Effect of three species of herbage (Medicago sativa, Lolium multiflorum, Avena sativa) onin vitroruminal production of conjugated linoleic and vaccenic acids

Abstract

Little information is available about the effect of different forage species on the rumen biohydrogenation process. The aim of the present work is to compare the in vitro production of cLA and c18:1 isomers after incubation of three different herbage species in rumen liquor from sheep. Pasture herbage samples of lucerne (Medicago sativa; MS), ryegrass (Lolium multiflorum; LM) and oats (Avena sativa; AS) were submitted to in vitro fermentation with sheep rumen inoculum. Samples were collected at 2, 4, 6 and 8 hours of fermentation.The fatty acid profile of MS was characterised by 11.62 (g/100 g of lipid extract) of linoleic acid (LA) and 27.08 (g/100 g of lipid extract) of α-linolenic acid (LNA), whereas LA in the other two herbages was 6.60 (g/100 g of lipid extract) and 6.95 (g/100 g of lipid extract) in AS and LM, respectively; LNA was 52.20 (g/100 g of lipid extract) and 54.49 (g/100 g of lipid extract) in AS and LM, respectively. The crude fat content of botanical species was respectively 11.90 (g/100g DM) for AS, and 15.77 (g/100g DM) for LM and 26.17 (g/100g DM) for MS. Rumenic acid (RA, cis-9, trans-11 CLA) was the predominant CLA isomer and the maximum yield was attained with AS after 6 hours of fermentation (0.81 g/100 g of lipid extract); RA concentration remained quite low with the other two herbages. The concentration of the other isomer (trans-10, cis-12 CLA) was always very low; the maximum yield (0.09 g/100 g of lipid extract) was reached after 6 hours with AS. The maximum yield of vaccenic acid (VA, trans-11 C18:1) was reached after 8 hours with MS (2.64 g/100 g of lipid extract). This herbage also produced the highest amount of trans-10 C18:1 at 6 and 8 hours (0.17 g/100 g of lipid extract). AS appeared to have induced the highest amounts of RA relative to the other two forages. The differences in conjugated dienes and c18:1 isomers content during fermentation could be due not only to different amounts of LA or LNA in the herbage, but also to different releasing times of FA from the plant substrate.

Lipid metabolism in the rumen: New insights on lipolysis and biohydrogenation with an emphasis on the role of endogenous plant factors

“…The literature agrees in showing that minor isomers reach their maximum concentration in rumen liquor later than main isomers (Buccioni et al, 2006(Buccioni et al, , 2008(Buccioni et al, , 2009Wallace et al, 2007).…”

Meat Quality of Lambs Fed Different Saltbush Hay (Atriplex Nummularia) Levels

“…Some studies reported a greater proportion of linolenic acid and its derivatives in the fat of grazing sheep than those fed concentrate diets, consistent with the results of this work (Woods and Fearon, 2009;Oliveira et al, 2013). Although the most studies usually find higher biohydrogenation in forage fed animals than in concentrate fed animals, another authors reports lower biohydrogenation in the rumen when the diet is composed of a higher level of forage (Antongiovanni et al, 2003;Abidi et al, 2009;Buccioni et al, 2009).…”

Effect of chestnut and quebracho tannins on fatty acid profile in rumen liquid- and solid-associated bacteria: an in vitro study

“…The incubator consisted of a thermostatic chamber (398C) equipped with forty-five 300 ml glass fermentation vessels provided with two inlets (one to release gas through a valve and one for the pH probe). Each vessel contained substrate inoculated with rumen fluid, as described above, according to Buccioni et al (2009). Incubation times were 6, 12 and 18 h. After all incubation periods, three vessels per treatment were used for rumen content fractionation and subsequent FA analysis, as described below.…”