Boland, Tommy M.

Delaby, Luc

McEvoy, Mary

O\u27Donovan, M.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Two Techniques to Measure Herbage Intake of Grazing Dairy Cows Mary McEvoy Teagasc, Ireland M. O'Donovan Teagasc, Ireland Tommy M. Boland University College Dublin, Ireland Luc Delaby INRA, France 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/21/9-1/45 The 21st International Grassland Congress / 8th 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. 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅱ 　 瞯 ]61　 瞯Grasslands/Rangelands Production Systems——— Livestock Production SystemsTwo techniques to measure herbage intake of grazing dairy cowsM .McEvoy 1 ,2 ,M .O�Donov an1 ,T .M .Boland2 and L .Delaby 31 Dairy Production Research Centre ,Teagasc ,Moorepark ,Fermoy ,Co .Cork ,I reland .2 School o f A griculture ,Food Scienceand Veterinary Medicine ,UCD ,Bel f ield ,Dublin 4 ,I reland .3 INRA ,UMR Production du L ait ,35590 ,St Gilles ,France .E‐mail : mary .mcevoy＠ teagasc .ieIntroduction Dry matter intake (DMI) is a major factor influencing milk production in dairy cows .The level of accuracy withwhich intake is measured is highly variable and dependant on the method used .Smit et al . ,(２００５) concluded that the n‐alkanetechnique is the best method to estimate herbage intake of individual grazing animals .Materials and methods Seventy‐two spring calving Holstein Friesian dairy cows were randomly assigned to a six treatment ( n ＝１２ ) grazing study for a ７７ day period ( ２０ Feb .‐７ May) .The treatments were : ( L０) １３ kg dry matter (DM ) / cow daily herbageallowance (DHA) ＋ ０kg conc . ; ( L３ ) １３kg DM /cow DHA ＋ ３kg DM /cow conc . ; ( L６ ) １３kg DM /cow DHA ＋ ６kg DM /cowconc . ; ( H０) １７kg DM /cow DHA ＋ ０kg conc . ; ( H３) １７kg DM /cow DHA ＋ ３kg DM /cow conc . ; ( H６ ) １７kg DM /cow DHA＋ ６kg DM /cow conc .Each group grazed separately for the duration of the experiment .Fresh herbage ( ＞ ４cm ) was allocateddaily .DMI was measured on three occasions during the experimental period‐weeks ３ ,６ and １０ using the n‐alkane technique asdescribed by Dillon et al . ( １９８９ ) . The alkane concentration of the dosed pellets , faeces , herbage and concentrate weredetermined and used to calculate grass DM intake ( GDMI) of each animal .The HR measurements were averaged across weeks２ ,３ ,５ ,６ ,９ and １０ of the experiment .Herbage mass and sward density were measured twice weekly by cutting two strips pergrazing area .Pre and post‐grazing sward heights were measured daily using an electronic plate‐meter .Herbage removed wascalculated using the following equation :( Pre‐post height) × density × area/ ( no .cows × １００００ ) .The n‐alkane intakes were analysed using covariate analysis .Thevariables included were milk yield and bodyweight .HR data were analysed using analysis of variance .The factors included inboth models were DHA ,conc .level and their interactions .Linear regression analysis was used to determine the degree ofassociation between the two methods when estimating GDMI .　 　 Figure 1 L inear regression equation to determine the degree o fassociation between the two methods f or estimating grass drymatter intake .Results and discussion Results presented are averagedfor the three intake measurement periods ( Table １ ) .DHA ( P ＜ ０ .００１ ) and concentrate ( P ＜ ０ .０１ ) had asignificant effect on GDMI with both methods .Figure１ shows the association between the two methods .Conclusions Daily measurements of pre and post‐heights will allow more frequent estimates when usingthe HR method .Pre‐height should not be excessivelyhigh ,as this may reduce the accuracy of plate‐meterreadings if herbage is lodging .A high level of herbageutilisation is recommended for accurate results ( range１ .０９‐０ .８４ in this study ) .The HR method is usefulwhen rapid estimates of GDMI are required .The n‐alkane technique is recommended for estimation ofindividual animal herbage intakes .Table 1 Sward variables and grass dry matter intakes based on group averages f or three intake measurement periods (between６ March and ３０ A p ril) .L０ ЁL３  L６ dH０ 烫H３ +H６ 妸Rse DHA Conc .Pre height ( cm) ９ [.７ ９ 汉.７ ９  .７ ９ w.８ ９ 照.８ ９ 4.８ ０ |.３０ NS NSPost height ( cm) ３ J.５a ３ Ζ.８b ４  .３c ４ Y.４cd ４ 侣.７d ５ #.０e ０ |.１２ 倡倡倡 倡倡倡Density ２２９ 贩２２９  ２２９ t２３５ 佑２３５ 1２３５ 悙３ |.６９ NS NSHerbage removed ( kg DM ) １３ a.９a １３ 浇.０b １２  .０c １５ {.６d １４ 儋.８d １３ ,.６ab ０ |.３０ 倡倡倡 倡倡倡n‐Alkane GDMI ( kg DM ) １３ a.６a １３ 靠.９a １２  .５a １５ z.８b １５ 儋.５b １３ :.４a ０ |.７６ 倡倡倡 倡倡( n‐alkane‐HR method) ( kg DM ) ‐０ k.３ ０ 汉.９ ０  .５ ０ w.２ ０ 照.７ ‐０ D.２Herbage removed refers to that measured using the HR method ; n‐Alkane GDMI ＝ Grass dry matter intake measured using then‐alkane technique .abc values in the same row not sharing a common superscript are significantly different .

Two Techniques to Measure Herbage Intake of Grazing Dairy Cows

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Two Techniques to Measure Herbage Intake of Grazing Dairy Cows

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