Rumen protozoa are rich in polyunsaturated fatty acids due to the ingestion of chloroplasts |
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Authors: | Sharon A Huws Eun J Kim Alison H Kingston-Smith Michael RF Lee Stefan M Muetzel Alan R Cookson Charles J Newbold R John Wallace & Nigel D Scollan |
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Institution: | Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth, UK;;and Rowett Research Institute, Bucksburn, Aberdeen, UK |
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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 × 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. |
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Keywords: | rumen protozoa planktonic and attached bacteria fatty acid chloroplast DGGE QPCR |
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