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Theses

The metabolism of terprenoides in caprins

Malecky Mostafa
Abstract : The main objective of this thesis is to study in vitro and in vivo the metabolism of some terpenes characteristic of winter-spring ration ingested by dairy goats in the region of Basilicata (Italy). We sought to quantify as the first step, the metabolism of terpenes in the fermentation broth in vitro and to characterize the major variation factors of their metabolism. We also conducted a test in vivo on 4 individual terpenes (-pinene, -pinene, p-cymène and linalool, the main terpenes ingested by goats in Basilicata), in order to validate the results obtained in vitro, to characterize their changes in the rumen, and their duodenal and blood flow level. In parallel we have studied the impact of these terpenes on ruminal metabolism of cell walls and protein, as well as their effects on the performance of dairy goats. The experimental part is composed of three sets of studies. The methodological studies, in vitro and in vivo studies of metabolism of terpenes. The methodological optimization studies of an extraction and analysis method (SPME "Solid Phase Microextraction") have been conducted in order to obtain the optimum conditions for the extraction of terpenes in the fermentation broth and blood matrix. The first in vitro essay led to a discrimination of tested terpene in terms of their disappearance in the rumen juice, which has been associated to chemical type of considered terpene. The hydrocarbons terpenes showed indeed a much greater disappearance compared to oxygenated ones. This difference is mainly due to differences in their physico-chemical properties, which separates in part their metabolic pathway. The disappearance of terpenes appears to have two main causes, biological intervention of microbial origin and interaction with the matrix. A lower toxic and higher hydrophobic property seems to reinforce the microbial metabolism and the intervention of the matrix on hydrocarbon terpenes compared to those oxygenated ones. In the second test in vitro, the effect of three variables, the type of inoculum (rich in cell walls vs. rich in starch), the type of bacteria (gramme positive vs gramme negative- selected by the contribution of antibiotic) and the redox potential were studied on the metabolism of terpenes in the fermentation broth. The results showed that the inoculum high in cell walls, theoretically supporting cellulolytic bacteria increases the apparent degradation of terpenes. The absence of an effect from the addition of the antibiotic eliminating gramme positive bacteria showed that the gramme negative bacteria are principal responsible, which contribute to the metabolism of terpenes. Finally, the increase in the redox potential increased the disappearance of some of tested terpenes, especially in the inoculum rich in starch. The results from in vitro studies on the metabolism of terpenes, were confirmed by those observed in vivo. However a higher disappearance observed in vivo suggested the involvement of other varying factors that can be attributed to the absorption in the rumen and a loss from rumination and belching. The impact of terpenes on rumen metabolism and performance of dairy goats was studied by incorporating a mixture of four terpenes (mentioned above) at two doses (0.05 and 0.5 ml / kg DMI). Ingestion of terpenes did not produce any effect on the ruminal metabolism of cell walls, and protein. The productivity performance goats were not affected by terpenes, but a change in the milk protein content (a drop in protein content at low dose) observed, can be considered as a secondary effect (effect of dilution) linked to a numerically increase in the milk production at this dose level.
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Theses
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https://pastel.archives-ouvertes.fr/pastel-00004406
Contributor : Ecole Agroparistech <>
Submitted on : Wednesday, December 3, 2008 - 8:00:00 AM
Last modification on : Wednesday, December 3, 2008 - 8:00:00 AM
Long-term archiving on: : Thursday, September 30, 2010 - 8:36:19 PM

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Malecky Mostafa. The metabolism of terprenoides in caprins. Life Sciences [q-bio]. AgroParisTech, 2008. English. ⟨NNT : 2008AGPT0032⟩. ⟨pastel-00004406⟩

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