TEŽINSKO–DUŽINSKI ODNOS 57 RIBLJIH VRSTA U RIJEKAMA JUGOISTOČNOG DIJELA OBALE BJELOKOSTI

Weight–length relationships (WLR) of 57 fish species belonging to 22 families from the coastal rivers of the south–eastern of Ivory Coast were studied. Samples were collected with two fleets of monofilament gill nets. The value of the exponent b in the WLR (W=aLb) ranged from 2.213 to 3.729. The mean and the median values were 2.892 and 2.899 respectively, whereas 50% of the value ranged between 2.787 and 3.048. For 11 species, these relationships are described for the first time for this sub–region.U radu je istraživan težinsko–dužinski odnos (WRL) 57 vrsta riba koje su pripadale 22–dvjema porodicama, a koje se nalaze u rijekama jugoistočnog dijela Obale Bjelokosti. Uzorci su sakupljeni dvjema vrstama mreža. Vrijednost eksponenta b u WRL (W=aLb) kretao se između 2,213 i 3,729. Prosječna i srednja vrijednost bile su 2,892, odnosno 2,899, dok je 50% te vrijednosti bilo između 2,787 i 3,048. Za 11 vrsta ti su odnosi opisani prvi put u ovoj podregiji

Typologie des granitoïdes de la région de Tiassalé (Sud de la Côte d’Ivoire - Afrique de l’Ouest) : Structurologie et Relations Génétiques

L’étude petro-structurale a permis de caractériser, en partie, les différents faciès des granitoïdes de la région de Tiassalé (Sud de la Côte d’Ivoire). Les treize (13) faciès granitiques inventoriés sont les suivants :1) granodiorite, 2) granite à feldspaths alcalins, 3) granite alcalin à deux micas, 4) granite à biotite, 5) syéno-granite, 6) monzonite quartzique, 7) monzonite à biotite, 8) syénite quartzique, 9) granite monzonitique, 10) granite fin métamorphisé (granite gneissique), 11) tonalite, 12) leucogranite, 13) granite aplitique à biotite. La chronologie relative établie entre ces granitoïdes est la suivante : le granite à feldspaths alcalins (du site TIA 2) est antérieur au syénogranite du même site, lui-même antérieur au granite à biotite (des sites TIA 2c et TIA 3a) qui est antérieur au granite à deux micas (du site TIA 2b). Aussi, le granite à biotite est antérieur à la monzonite quartzique (du site TIA 3b). Les tonalites (site TIA 4c) sont antérieures au granite alcalin du même site. La monzonite à biotite (du site TIA 6) est antérieure au granite à biotite (du site TIA 5a).Les déformations sont essentiellement représentées par : 1) des filons de directions N00°, N10°, N60°, N80°, N90°, N110°, N130° et N150° ; 2) des fractures décrivant des décrochements dextres ou senestres de direction N30°, N50°, N60° et N120° ; 3) une foliation locale, subverticale de direction N130° ; 4) une stratification de direction N30° dans les micaschistes du Bandama ; 5) des schistosités de direction N80° dans les micaschistes du Bandama ; 6) une shear zone de direction N50° ; 7) des schistosités de directions variables dans les granitoïdes : N10° , N20°, N30°, N60° et N130°. L’absence dans la région de gneiss et de migmatites, la présence d’enclaves de nature pétrographiques variées dans les différents faciès étudiés, militent en faveur de l’hypothèse d’une origine mantellique ou mixte pour ces faciès granitoïdiques.Mots-clés : typologie, granitoïdes, structurologie, relations génétiques, Tiassalé, Côte d’Ivoire, Afrique de l’Ouest

Incorporation du coprah et des cuticules de cacao et d’arachide dans l’aliment du (tilapia du nil( (Oreohromis niloticus, linné, 1758) eleve en etang : Effet sur la croissance et la composition biochimique

