Ellis, N.

Kim, E. J.

Lee, Michael R. F.

Scollan, Nigel D.

Tweed, J. K. S.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XXI International Grassland Congress / VIII International Rangeland Congress Milk C18 Polyunsaturated Fatty Acids from Cows Grazed on Perennial Ryegrass, Tall Fescue or Timothy Grass Swards Michael R. F. Lee Institute of Grassland and Environmental Research, UK E. J. Kim Institute of Grassland and Environmental Research, UK N. Ellis Institute of Grassland and Environmental Research, UK J. K. S. Tweed Institute of Grassland and Environmental Research, UK N. D. Scollan Institute of Grassland and Environmental Research, UK Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/15-1/11 The XXI International Grassland Congress / VIII International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 瞯 658　 瞯 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅱ 　Grasslands/Rangelands Production Systems ——— Forage Quality ,Conservation and UtilizationMilk C18 polyunsaturated fatty acids from cows grazed on perennial ryegrass , tall fescue ortimothy grass swardsM .R .F . Lee , E . J . K im , N . Ellis , J .K .S Tweed and N .D . ScollanInstitute o f Grassland and Environmental Research , Plas Gogerddan , Aberystwyth , Ceredigion , UK , SY23 3EB michael .lee ＠ bbsrc .ac .ukKey words : C１８ polyunsaturated fatty acids ,perennial ryegrass ,tall fescue ,timothy ,milk fatIntroduction Previous work at our institute has shown substantial variation in the degree of cell damage during ingestion andmastication of different grasses , resulting in differences in the release rate of nitrogen and lipid into rumen fluid ( Kim et al .２００８ ) . These differences in the release rate of lipid may influence the extent of biohydrogenation in the rumen and consequentlythe C１８ polyunsaturated fatty acid ( PUFA) content of ruminant products . This study investigated the C１８ PUFA of milk fromcows grazing three contrasting grass species ( perennial ryegrass , PRG ; tall fescue , TF ; and timothy , TIM) over two years .Materials and methods Three grass genotypes : PRG , TF and TIM were sown in plots (０ .７ ha) in August ２００４ . In April ２００５and May ２００６ , １２ multi‐parous Holstein × Friesian dairy cows in mid‐lactation were allocated to treatment at random in areplicate ３ × ３ Latin square design . Each period consisted of ２ weeks grazing followed by a ３ week rest period where all cowsgrazed together on permanent pasture . Herbage intake was calculated at the end of each grazing period using the differentialgrowth method as assessed by exclosure cages ( Lee et al .２００１ ) . Cows at milking received ２ kg/ day of standard １８ ％ proteindairy concentrate . Milk yield was recorded across the experiment . Milk from the last two days of each period was sub‐sampledand submitted for fatty acid analysis . Fatty acids were extracted and methylated using a single step base ( NaOH in methanol)catalysed methylation . Statistical analysis was carried out using a general ANOVA with grass species × year as the treatmentand blocking according to cow ＋ period ( Payne et al . ２００２ ) .Results and discussion DM and C１８ PUFA intake was significantly lower for TF than the other two grasses and similar acrossyears with the exception of TIM which was lower in ２００６ ( Table １ ) . Milk yields were also lower on TF than the other grassesand higher in ２００５ than ２００６ . Milk PUFA output was highest in ２００６ for all grasses . C１８ :２ in milk showed the pattern TIM＞ PRG ＞ TF , whereas for C１８ :３ PRG ＞ TF ＞ TIM and is likely to be associated with a substrate input effect . Conversionefficiency of C１８ :２ was significantly higher for TF than the other grasses , it also showed the fastest release rate of lipid in arumen environment ( Kim et al . ２００８ ) . This may facilitate its passage through the rumen and reduce biohydrogenation .However , as to why this response was not seen for C１８ :３ requires further investigation .Table 1 C１８ PUFA intake , milk output and percentage conversion e f f iciency f or the three grasses over two years .Perennial Ryegrass Tall fescue Timothy P２００５ ２００６ ２００５ ２００６ ２００５ ２００６ s .e .d G Y G倡 YDM Intake ( kg/ d) １９ .９ ２０ .６ １４ .８ １４ .１ １８ .３ １４ .２ ２ .４６ 倡倡倡 倡 NSC１８ :２ Intake ( g / d) ７８ .６ ８６ .９ ５２ .１ ５０ .８ １０９ ８４ .２ １１ .１４ 倡倡倡 报 NSC１８ :３ Intake ( g / d) ３７６ ３６１ ３３５ ２７８ ３２０ ２２６ ４６ .０ 倡 倡倡 NSMilk Yield ( kg/ d) ２４ .０ ２５ .０ ２０ .９ ２１ .７ ２２ .２ ２５ .８ ０ .８８ 倡倡倡 报 NSMilk C１８ :２ ( g / d) ８ .４０ ９ .７５ ８ .１５ ８ .６８ ８ .６６ ９ .８０ ０ .３３７ 倡 倡 NSMilk C１８ :３ ( g / d) ５ .５２ ６ .２５ ５ .２３ ５ .６４ ４ .４４ ５ .１６ ０ .２０４ 倡倡 倡倡 NSConversion C１８ :２ ( ％ ) １０ .７ １１ .２ １５ .６ １７ .１ ７ .９４ １１ .６ ３ .０３ 倡 NS NSConversion C１８ :３ ( ％ ) １ .４７ １ .７３ １ .５６ ２ .０３ １ .３９ ２ .２９ ０ .４４４ NS 报 报Conclusion Grass species and year can influence the intake and milk output of C１８ PUFA . Differences in degree of cell damagemay also affect the extent of biohydrogenation of C１８ PUFA in different grass species .ReferencesKim et al ２００８ Investigation of the effect of grass species on the release of cell contents during bolus formation . Proceedings o fthe British Society o f Animal Science . In press .Lee MRF , Jones , EL , Moorby , JM , Humphreys , MO , Theodorou , MK , MacRae , JC , Scollan , ND . ２００１ . Productionresponses from lambs grazed Lolium perenne selected for an elevated water‐soluble carbohydrate concentration . AnimalResearch ５０ : ４４１‐４４９ .Payne , R .W . , Murray , D .A . , Harding , S .A . , Baird , D .B . , Soutar , D .M .２００２ . Genstat 眘 for WindowsTM (８th Edition)Introduction . Ox f ord : VSN International .

Milk C18 Polyunsaturated Fatty Acids from Cows Grazed on Perennial Ryegrass, Tall Fescue or Timothy Grass Swards

https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=3517&context=igc

Milk C18 Polyunsaturated Fatty Acids from Cows Grazed on Perennial Ryegrass, Tall Fescue or Timothy Grass Swards

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