Evaluation of the antioxidant and antibacterial activities of Tunisian Artemisia Herba-alba essential oil

Tunisia is characterized by a climate that allows the proliferation of many plants rich in active substances with multiple biological activities and can replace the use of antioxidants and synthetic antibiotics. For this reason, Artemisia leaves and twigs were collected from the central region of Tunisia (Thala). The essential oil was extracted using hydro-distillation and analyzed using GC/MS, the antioxidant activity of Artemisia Herba-alba was evaluated by the DPPH test and the antibacterial powers against four bacterial strains was measured by the agar well method diffusion. GC/MS results showed that the main components of Artemisia Herba-alba essential oil were ?-thujone (23.9 %) and chrysanthenone (17.4%). Indeed, the results showed a potent antioxidant effect (85.2 % inhibition of free radicals DPPH) and the IC50 value was 84.8 µg/ml. Concerning the antibacterial activity, the oil was active against Gram-negative and Gram-positive bacteria. A strong effect was observed against Salmonella (29mm) and Bacillus (22.5 mm). To conclude, the antioxidant power and the antibacterial activity are strongly correlated with the chemical composition of the essential oil. Keywords: Artemisia Herba-alba, essential oil, antioxidant activity, antibacterial activit

Meat quality of Tunisian local breed lambs supplemented with olive pomace blocks

Animal feed cost in Tunisia is extremely high and the search for alternative solutions is imperative. In this study, we tested the supplementation of weaned lambs with olive pomace-based blocks to evaluate their effect on meat quality and profitability of lamb fattening. For this purpose, we divided sixteen weaned male lambs of the "Noir de Thibar" breed into two distinct groups of 8 lambs each. The experiment was conducted over a period of 3 months. Each group received 700 g of oat hay/lamb/day and a specific feed supplement: Control group (group C) received 500 g of commercial feed concentrate/lamb/day during the 3 months of the fattening experiment. The set of lambs supplemented with feed blocks (set B) received 200 g of feed blocks containing 32% olive meal and 300 g of feed concentrate/lamb/day. The carcass yield of the control lambs (C) was higher than that of the lambs in the other group. The lambs' consumption of feed blocks resulted in a decrease in the redness and yellowing of the meat they produced. Supplementation with feed blocks as well as feed restriction reduced the concentration of lauric and myristic acids (saturated fatty acids) in the intramuscular fat of the lambs compared to the control group, and lambs fed with feed blocks based on oilcake produced meat with high percentage of oleic acid (monounsaturated fatty acid) compared to lambs consuming contaminated feed concentrates. Keywords: Olive cake, feed blocks, Carcass characteristics, Meat quality, Intramuscular fatty acid

Milk production of imported heifers and Tunisian-born Holstein cows

peer reviewedTest day (TD) records of milk, fat and protein yields and somatic cell scores (SCS) were studied in Holstein cows in Tunisia. There were 43114, 32923 and 24633 lactation records collected on first, second and third parity cows between 1992 and 2004 in 182 herds. Records were of cows born in Tunisia (22000 cows) and those imported from Europe (10830 cows) and North America (850 cows). Variation of total days in milk (DIM) per lactation was studied in function of the herd, calving year x calving season interaction and the origin of the cow. Test-day records were analyzed using a linear model that included calving year x calving season and herd x test-day date interactions, calving season, calving year and origin of the cow. The effective length of lactation was affected by all factors included in the model (p0.05). Cows born in Tunisia seemed to perform better than imported cows in the first lactation while imported cows showed clearly better performances in later lactations. North American cows produced the highest yields and had the lowest SCS among all cows in the second and third lactations. Imported high producing cows seemed able to adjust to Tunisian management conditions following their first lactation

Mid infrared and fluorescence spectroscopies coupled with factorial discriminant analysis technique to identify sheep milk from different feeding systems

peer reviewedMid infrared spectroscopy (MIR) combined with multivariate data analysis was used to discriminate between ewes milk samples according to their feeding systems (controls, ewes fed scotch bean and ewes fed soybean). The MIR spectra were scanned throughout the first 11 weeks of the lactation stage. When factorial discriminant analysis (FDA) with leave one-out cross-validation was applied, separately, to the three spectral regions in the MIR (i.e. 3000-2800, 1700-1500 and 1500-900 cm(-1)), the classification rate was not satisfactory. Therefore, the first principal component (PCs) scores (corresponding to 3, 10 and 10 for, respectively, the 3000-2800, 1700-1500 and 1500-900 cm(-1)) of the principal component analysis (PCA) extracted from each of the data sets were pooled (concatenated) into a single matrix and analysed by FDA. Correct classification amounting to 71.7% was obtained. Finally, the same procedure was applied to the MIR and fluorescence data sets and 98% of milk samples were found to be correctly classified. Milk samples belonging to control and soybean groups were 100% correctly classified. Regarding milk samples originating from the scotch bean group, only 2 out of 33 samples were misclassified. It was concluded that concatenation of the data sets collected from the two spectroscopic techniques is an efficient tool for authenticating milk samples according to their feeding systems, regardless of the lactation stage. (C) 2011 Published by Elsevier Ltd

Caractérisation nutritionnelle des blocs multi-nutritionnels à base de grignons d’olives