Dans le but de réduire le coût de l’alimentation du tilapia en élevage, quatre aliments exogènes pulvérulents dont un industriel (Ivograin) servant de référence (AR) et trois tests locaux (A1, A2 et A3) formulés uniquement à base de sous-produits locaux ont été utilisés. La composition de base des aliments tests est : A1 (cuticules de de fève de cacao, son de maïs, tourteaux de soja et coton) ; A2 (cuticules de graine d’arachide, son de maïs, tourteaux de soja et coton) et A3 (tourteaux de coprah, soja et coton et son de maïs). Tous les aliments titrent environ 28 % de protéines. L’expérience est conduite à la ferme « Blondey » (Côte d’Ivoire) sur des juvéniles de Oreochromis niloticus d’un poids initial de 33,3 ± 0,4 g. Des juvéniles ne recevant pas d’aliment exogène ont servi de lot témoin (At) pour apprécier l’effet de l’aliment endogène. La densité de stockage était de 2 poissons/m2. Trois étangs par traitement ont été utilisés. La ration journalière a été distribuée à 9 h et à 15 h. Après 180 jours d’expérience, les poids moyens finaux ont atteint des valeurs respectives de 273,42 ± 26g ; 295,08 ± 18,5 g ; 352,1 ± 20,7g ; 309,38 ± 22,3 g et 101,06 ± 4 g pour A3, A2, A1, AR et At. Au niveau des aliments exogènes, le meilleur quotient nutritif (Qn= 2,22) et de croissance journalière (1,77 g/jour) ont été obtenus avec A1. Le plus grand Qn (2,88) et la plus faible croissance journalière (1,33g /jour) sont enregistrés avec A3. La comparaison de tous les lots indique que la plus faible croissance (0,38 g/jour) est enregistrée chez les poissons non nourris à l’aliment exogène (At). Les lipides corporels (16 - 17 %) sont plus élevés chez les poissons nourris aux aliments tests que ceux des lots de référence (14 %) et témoins (13 %). Par rapport à l’aliment AR, les aliments tests réduisent le coût de revient de l’aliment et le coût de l’alimentation par unité de prise de poids de 15 - 18 % et 3,1 - 27,4 %, respectivement.Mots clés : Aliments, arachide, cacao, coprah, cuticules, Oreochromis niloticusEnglish AbstractIncorporation of coconut oil cake, cocoa bean shell and peanut skin in diet for nile tilapia (Oreohromis niloticus, linné, 1758) reared in pond : Effect on growth and biochemical compositionIn order to reduce feeding cost of rearing tilapia, four powdered diets including an industrial product (Ivograin) (as reference = AR) and three practical diets (A1, A2 and A3) formulated using local by-products were used. Formulated diets were designated as A1 (cocoa bean shell, corn bran, soybean oil cake, cottonseeds oil cake, premix), A2 (peanut skin, corn bran, soybean oil cake, cottonseeds oil cake, premix) and A3 (corn bran, soybean oil cake, cottonseeds oil cake and coconut oil cake). The four diets contained approximately 28 % crude protein. The experiment was carried out at farm « Blondey » (Ivory Coast) on fingerlings Oreochromis niloticus with an initial body weight of 33.3 ± 0.4g. In addition, fingerlings non-fed with exogenous diet were used as control group to assess the impact of the natural food. The used stocking density was 2 fish/m2. Three replicate ponds were assigned to each of the treatment. Fish were fed twice daily (9.00 h and 15.00 h). After 180 days of experiment, the final body weight observed were respectively 273.42 ± 26 ; 295.08 ± 18.5 ; 352.1 ± 20,7 ; 309.38 ± 22.3 g and 101.06 ± 4 g for A3, A2, A1, AR and At. Considering the four diets (A1, A2, A3 and AR), the best daily weight gain (1.77 g/day) and feed conversion ratio (2.22) were obtained with A1 which were significantly different (p < 0.05) from values obtained for the other groups. The poorest weight gain (1.33 g/day) and the highest feed conversion ratio (2.88) were recorded for A3. The comparison of all groups (A1, A2, A3, AR and At) revealed that the poorest value of the daily weight gain (1.33 g/day) was recorded for the control group (At). Fat deposition was highest (16 - 17 %) in fish fed practical diets, while fish fed diets AR and control fish (At) recorded respectively (14 %) and (13 %). Practical diets reduced the feed cost and feeding cost per unit of weight gain by 15 - 18 % and 3.1 - 27.4 %, respectively.Keywords : Diets, peanut skin, cocoa bean shell, coconut oil cake, Oreochromis niloticu

