Metabolic fate of fatty acids involved in ruminal biohydrogenation in sheep fed concentrate or herbage with or without tannins1

Abstract

A 2 x 2 factorial experiment was carried out to evaluate the effect of herbage or concentrate feeding and dietary tannin supplementation on fatty acid metabolism and composition in sheep ruminal fluid, plasma, and intramuscular fat. Twenty-eight male lambs were divided into 2 equal groups at 45 d of age and kept in individual pens. One group was given exclusively fresh herbage (vetch), and the other group was fed a concentrate-based diet. Within each treatment, one-half of the lambs received supplementation of quebracho powder, providing 4.0% of dietary DM as tannins. Before slaughter, blood samples were collected. The animals were slaughtered at 105 d of age, and ruminal contents and LM were collected. Blood plasma, ruminal fluid, and LM fatty acid composition was determined by gas chromatography. Tannin supplementation reduced (P < 0.05) the concentration of stearic acid (-49%) and increased the concentration of vaccenic acid (+97%) in ruminal fluid from concentrate-fed lambs. Within concentrate- and herbage-based diets, tannin supplementation reduced the accumulation of SFA in blood (P < 0.05) compared with lambs fed the tannin-free diets. When tannins were included in the concentrate, the LM contained 2-fold greater concentrations of rumenic acid compared with the LM of the lambs fed the tannin-free concentrate (0.96 vs. 0.46% of total extracted fatty acids, respectively; P < 0.05). The concentration of PUFA was greater (P < 0.05) and SFA (P < 0.01) less in the LM from lambs fed the tannin-containing diets as compared with the animals receiving the tannin-free diets. These results confirm, in vivo, that tannins reduce ruminal biohydrogenation, as previously reported in vitro. This implies that tannin supplementation could be a useful strategy to increase the rumenic acid and PUFA content and to reduce the SFA in ruminant meats. However, the correct dietary concentration of tannins should be carefully chosen to avoid negative effects on DMI and animal performance.

The use of stoned olive cake and rolled linseed in the diet of intensively reared lambs: effect on the intramuscular fatty-acid composition

“…In fact, previous studies reported that some kinds of plant polyphenols might influence rumen microbe metabolism, affecting the biohydrogenation process of the dietary unsaturated fatty acids (Vasta et al, 2009;Buccioni et al, 2011;Jerónimo et al, 2012).…”

“…This pattern could be because of an additive effect of polyphenols and olive oil contained in the cake. Previous in vitro and in vivo studies, in fact, demonstrated a significant effect of dietary polyphenols on the rumen bacterial community, which resulted in a decrease of BCFA content in both rumen liquor and intramuscular fat (Vasta et al, 2009;Buccioni et al, 2011).…”

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

“…Hence, when the present study was planned, two different sources of tannins were selected: chestnut as a source of HT and quebracho as a source of CT. These sources were chosen because widely used in the Mediterranean area as additive in small ruminant diets (Vasta et al, 2009). The percentages and the type of tannins used in this trial did not alter the pH value of rumen liquor, buffered with McDougall solution (McDougall, 1948).…”

“…The extent of tannin effects may vary according to differences in -E-mail: arianna.buccioni@unifi.it the structure and molecular weights of both tannins and dietary proteins (Min et al, 2003). Vasta et al (2008Vasta et al ( , 2009Vasta et al ( , 2010 suggested that ruminal biohydrogenation (BH) is affected by CT and that tannins could be a potential means to increase rumenic (RA; C18:2 cis9, trans11) and vaccenic acid (VA; C18:1 trans11) content in food of animal origin. Studies in animal models and in vitro demonstrate that RA has potential anticarcinogenic properties (Benjamin and Spener, 2009).…”

Browsing ratio, species intake, and milk fatty acid composition of goats foraging on alpine open grassland and grazable forestland

“…Particularly, iso-BCFA are synthesized by cellulolytic strains (the microorganisms mainly involved in ruminal BH; Kepler and Tove, 1967), consequently being considered valuable predictors of ruminal bacterial activity. Tanniferous compounds were reported to reduce considerably the concentration of iso-BCFA in the rumen (Vasta et al, 2009a(Vasta et al, , 2009b(Vasta et al, , 2010.…”