期刊
BRITISH JOURNAL OF NUTRITION
卷 108, 期 12, 页码 2207-2214出版社
CAMBRIDGE UNIV PRESS
DOI: 10.1017/S0007114512000335
关键词
Protozoa; Chloroplasts; Fatty acids; Denaturing gradient gel electrophoresis; Quantitative PCR; Biohydrogenation; Rumen
资金
- Biotechnology and Biological Sciences Research Council (UK)
- Department of Environment Food and Rural Affairs
- English Beef and Lamb Executive
- Hybu Cig Cymru
- Quality Meat Scotland
- European Union Prosafebeef [FOOD-CT-2006-36241]
- BBSRC [BBS/E/W/10964A01B, BBS/E/W/10964A01A, BBS/E/W/10964A01C] Funding Source: UKRI
- Biotechnology and Biological Sciences Research Council [BBS/B/11818, BBS/E/W/10964A01C, BBS/E/W/10964A01B, BBS/E/W/10964A01A] Funding Source: researchfish
Ruminant products are criticised for their SFA content relative to PUFA, although n-6:n-3 PUFA is desirable for human health (<4). Rumen protozoa are rich in unsaturated fatty acids due to engulfment of PUFA-rich chloroplasts. Increasing the chloroplast content of rumen protozoa offers a potentially novel approach to enhance PUFA flow to the duodenum and subsequent incorporation into meat and milk. We evaluated protozoal contribution to duodenal n-3 PUFA flow due to intracellular chloroplast content. A total of six Holstein x Friesian steers were fed, in a two-period changeover design, either straw:concentrate (S:C, 60:40; DM basis; S:C, low chloroplast) or fresh perennial ryegrass (PRG; high chloroplast). Following 12 d adaptation to diet, ruminal protozoal and whole duodenal samples were obtained. N and fatty acid content of whole duodenum and rumen protozoal samples were assessed and protozoal 18S rDNA quantitative PCR performed, enabling calculation of protozoal N flow. The ratio of individual fatty acids:N in rumen protozoal samples was calculated to obtain protozoal fatty acid flows. Based on total fatty acid flow, contribution (%) of protozoa to individual fatty acid flows was calculated. Protozoal fatty acid data and microscopical observations revealed that protozoa were enriched with 18:3n-3 following PRG feeding, compared with the S:C diet, due to increased intracellular chloroplast content. However, duodenal protozoal 18S rDNA concentration post PRG feeding was low, indicating rumen retention of the protozoa. Nutrition influences the 18:3n-3 content of protozoa; the challenge is to increase protozoal flow to the small intestine, while maintaining sustainable rumen densities.
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