Effect of diets containing cocoa bean shell and coconut oil cake on the growth of Oreochromis niloticus (LINNE, 1758) in pond

A 180-day feeding trial was conducted at fish farm ‘’Blondey‘’ (Côte d’Ivoire) with Nile tilapia, Oreochromis niloticus (LINNE, 1758) to evaluate the effect of cocoa bean shell and coconut oil cake on its growth. Juvenile tilapia (mean weight of 33.16 ± 2.2 g) was fed with a commercial diet (Ivograin) and two formulated diets twice daily (09.00 h and 15.00 h). The used stocking density was 2 fish/m2. Formulated diets were designated as D1 (cocoa bean shell, corn bran, soybean oil cake and cottonseeds oil cake) and D2 (coconut oil cake, corn bran, soybean oil cake and cottonseeds oil cake). All the tested diets contain around 28% protein and each diet was randomly assigned to triplicate ponds to evaluate growth, feed utilization, body composition and cost benefit. Fish fed diet with D1 gave the highest daily weight gain (1.94 ± 0.30 g/day) and the best feed conversion ratio (2.01). The lowest daily weight gain (1.53 ± 0.32 g/day) and the highest feed conversion ratio (2.47) were recorded for diet D2. Tilapia fed with diet D2 and commercial one (Ivograin) displayed similar growth and feed efficiencies patterns. Lipid accumulation was higher in fish reared with diets D1 and D2 compared to reference diet (Ivograin). Diets D1 and D2 reduce feed costs per unit of weight gain by 34.44 and 19.47%, respectively, compared to commercial diet.Keywords: Oreochromis niloticus, feeding, cocoa bean shell, coconut oil cake, growth, Côte d’Ivoire

Activite Photosynthetique Du Phytoplancton Dans Le Barrage Hydroelectrique D\'ayame I (Côte D\'ivoire)

L\'activité photosynthétique du phytoplancton du barrage hydroélectrique d\'Ayamé I a été suivie au cours de six campagnes de mesures sur deux stations (Bakro, Ayamé) afin d\'évaluer son évolution spatio-temporelle et d\'identifier les variables qui la contrôlent. Les mesures de la productivité photosynthétique du phytoplancton ont été effectuées dans la couche euphotique (0-3 m). Les résultats montrent une variabilité temporelle de l\'activité photosynthétique dans les deux stations du lac. Les productivités phytoplanctoniques sont maximales à Bakro et à Ayamé en début de saison des pluies (respectivement 0,35 et 0,81 mg.C.m-2.j-1) et minimales en saison sèche (respectivement 0,18 et 0,43 mg.C.m-2.j-1). Les productivités phytoplanctoniques ont été positivement corrélées aux nitrates (r > 0,8 ; p 0,6 ; p < 0,05), ce qui souligne l\'importance des nutriments dans la productivité du phytoplancton.Photosynthetic activity of phytoplankton in the hydroelectric reservoir of Ayamé I was studied during 6 data acquisition campaigns at two stations (Bakro, Ayamé). The main objective was to monitor spatial and temporal changes in phytoplankton productivity and identifiy potential variables responsible for the changes. Phytoplankton photosynthetic activity was determined in the euphotic layers (0-3m) of the lake. Results show changes in photosynthetic activity with time in the two stations. Maximum concentrations of carbon assimilation were observed during the begining of the rainy season (0.35 and 0.81 mg.C.m-2.j-1 ) and minimum activity during the dry season (0.18 and 0.43 mg.C.m-2.j-1) at Bakro and Ayamé, respectively. The phytoplankton productivities correlated with nitrate (r > 0.8 ; p 0.6 ; p < 0.05) which underscores the importance of nutrients in phytoplankton productivity. Keywords: Activité photosynthétique, phytoplancton, barrage hydroélectrique, Côte d'Ivoire.Agronomie Africaine Vol. 19 (1) 2007: pp. 63-7

Efficacy of the association of cover crops with maize and direct sowing short-term effect on crops? yields in maize-cotton cropping system in Western Burkina Faso.

