ concentrate/ Saccharomyces cerevisiae/ growth/ rumen/ gas production.

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