Y. Zarga*

H. Elfil

H. Ben Boubaker

LabTEN – Water Technologies Research Center, Technopole of Borj-Cedria, Tunisia

Abstract - This study focuses on calcium sulfate (gypsum) and calcium carbonate (CaCO₃) simple and mixed precipitations. These forms of scaling are still an issue in several industrial applications such as cooling towers and water desalination, either by thermal-based or membrane-based processes. CaCO₃ precipitation has been studied by the degassing method while the gypsum simple and mixed precipitations have been studied by the double decomposition method, and by following 4 parameters simultaneously, namely: pH and total alkalinity serve to detect the CaCO₃ precipitation, calcium ion concentration allows following the gypsum germination, and the quartz crystal microbalance (QCM) response gives information about the salts seeding, especially gypsum. A kinetic study of CaCO₃ and CaSO₄∙2H₂O mixed precipitation resulted in a different form to that of the simple precipitation. Indeed, even though the pH remains the key parameter to detect CaCO₃ precipitation either under simple or mixed precipitation forms, as the QCM response was found not to be a good parameter to detect the CaCO₃ germination in a mixed system, especially when it precipitates after calcium sulfate, the QCM response remains a specific parameter to gypsum crystals because even after the appearance of the first CaCO₃ crystals, gypsum germination continues with faster kinetics. Gypsum germination time in co-precipitation is higher than that corresponding to the simple precipitation (CaSO₄-H₂O system) because of the competition between the different co-precipitating ions.

Key words: Scaling / Simple and mixed precipitations / Germination / Degassing / Double decomposition.

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W. Mâaoui*

A. Ben Gara

B. Rekik

Laboratory of improvement and integrated development of animal productivity and food resources, Higher School of Agriculture of Mateur, University of Carthage, Tunisia

Abstract - Weights at 90 days were simulated for Barbarine lambs using various data and pedigree structures. The herd size, number of years and ram pedigree information were modified to cover probable structures of field data: Herds included between 100 and 2000 animals over 4 to 20 years with complete or missing ram information. Direct, maternal, permanent and residual variance components were estimated by Bayesian analysis via Gibbs sampling applied to an animal model that included the fixed effects of year and month of lambing, litter size, the age of the dam and sex of the lamb. A total of 30000 samples were generated. A burn-in period of 2000 rounds was used and then one out of 10 iterations was kept for subsequent analysis. Posterior means of direct and maternal variance effects ranged from 0,83 to 3,86 and from 2,30 to 4,34, respectively. Heritability estimates, in the same order, were between 0,06 and 0,29 and 0,16 and 0,28. In manner similar to direct estimates, maternal component estimates were closer to input parameters (3, 3,5, 9 and 7 for direct, maternal, permanent and residual variance, respectively) for increased herd sizes and number of years and complete ram pedigree.

Key words: Barbarine / growth / maternal effect / Sheep breed.

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H. AbdouLi ¹*

B. Omri ¹

L. Tayachi ¹

¹Laboratory of improvement and integrated development of animal productivity and food resources, Higher School of Agriculture of Mateur, University of Carthage, Tunisia

Abstract - Given the hypocholesterolemic property of fenugreek seed, the purpose of this study was to evaluate the effect of whole fenugreek seeds (WFS) and its water and hexane insoluble fraction (WHIFWFS) given to layers on laying performance and egg quality. Thirty, 69-week-old, Lohmann White laying hens (10 hens/treatment) were fed for 41 days 100 g/d of a basal diet (control), basal diet +1.75 g WHIFWFS and basal diet + 2 g WFS. Hen-day laying rate was not affected (P>0.05) by fenugreek addition. Mean weight of eggs laid throughout the whole experimental period was higher (P<0.05) for WHIFWFS (64.79 g) than for the control (62.23 g) and WFS (62.41 g). However, this difference was without consequence on mean egg mass and feed efficiency which were not affected (P> 0.05) by fenugreek addition. Physical characteristics of eggs laid on days 39-41, except shell weight which was the highest (P<0.05) for WHIFWFS, were not affected (P>0.05) by fenugreek addition. Fenugreek supplementation did not affect (P>0.05) triglyceride, total cholesterol and HDL cholesterol per g yolk and per egg. It was concluded that whole fenugreek seed given to Lohmann White laying hens had no effect on their laying performance and egg physical quality traits and cholesterol profile.

Key words: Fenugreek seed / egg cholesterol / laying hens

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