To improve the productivity and sustainability of cotton and cereals based system, direct sow ing under mulch was tested for its efficacy on cotton and maize yields on the research station of Farako - Bâ, in Western Burkina Faso. The experimental design was a complete randomized blocks of Fisher with four replications. Conventional tillage by annual moldboard plowing (T7) was compared with direct sowing under mulch -based cropping system (DMC) using maize association with cover crop s defined as: maize without cover crop (T1), maize +Brachiaria ruziziensis(T2), maize + B. ruziziensis+ Mucuna cochinchinensis (T3), maize + B. ruziziensis+ Panicum maximum (T4), maize + B. ruziziensis + Stylosantes hamata (T5), and maize + Crotalaria juncea (T6). Cover crops were planted 21 days after maize emergence between the rows of this main crop. The biomass produced by the cover crops and maize straws were evaluated as well as maize and cotton yields, during the first 6 years of the study, from 2010 to 2015. Results showed that among cover crops, the biomass production was significantly lower with C. juncea. The associations of cover crops with maize increased significantly the production of total dry matter compared to plots without cover crops, in the conventional tillage. Association with cover crops did not influence significantly nitrogen, phosphorus and potassium contents of maize and the maize’s yields even if the depressive effects were recorded. Compared to the conventional tillage, the DMC appeared also effective on seed cotton yields even without a significant improvement during the 6 first years of the study . These promising results, confirm the feasibility in tropical conditions of DMC which must be continued to better analyze its long-term effects on soil properties

Production de Oreochromis niloticus avec des aliments à base de sousproduits agricoles

Des alevins de Oreochromis niloticus (0,7 ± 0,06 g) ont été nourris dans seize étangs avec quatre aliments dont trois aliments tests (A1, A2 et A3) formulés uniquement à base de sous-produits agricoles. La composition de ces aliments tests est la suivante : A1 (tourteaux de soja, de coton, sons de maïs et de mil) ; A2 (tourteaux de soja, de coton, sons de maïs et de riz) et A3 (tourteaux de soja, de coton, sons de mil et de riz). Le quatrième (At), contenant de la farine de poisson, est un produit industriel et a servi de témoin. Deux densités de mise en charge (10 et 13 ind./m2 ) ont été appliquées pour chaque traitement alimentaire. Chaque densité d\'élevage a été répliquée une fois. Après 120 jours d\'élevage, tous les poissons ont atteint au moins 25 g (poids seuil de sexage). Les meilleures performances zootechniques sont obtenues avec l\'aliment A1, suivi de l\'aliment A2. Les poids moyens finaux observés aux densités 10 et 13 ind./m2 sont de 54,69 ± 7,76 et 46,77 ± 5,87 g (A1), 46,32 ± 6,71 et 41,23 ± 5,32 g (A2) ; 40,90 ± 7,64 et 37,31 ± 5,73 g (A3) puis de 41,72 ± 6,57 et 37,45 ± 5,84 g (At). Les quotients nutritifs respectifs correspondants sont de 1,13 ; 1,30 ; 1,87 et 1,72 (10 ind. /m2), puis de 1,40 ; 1,63 ; 1,74 et 1,80 (13 ind. /m2). Les aliments A1 et A2 permettent un niveau de production supérieur à celui du témoin. Comparés au témoin, des taux de réduction respectifs de 30 % et d\'environ 14 à 37% des coûts des aliments tests et de production des fingerling ont été obtenus..Alevins of Oreochromis niloticus (0.7 ± 0,06 g) were fed with three test diets (A1, A2 and A3) formulated using agricultural by-products and a commercial one containing fish meal (control diet = At). The composition of these test diets is: A1 (oilcakes of soy, of cotton, bran of corn and of millet); A2 (oilcakes of soy, of cotton, bran of corn and of rice) and A3 (oilcakes of soy, of cotton, bran of millet and of rice). Two stocking densities (10 and 13 ind. / m2) were applied for each experimental diet. At the end of 120 days of rearing, all experimental fish reached more than 25g (doorstep weight for manual sexing). Diets A1 and A2 displayed the better growth and food utilization performances. Final mean weight of fish at stocking densities 10 and 13 ind. / m2 respectively, ranged from 54.69 ± 7.76 to 46.77 ± 5.87 g (A1), 46.32 ± 6.71 to 41.23 ± 5.32 g (A2); 40.90 ± 7.64 to 37.31 ± 5.73 g (A3) and 41.72 ± 6.57 to 37.45 ± 5.84 g (At). The corresponding food conversion rates were 1.13; 1.30; 1.87 and 1.72 (10 ind. /m2), then 1.40; 1.63; 1.74 and 1.80 (13 ind. /m2). Test diets A1 and A2 produced more yield than the control one. Relatively to the assessment economic aspect, test diets reduce the diet cost and fingerlings production cost, respectively of rate about 30 % and 14 to 37 %, compared to that of the control diet. Keywords: Oreochromis niloticus, feeding, agricultural by-products, production, Côte d\'Ivoire.Sciences & Nature Vol. 5 (1) 2008: pp. 89-9

