Kennedy, Emer

O\u27Donovan, M.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Effect of Restricted Access Time to Pasture on Dairy Cow Milk Production, Grazing Behaviour and Dry Matter Intake Emer Kennedy Teagasc, Ireland M. O'Donovan Teagasc, Ireland 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/21/9-1/35 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 ]51　 瞯Grasslands/Rangelands Production Systems——— Livestock Production SystemsEffect of restricted access time to pasture on dairy cow milk production ,grazing behaviour anddry matter intakeE .Kennedy , M .O摧DonovanTeagasc ,Dairy Production Research Centre ,Moorepark ,Fermoy ,Co .Cork ,I relandE‐mail : Emer .K ennedy＠ teagasc .ieKey words : grazing ,dairy cows ,restricted access ,grazing behaviour ,milk productionIntroduction Irish dairy farmers are now targeting a ３００‐day grazing season in order to increase the proportion of grazed grass inthe diet of the dairy cow and optimise the economical efficiency of their business . However ,inclement weather conditions inearly spring and late autumn can reduce the number of days at pasture for lactating animals ,allowing animal摧s restricted accessto pasture during these periods may be a method of extending the grazing season . The aim of this experiment was to examinethe effect of restricting pasture access time on dairy cow milk production and composition ,bodyweight and body condition scorechange ,dry matter intake and grazing behaviour .Materials and methods Fif ty‐two ( １９ primiparous and ３３ pluriparous ) Holstein‐Friesian dairy cows ( mean calving date‐１７August) ,were balanced on ４ weeks pre‐experimental milk yield ( ２３ .８ ; s .d .３ .８２ kg ) ,parity (２ .１ s .d .１ .３２ ) ,milk fat ( ４１ .３ ;s .d .６ .９４ g / kg ) ,protein (３４ .０ ; s .d .２ .６２ g / kg ) and lactose content (４５ .７ ; s .d .１ .６１ g / kg ) ,body weight (５９１ ; s .d .６１ .７ kg )and body condition score (３ .００ ; s .d .０ .４５３) and randomly assigned to a four treatment study ( n ＝ １３) f rom ７ March to ６ April２００７ . The four treatments were : full‐time access to pasture ( ２４ ; control) ; ９ hours pasture access between milkings ( ９ ) ; ２three‐hour periods of pasture access af ter both milkings ( ２ × ３ ) ; ２ four‐and‐a‐half hour periods of pasture access after bothmilkings (２ × ４ .５ ) . All treatments were offered a daily herbage allowance of １５ .５ kg DM /cow /day and ３ kg DM ofconcentrate/ cow / day . Fresh herbage was allocated daily ,no supplementary feed was offered to animals when removed frompasture . T reatment groups grazed separately for the duration of the study . Pre and post grazing sward heights were measureddaily .Milk yield was recorded daily ,milk composition and bodyweight were measured weekly .Dry matter intake ( DMI) andgrazing behaviour were recorded on the final week of the study .All animal parameters were analysed using covariate analysis .The variables included in the model were lactation number , treatment ,days in milk and the appropriate pre experimentalvariables were also included .Results and discussion The pre‐grazing herbage mass offered to all treatments was approx .１２８２ kg DM / ha and sward OMD was８６４ g / kg ,indicating high quality swards conducive to high DMI . Swards where animals had full time and ２ × ４ .５ hours accessto pasture had the lowest post grazing heights (３ .５ cm) . Following the experimental period there were no differences in mostmilk production parameters however reducing access time to ２ three‐hour periods significantly reduced ( P ＜ ０ .０５) milk proteinconcentration . Furthermore ,restricting pasture access time to one period of ９ hours significantly reduced DMI ( P ＜ ０ .０５ )compared to the control treatment . Restricting pasture access time resulted in much greater grazing efficiency as animals fromthe ９ ,２ × ３ and ２ × ４ .５ treatments spent a greater proportion of their time at pasture grazing ( ８０ ,９７ and ７８％ ,respectively )than control animals (３８％ ) .Conclusions From this study it is apparent that restricting access to pasture is an innovative method of increasing the number ofdays at pasture during periods of inclement weather . However ,for optimal results total access time should be split into twodistinct periods and be at least four and a half hours long .Table 1 E f f ect o f pasture access time on milk y ield ,milk composition ,dry matter intake and graz ing time .２４ 耨９ "２ × ３ 鞍２ × ４ 适.５ Rse SigMilk yield ( kg / cow ) ２２ 妹.０ ２２  .６ ２１ T.４ ２１ 湝.７ ０ 抖.７７ NSMilk fat content ( ％ ) ４ 晻.１２ ４ 葺.１８ ４ &.１８ ４ n.０４ １ 煙.５５７ NSMilk protein content ( ％ ) ３ 儍.５５a ３ 揪.４２ab ３  .３２b ３ O.４３ab ０ 煙.７４９ 倡Body weight change ( kg / day) ‐１ い.２８ ‐１ 眄.２８ ‐１ 5.４０ ‐１ }.２１ ０ 煙.１７１ NSTDMI ( kg / cow /day) １７ 北.４a １５ �.７b １６ 5.６ab １６ 垐.３b ０ 抖.５１ 倡Grazing Time (mins/ day) ５４０a ４３１b ３４９c ４２５b ２２ 滗.２ 倡倡倡NS ＝ Non significant ,倡倡倡 ＝ P ＜ ０ .００１ ,倡 ＝ P ＜ ０ .０５ . abc values in the same row not sharing a common superscript are significantly differentTDMI — Total Dry Matter Intake

Effect of Restricted Access Time to Pasture on Dairy Cow Milk Production, Grazing Behaviour and Dry Matter Intake

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Effect of Restricted Access Time to Pasture on Dairy Cow Milk Production, Grazing Behaviour and Dry Matter Intake

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