Etude de la valeur nutritive de légumineuses arbustives du genre Acacia.

Abstract

"This thesis is focused on the study of the effect of condensed tannin-rich fodder, Acacias collected from several regions of Algeria, on sheep ruminal microbiota. Foliage chemical composition of nine plants, including five Acacias ( A.nilotica , A.horrida , A.albida , A.julibrissin , A.cyanophylla , A.halimus , Vicia faba , A. herba alba and P.granatum ) are performed according to standard methods. The results of these analysis showed significant differences ( p < 0,05 ) between these species . Shrub legumes have the advantage of being rich in PB with values ranging from 156,6 to 252,0 (g / kg DM) , and the disadvantage for some , to be rich in ADL ( anti-nutritional factor ) with values recorded in A.nilotica , A.albida and A.cyanophylla; 126 , 139.7 and 147,5 ( g / kg DM) , respectively. Acacias have the highest rate in polyphenols, mainly tannins condensed. Our results are similar to those reported by several authors. The study of the biological activity of these tannins , using PEG coupled to the gas production technique , shows that only condensed tannins of A.cyanophylla and A.nilotica are significantly active ( p < 0,05 ) . This confirms the results of other studies showing the antagonistic effects of TC. The digestibility was performed using two methods, in vivo (in Sacco) and in vitro (according to Tilley and Terry), is tested by providing acceptable levels for these plants. A. Albida, despite its low TC, and ADL shows relatively low levels of digestibility. The effect of these substrates on the ruminal microbiota of two different breeds, Merino Shurra and gives significantly different results (p < 0,05) with A.cyanophylla and A.nilotica, only. The side impact des Acacias studied compounds in reducing methane production is tangible. The analysis of the amount of methane produced in the presence and absence of PEG, showed significant differences (p < 0.05) for all used Acacias. Condensed Tannins contained in these Fabaceae have a negative effect on ruminal methanogenesis. Which recommend the use of Acacias to reduce nitrogen losses and in turn curb the harmful effects on the environment of CH4 belching."