Abstract:
The secondary metabolites of aromatic and medicinal plants have received a lot of attention in recent years due to their ability to biological activities. These compounds would be of dual interest for the health of ruminants and for the nutritional value of their products (milk and meat). About that and within the framework of the valorization of the endemic plants, the objectives of this thesis are: (i) to inventory the aromatic and medicinal plants grazed by the goats and to list their effects on the quality of milk by means of a survey carried out among farmers in the Aurès Mountain area; (ii) analyze the profiles of terpene and phenolic compounds of these aromatic and medicinal plants; (iii) and study the phenolic compounds and their metabolites in goat milk supplemented with Artemisia herba alba. A survey was carried out among 70 farmers in the Aurès Mountains (Batna). Colorimetric tests were used for the analysis of phenolic extracts from the selected plants and chromatographic tests (HPSPME-GC-MS and HPLC-DAD) were used for the analysis of terpene compounds and phenolic compounds from the selected plants, respectively. Antiradical activity and antioxidant activity were assessed by the DPPH• test and the β-carotene bleach test, respectively. The aromatic and medicinal plants most consumed by goats (with the high citation frequency) are: Thymus algeriensis> Artemisia herba alba Asso> Rosmarinus officinalis L.> Juniperus phoenica L.> Artemisia campestris L> Marrubium vulgare L. Thymus algeriensis and Artemisia herba alba Asso are both the most abundant plants in the Aures Mountains and the most grazed by goats. The main volatile compounds identified by HP-SPME-GC-MS are α-pinene (40%), β-thujone (38%), trans-caryophyllene (31%), β- myrcene (29%), camphor (27%), and α-thujone (18%). The phyto-chemical screening by HPLC-DAD of aromatic and medicinal plants shows their richness in phenolic compounds. The most abundant classes of phenolic compounds detected are flavonoids (3-51 mg.g-1 DM), derivatives of cinnamic acid (0.5-36 mg.g-1 DM), derivatives of benzoic acid (0.1-5.5 mg.g-1 DM) and coumarins (0.1-2.4 mg.g-1 DM). The contents of t-o-coumaric acid and 3-hydroxycinnamic acid (unidentified) in the milk of goats experimenting following a diet with Artemisia herba alba were higher than those of control goats with a significant difference (p <0.001). The present work indicates that the aromatic and medicinal plants that grow in the Aurès Mountains of Algerian are rich in phenolic compounds and could be offered as food
for goats to improve the quality goat milk.