Combination of dictionary learning by K-SVD and a colorimetric texture descriptor for improved identification of geological structures : Case of rocks

In this paper, we propose a new representation of characteristics based on texture and color analysis for rock recognition. The proposed method combines the discriminating colour and texture characteristics of a rock image from a composite LBP descriptor to make automatic, fast and efficient rock identification. Indeed, the colorimetric texture descriptor ALBPCSF (Adjacent Local Binary Pattern based on Color Space Fusion) derives from the concatenation of the LBP texture characteristics and the color characteristics with the fusion of the two (02) colorimetric spaces RGB and HSV. In our methodology we first applied ALBPCSF on images of two (02) different families of rocks that are magmatic rocks and metamorphic rocks to produce colorimetric texture images then the K-SVD (K-Singular Value Decomposition) dictionary algorithm with a choice of suitable parameters is applied to said texture images produced to calculate a signature of the rocks from our image base. For dictionary learning the K-SVD method uses Orthogonal Matching Pursuit (OMP) as a sparse coefficient coding algorithm. The experimental results of the proposed approach on our image database show that the results of the proposed color LBP are relatively better than those with a grayscale or scalar LBP on the one hand and better than those of the direct K-SVD on the initial images on the other hand. The proposed strategy contributes significantly to improving the performance of automatic rock identification systems

Study of oxygen evolution reaction on thermally prepared xPtOy-(100-x)IrO2 electrodes

The mixed coupled xPtOy-(100-x)IrO2 electrodes (x = 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100) were thermally prepared at 450 °C on titanium supports. The prepared electrodes were firstly physically characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Afterwards, electrochemical characteri­zations were performed by voltammetric (cyclic and linear) methods in different electrolyte media (KOH and HClO4). It is shown that the prepared electrodes are composed by both PtOy (platinum and platinum oxide) and IrO2 (iridium dioxide). For xPtOy-(100-x)IrO2 electrodes having higher content of IrO2, more surface cracks and pores are formed, defining a higher surface area with more active sites. Higher surface area due to presence of both PtOy and IrO2, is for xPtOy-(100-x)IrO2 electrodes in 1 M KOH solution confirmed by cyclic voltammetry at potentials of the oxide layer region. For all prepared electrodes, voltammetric charges were found higher than for PtOy, while the highest voltammetric charge is observed for the mixed 40PtOy-60IrO2 (x = 40) electrode. The Tafel slopes for oxygen evolution reaction (OER) in either basic (0.1 M KOH) or acid (0.1 M HClO4) media were determined from measured linear voltammograms corrected for the ohmic drop. The values of Tafel slopes for OER at PtOy, 90PtOy-10IrO2 and IrO2 in basic medium are 122, 55 and 40 mV dec-1, respectively. For other mixed electrodes, Tafel slopes of 40 mV dec-1 were obtained. Although proceeding by different OER mechanism, similar values of Tafel slopes were obtained in acid medium, i.e., Tafel slopes of 120, 60 and 39 mV dec-1 were obtained for PtOy, 90PtOy-10IrO2 and IrO2, and 40 mV dec-1 for other mixed electrodes. The analysis of Tafel slope values showed that OER is more rapid on coupled mixed electrodes than on pure PtOy. For mixed xPtOy-(100-x)IrO2 electrodes, OER is more rapid when the molar percent of PtOy meets the following condition: 0 ˂ x ≤ 80. This study also showed that the mixed coupled electrodes are more electro­cata­lytically active for OER than either PtOy or IrO2 in these two media. </p