Courbes de lactation des caractères laitiers selon la saison de vêlage chez les vaches laitières Frisonne-Holstein en Tunisie

M. KHALIFA^1*,

A. HAMROUNI¹

M. DJEMALI¹

¹ Animal Genetic Resources and Feed Resources Research Lab: National Agronomy Institute- Tunis, 43 Avenue Charles Nicolle, Tunis 1082

Abstract – The effect of month or season of calving on production traits has been reported in dairy cattle as a main source of variation of milk traits. The dairy cow produces differently in relation to the period of calving. The shape of its lactation curve based on seasonal effects represents a reliable tool to evaluate its adaptation to climate variation within and across years. The objectives of this study were to: 1) identify the major environmental and non-genetic factors of Holstein production traits under Southern Mediterranean breeding systems and 2) describe their milk performances (lactation curve, fat and protein amounts) according to calving season. A total of 836.901 daily tests of 67.137 Friesian Holstein, recorded in 2885herds from 2003 to 2015, were used in this study. A linear model was developed including Herd daily-test, farm ownership, month of calving, year of calving, lactation number, year of control, age of calving and daily-test control number. Least square solutions of month of calving allowed to identify 3 different seasons of calving with season 1 including five months (September to January), season 2 including four months (February to May) and season 3 including Summer months. The same linear model was used within season. Main results showed that daily herd-test, month of calving, year of calving, lactation number, year of control, age of calving and test control number were all significant sources of variation for milk, fat and protein amounts. Average daily performances for milk, fat and protein yield, fat and protein percent were 18.51± 8kg/d; 0.67 ± 0.30kg/d; 0.59± 0.25 kg/d; 3.63%± 0.74 and 3.18±0.40%, respectively. The trends of the lactation curves showed that the cows that calved during autumn and winter produce more milk during all lactation than those which calved in spring and summer.

Keywords: Holstein, curve, lactation, season, calving.

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Influence de porte greffes tolérants au virus de la Tristeza sur le comportement de la variété "Hernandina" de clémentinier (Citrus clementina L) vis à vis du sel

H. ASKRI^1*

A. NAJAR²

 S. HADDAD³

 H. SNOUSSI⁴

 S. REJEB¹

¹ Laboratoire de Valorisation des Eaux Non Conventionnelles, Institut National de Recherches en Génie Rural, Eaux et Fôrets, Université de Carthage, Rue Hedi Karray, 1004 El Menzah, Tunisie

² Laborataoire de Protection des Plantes, Institut National de Recherche Agronomique de Tunis, Université de Carthage, BP. 10 Rue Hedi Karray, 1004 El Menzah, Tunisie

³ Institut Supérieur de Biotechnologie de Sidi Thabet, BP. 66, 2020, Sidi Thabet, Tunisie

⁴ Laborataoire d’Horticulture, Institut National de Recherche Agronomique de Tunisie, Université de Carthage, Rue Hedi Karray, 1004 El Menzah, Tunisie

Abstract – This work aims to study the response of Clementine var. Hernandina grafted on five rootstocks (Sour orange, Citrange C35, Citrange Carrizo, Citrumelo Swingle and Volkamer Lemon) during the vegetative growth stage at different salinity levels through morpho-physiological analyses. An experiment was performed under controlled conditions on 18-month-old plants. Salt was gradually supplemented by increase of 15 to 20 mM NaCl to the nutrient solution until reaching concentrations of 35 and 70 mM NaCl, applied for 16 weeks. Parameters analyzed were related to growth, water relations, mineral nutrition, and chlorophyll contents. Salt induced foliar chlorosis and necroses, particularly on Hernandina grafted on C35 and Citrange Carrizo. Independently of the rootstock, salt stress adversely affected plant growth parameters and shoot parts decreased more than root ones. Na⁺intrusion induced cationic disturbances and chlorophyll contents reductions. Deleterious effects were more pronounced in Citrange C35, Citrange Carrizo and Citrumelo Swingle, considered as sensitive rootstocks, compared to Volkamer lemon and Sour orange which are ranked as tolerant ones.

Keywords: salt stress, citrus, rootstock, mineral nutrition, chlorophyll contents.

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K. Kadri*¹

B. Kods²

M. Souhayla¹

¹ Laboratoire de Biotechnologie et Ressources génétiques de palmier dattier, Centre régional de recherches en agriculture oasienne, BP :62, 2260 Degache, Tunisie.

² Faculté des sciences de Gafsa, campus Universitaire Sidi Ahmed Zarroug -2112 Gafsa, Tunisie.

