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This Article Full Text (PDF) All Versions of this Article: jas.2008-1761v1 87/8/2674    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Vasta, V. Articles by Priolo, A. Search for Related Content PubMed PubMed Citation Articles by Vasta, V. Articles by Priolo, A.

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

V. Vasta^*, M. Mele, A. Serra, M. Scerra^*, G. Luciano^*, M. Lanza^* and A. Priolo^*

^* DACPA - University of Catania, Via Valdisavoia 5, 95123, Catania, Italy University of Pisa, Italy Dipartimento di Agronomia e Gestione dell’Agro-Ecosistema, via del Borghetto 80, 56124 Pisa, Italy

vvasta{at}unict.it

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, half of the lambs received supplementation of quebracho powder, providing 4.0% of dietary DM as tannins. Before slaughtering, 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 both concentrate- and herbage-based diets, tannin supplementation reduced the accumulation of SFA in blood (P < 0.05) compared to the lambs fed the tannin-free diets. When tannins were included in the concentrate, the LM contained 2-fold higher levels of rumenic acid as compared to 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 to 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.

Key Words: CLA • Fatty acids • Feeding system • Sheep • Tannins