Olive cake-feed blocks were manually made to assess their nutritional properties. They were prepared using: olive cake (32%), processed barley (25%), wheat bran (15%), soybean meal (10%), salt (5%), vitamin and mineral premix (3%), and quicklime (10%). No secondary metabolites were detected in our handmade feed blocks nor any antioxydative activity. Organic matter digestibility is low (49.2%) albeit the level of metabolizable energy is considerable (7 MJ/kg DM). Gas production kinetics were measured in vitro for 48 h in order to simulate ruminal gas production following feed block consumption. Olive cake-feed blocks may substitute expensive concentrates and reduce methane emission by ruminants. Keywords: Olive cake-feed blocks, Chemical composition, Gas production.Des blocs multi-nutritionnels à base de grignons d’olives étaient fabriqués manuellement en vue d’étudier leurs caractéristiques nutritionnelles. Ces blocs sont composés de : grignons d’olives (32%), orge broyé (25%), son de blé (15%), tourteaux de soja (10%), sel alimentaire (5%), un complément de minéraux et de vitamines (3%), et enfin de la chaux vive (10%) comme fixateur. L’analyse de la composition chimique des blocs alimentaires fabriqués a révélé qu’ils sont dépourvus de métabolites secondaires et par conséquent ne possèdent nullement d’action antioxydante. La digestibilité de la matière organique est médiocre (49,2%) mais le taux de l’énergie métabolisable est bien élevé (7 MJ/kg MS). Enfin, la cinétique de la production des gaz émis suite à la consommation des blocs par les ovins était simulée in vitro durant 48 h puis modélisée. Les blocs multi-nutritionnels formulés à base de grignons d’olives pourraient probablement réduire l’émission de méthane (gaz à effet de serre) par les ruminants et pourraient remplacer des aliments plus coûteux dans l’alimentation des petits ruminants. Mots-clés : Blocs multi-nutritionnels, Grignons d’olives, Composition chimique, Production des gaz

Optimal age at first calving for improved milk yield and lengh of productive life in Tunisian Holstein cows

peer reviewedThe effects of age at first calving on milk production and true herd life were studied in Tunisian Holstein cows. There were 33,407 first lactation records of cows born between 1987 and 2001 from 166 herds. Firstly, age at first calving was analyzed using an animal model that included herd, calving year, herd-calving year interaction, calving month, and age of dam as fixed effects and the random additive genetic effect. Secondly, differences in first lactation and productive life milk yields and in true herd life were explained by age at first calving in addition to herd, year at first calving, herd-year at first calving interaction and month at first calving. A cow produced on the average 5669.8 kg milk (SD=1812 kg) during a 305-d first lactation period. The lifetime production of a cow was was 19,496.3 kg (SD=12,192 kg) during 3.3 lactations (SD=1.8 lactations). Coefficients of determination ranged from 14% for true herd life to 64% for first lactation milk yield. The mean of true herd life was 38.6 months (SD=24 months) and the mean age at first calving was 28.7 months (SD=3.4 months). Posterior mean of heritability of the age at first calving derived by a Markov Chain Monte Carlo Bayesien method via a Gibbs sampling algorithm was 0.08. The reduction of age at first calving to around 24 months may result in improved 305-d and lifetime yields and a longer herd life in Tunisian Holsteins

Production laitière sous les conditions méditerrannènnes: Cas de la Tunisie

peer reviewe

Use of Front-Face Fluorescence Spectroscopy to Differentiate Sheep Milks from Different Genotypes and Feeding Systems

The objective of the present study was to assess the potential of front-face fluorescence spectroscopy coupled with chemometric tools for the evaluation of the quality of milk samples according to the feeding system and genotype. Fifty (n = 50) ewe's milk samples were scanned after excitation set at 250, 290, 322, and 380 nm and emission set at 410 nm. Thirty out of the 50 samples composed the first trial and were obtained from two different genotypes (i.e., Comisana versus Sicilo-Sarde); the second trial was composed of 20 samples obtained from the Sicilo-Sarde genotype with two different feeding systems in pen (soybean versus scotch bean). Milk samples were divided into four groups named Sicilo-Sarde with pasture feeding (Spas), Comisana with pasture feeding (Cpas), Sicilo-Sarde feeding on scotch bean (Ssco), and Sicilo-Sarde feeding on soybean (Ssoy). The factorial discriminant analysis was applied to the: (i) four groups (i.e., Spas, Ssco, Ssoy, and Cpas) and (ii) three groups composed only of Sicilo-Sarde genotype (i.e., Spas, Ssco, and Ssoy). Considering the four groups, the best result was obtained with the excitation vitamin A spectra since correct classification amounting to 76% was observed. When the factorial discriminant analysis was performed with the three groups belonging to the Sicilo-Sarde genotype, the best result was obtained again with vitamin A spectra (i.e., emission and excitation spectra) since 88.6% of correct classification was observed. Concatenation technique applied to the five fluorescence spectra improved the rate of classification between the four groups since 44 out of 50 samples were correctly classified. No misclassification was observed between milk samples collected from ewes with pasture feeding from the pen feeding. It was concluded from the obtained results that fluorescence spectroscopy could be considered as a powerful tool for differentiating between raw milks according to both genotype and feeding system