Abstract – In Tunisia, the cultivation of the date palm is the pivot of the agricultural activity of the regions of South West and particularly in the areas of Djerid and Nefzaoua. It constitutes the framework of the oases which are unique sources of greenery and life in the middle of the desert. The cultivators of the date palm were able to deduce the importance of the origin of the pollen used on the quantity and the quality of the production of the dates. Consequently, they use selective pollinating male varieties. The importance of male palms, locally named "Dokkars" on the quality and quantity of dates has been the subject of numerous works. In Tunisia, this genetic potential of the date palm, unrecognized wealth is now threatened, which makes it necessary to prospect and study this phylogenetic resource in order to protect it by the selection of better feet. Our present work, which is part of this framework, concerns the study of thirty samples of pollen harvested from the palm groves of the region of Djérid. In a first step, a characterization of the physiological parameters of the pollen was carried out, namely the germination test, viability, pH, conductivity and water content. In the second part, we worked only on ten pollinators. We tried to evaluate the effect of pollen conditioning temperature on the two main fertility parameters (germination and viability) by selecting two temperatures: room temperature and 4 ° C and this over a period of 8 months. The results obtained showed: the existence of variability in physiological characteristics from one individual to another, which reflects the great diversity of the Dokkars; The existence of a negative correlation between germination rate and pollen conductivity. Finally, the use of the refrigerator at 4 ° C, allows a better conservation of viability and germination of pollen.

Keywords: Dokkars, pollen, viability, germination, pH, water content, conductivity, refrigeration.

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Caractérisation physico-chimique et microbiologique des margines de différentes régions de la Tunisie (Nord, Sahel, Sud).

H. ZAIER *¹

 W. CHMINGUI²

H. RAJHI¹, D. BOUZIDI¹

S. ROUSSOS³

A. RHOUMA¹

¹ Laboratory of the improvement and protection of the genetic resources of the olive tree, Olive tree institute, Hédi Karray Street, P.O.Box 208, 2080, Ariana, Tunisia.

² Chemistry Laboratory for Water-Soil-Biosolids, National Research Institute for Rural Engineering, water, and Forestry, Hédi Karray Street, P.O.Box 10, 2080, Ariana, Tunisia.

³ Biotechnology and Chemometrics Team, St Jérôme Faculty, Campus Etoile, Aix Marseille University & Avignon University; IMBE UMR CNRS-7263/IRD-237, Case 421, 13397 Marseille cedex 20, France

Abstract – Olive mill wastewater (OMW) resulting from the extraction of olive oil is a major problem of the olive industry because of their highly polluting potential. The scientific research is increasing to propose alternatives solution to the direct discharge of these effluents into the natural environment. The objective of this work is to evaluate the degree of pollution OMW of the olive trituration units from different regions of Tunisia: north (Téboursouk, Al Karib, Gaâfour, Mornag), Sahel (Jemmal) and South (Sfax, Châal, Zarzis) by the determination of their physical-chemical and microbiological characteristics. The results of the physicochemical analyzes showed that the OMW of the different regions have an acidic pH and they are rich in organic matter, that is expressed by the BOD₅ and COD. These effluents are also characterized by the predominance of toxic substances, in particular phenolic compounds, the values are between 5.23 g/l in the Sfax region and up to 10.62 g/l in the Téboursouk region, which give them antimicrobial power. The report COD/BOD₅ is superior to 3 for all regions, which highlights the biodegradability of these OMW, where biological treatment appears to be quite appropriate. The count of the germs shows that the yeasts and the fungi represent the majority flora of the OMW of different regions. The analysis of the total aerobic mesophilic flora revealed that the largest number is recorded in the southern region (Sfax, Zarzis and Châal) compared to the other regions. This study showed also the total absence of fecal germs in the OMW of all the regions, which confirm that these effluents probably do not present a sanitary and hygienic problem and therefore is not considered an issue to the receiving environments.

Keywords : Olive mill wastewater, pollution, physical-chemical parameters, microbiology.

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W. ABIDI^1*

M.A. MORENO²

Y. GOGORCENA²

¹ Centre Régional des Recherches Agricoles (CRRA), Sidi Bouzid, Tunisie.

² Estación Experimental de Aula Dei (EEAD-CSIC), Zaragoza, España.

Abstract – The peach specie is one of the most spread stone fruit tree in the world. Nowadays, antioxidant compounds in human diet are becoming more and more important and it is of great interest to understand the genetic control of these fruit quality traits. This study was conducted in a F1 population (75 genotypes) derived from the cross ‘Venus’ x ’Big Top’ nectarines. The main objective of this work was to search for the phenotypic variability in the fruit quality traits and to study the QTLs involved in these fruit quality traits in peach. Agronomical traits such as tree yield (kg/tree), fruit weight (g) and the analysis of fruit quality parameters [firmness, soluble solids content (SSC), pH, titratable acidity (TA) and ripening index (RI)], were determined, in both the two progenitors and all the progeny. Biochemical analyses have been performed to measure vitamin C, total phenolics, flavonoids, anthocyanins and the relative antioxidant capacity. For QTLs detection, we began to construct a map mainly of the linkage group 6 (LG6) with polymorphic SSR markers. Linkage analysis has been performed using the JoinMap v 4.0 computer program and QTLs has been analysed with MapQTL v 6.0. To map the LG6, twenty three markers were assayed and only nine of them were polymorphic. QTLs involved in the control of biochemical traits and antioxidant capacity were not significantly localized in this linkage group. The addition of new polymorphic markers to this linkage group and others LGs is being implemented to complete the map in order to find significant QTLs affecting these fruit quality traits in nectarine.

Keywords : Nectarine, antioxidants, QTLs, SSR.

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