title: Rumen protozoa are rich in polyunsaturated fatty acids due to the ingestion of chloroplasts.
abstract: Within this study, we investigated whether the polyunsaturated fatty acids (PUFA)-rich nature of rumen protozoa is a consequence of ingestion of PUFA-rich chloroplasts. Four Hereford x Friesian steers were offered hay [low 18:3 (n-3) and low chlorophyll concentration] followed by freshly cut perennial ryegrass [high 18:3 (n-3) and high chlorophyll concentration] for 16 days. On the 14th and 16th days, rumen protozoa as well as attached and planktonic bacteria were fractionated 1 h before (-1 h), 2 and 6 h postfeeding, and their fatty acid concentrations determined. Protozoa fractionated from fresh grass-fed steers were richer (P<0.05) in PUFA, except conjugated linoleic acid, for all time points compared with those from hay-fed steers. Protozoal density was higher (P<0.05) for grass compared with hay. Entodinomorphid abundance was 3.4 times higher on fresh grass (P<0.01) compared with hay. Confocal microscopy and transmission electron microscopy confirmed that Epidinium spp. were commonly saturated with intracellular cytoplasmic chloroplasts. These data suggest that engulfment of chloroplasts is a major contributor to the high 18:3 (n-3) concentration of protozoa.
authors: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth SY23 3EB, UK.
authors: Sharon A
authors: SA
authors: Huws
authors: Eun J
authors: EJ
authors: Kim
authors: Alison H
authors: AH
authors: Kingston-Smith
authors: Michael R F
authors: MR
authors: Lee
authors: Stefan M
authors: SM
authors: Muetzel
authors: Alan R
authors: AR
authors: Cookson
authors: Charles J
authors: CJ
authors: Newbold
authors: R John
authors: RJ
authors: Wallace
authors: Nigel D
authors: ND
authors: Scollan
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D056890:Eukaryota / Q000235:genetics / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D008297:Male; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012417:Rumen / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; D016054:DNA, Protozoan; D005231:Fatty Acids, Unsaturated; D012336:RNA, Ribosomal, 16S; D012337:RNA, Ribosomal, 18S; D002734:Chlorophyll