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The effect of the essential oils of thyme on the in vitro ruminal degradability of a barley seed/alfalfa hay substrate was studied. Two essential oils were used, one from Thymus hyemalis (TH), rich in carvacrol, and the other from Thymus zygis (TZ), rich in thymol. Four experimental treatments of in vitro degradability, using the Daisy II(200/220) incubator, were conducted including a negative control (CO), a positive control at 7.5 microg/mL of monensin (MO), and two treatments with essential oils (TH or TZ) at 1.35 microL/mL. The material was incubated at 39.5 degrees C for various lengths of time. At each time, the disappearance of dry matter, crude protein, and neutral detergent fiber was measured. Volatile fatty acids (VFAs) were determined after 48 h of incubation. CO and MO provided (p < 0.01) higher values of potential degradability (a + b) of DM than the TH and TZ treatments (72.6 and 70.8 vs 53.2 and 48.2%, respectively). Also, crude protein degradability was lowest in the essential oil treatments. The CO treatment showed the highest potential degradability of NDF. The values of VFA production obtained (p < 0.001) with CO and MO treatments were higher than those obtained with TH and TZ treatments (21.0 and 19.1 vs 11.2 and 10.1 mM). The essential oils decreased the molar proportion of propionate, increasing the acetate/propionate ratio. In conclusion, the effects of essential oils at assayed doses would not be nutritionally beneficial to the ruminal energetic metabolism.

The objective of this study is to identify the principal fatty acids in Murciano-Granadina goats' milk. The technique used to identify and quantify the se acids was gas chromatography through flame ionization and mass spectrometry. The principal fatty acids found were butyric acid (3.0%), caproic acid (6.3%), caprylic acid (2.5%), capric acid (10.4%), laurie acid (5.6%), myristic acid (12.8%), palmitic acid (34.8%), stearicacid (6.8%), oleic acid (13.3%), linoleic acid (3.6%) and linolenic acid (0.9%). Using the results obtained, a descriptive statistical study was undertaken. The relationship between fatty acids was determined using Pearson's correlation matrix, and highly significant negative statistical correlations were found between palmitic acid and the other fatty acids studied, although no significant correlations were found between the quantity of fat present in the milk and the values of fatty acids. © Inra/Elsevier, Paris. goat milk / fat / fatty acid / gas chromatography Résumé-Les acides gras dans le lait de chèvre murciano-granadina. L'objectif de ce travail est la quantification des acides gras majeurs dans le lait de chèvre murciano-granadina. La technique d'identification de ceux-ci a été la chromatographie en phase gazeuse avec ionisation de flamme et la spectrométrie de masse. Les acides gras majeurs déterminés sont les acides butyrique (3,0 %), caproïque (6,3 %), caprylique (2,5 %), caprique (10,4 %), laurique (5,6 %), myristique (12,8 %), palmitique (34,8 %), stéarique (6,8 %), oléique (13,3 %), linoléique (3,6 %) et linolénique (0,9 %). Les acides palmitique (34,8 %), myristique (12,8 %) et oléique (13,3 %) présentent les pourcentages les plus élevés. À partir des résultats obtenus, une étude statistique descriptive a été réalisée. Les relations des acides gras entre eux et avec le pourcentage de matière grasse dans les échantillons ont été déterminées à travers la matrice de corrélation de Pearson. Des corrélations négatives significatives ont été trouvées entre l'acide palmitique et les autres acides gras étudiés, mais il n'y a pas de corrélations significatives entre la quantité de matière grasse du lait et les proportions individuelles des acides gras. © InralElsevier, Paris.