Kenyon, Paul R.

Morris, Stephen T.

Mulvaney, F. J.

West, D. M.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Effect of High and Low Pasture Allowance during Pregnancy on Ewe Lamb Pregnancy Performance Paul R. Kenyon Massey University, New Zealand F. J. Mulvaney Massey University, New Zealand Stephen T. Morris Massey University, New Zealand D. M. West Massey University, New Zealand 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/21/9-1/9 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 ]25　 瞯Grasslands/Rangelands Production Systems——— Livestock Production SystemsEffect of high and low pasture allowance during pregnancy on ewe lamb pregnancy performanceP .R .K enyon ,F .J .Mulvaney ,S .T .Morris and D .M .WestInstitute o f Veterinary ,A nimal and Biomedical Sciences ,Massey University ,Priv ate Bag 11‐222 ,Palmerston North ,NewZealand .E‐mail : p .r .kenyon＠ massey .ac .nzKey words : hogget ,lamb grow th ,nutritionIntroduction It is established that breeding ewe lambs ( ８‐９ months of age ,hogget ) can negatively affect their １８‐monthliveweight and breeding performance ( Kenyon et al .２００７ ) .Therefore the aim of any ewe lamb breeding regimen should be toensure they gain liveweight during their first pregnancy .However ,under housed ,concentrate feeding conditions high totalliveweight gains in pregnancy have been associated with increased fetal loss ,light lamb birthweight and lower lamb survivalrates to weaning ( Wallace et al .２０００ ) . The effects of ewe lamb liveweight gains during pregnancy under pastoral grazingsystems has not been thoroughly examined in New Zealand .Materials and methods In study one ,ewe lambs were randomly allocated to one of three total liveweight gain regimens beginning５ days after breeding . These included �Low�( n ＝ ８０ ) ,�Medium�( n ＝ ８０ ) and �High�( n ＝ ８０ ) total liveweight gains inpregnancy . Average daily gains were ６０ ,１３０ and ２３０g / d respectively in pregnancy . In study two ,two total liveweight gainregimens began four days prior to breeding and these included �Medium�( n ＝ １６５ ) and �High�( n ＝ １６５ ) ,which achievedaverage gains of １３０ and ２００ g / d respectively in pregnancy . In both studies ewe lambs were offered perennial ryegrass( Lolium .perenne) and white clover ( T ri f olium .repens ) mixed swards . The liveweight changes in the pregnancy period wereachieved by regular weighing and adjustment being made to the grazing area offered . The ewe lambs were scanned forpregnancy status in mid‐to late‐pregnancy to determine pregnancy loss . Liveweights of lambs born were measured at birth andweaning and the young dams were also re‐weighed at the weaning of their lambs . In both studies ewe lamb treatments weremerged and managed as one in lactation .Liveweight measures of the lambs and young dam were analysed using the GeneralisedLinear Model procedure in SAS ( SAS ,２００５) . Pregnancy loss and lamb survival were analysed using the GENMOD procedurefor categorical data in SAS .Results In study １ ,a greater ( P ＜ ０ .０５) percentage of �Low�(３２ ％ ) and�High�( ２８％ ) ewe lambs lost pregnancies comparedto their �Medium�counterparts (３％ ) . Lambs born to �Low�ewe lambs were lighter ( P ＜ ０ .０５) at birth and weaning ( ３ .５ ±０ .１６ and １８ .１ ± １ .０１ kg respectively) than those born to�Medium�and�High�ewe lambs (４ .０ ± ０ .１９ ,２０ .６ ± ０ .７６ and ４ .０ ±０ .１９ and ２１ .８ ± ０ .９８ kg respectively ) . They also displayed lower ( P ＜ ０ .０５ ) survival rates to weaning .Lamb born to�Medium�and�High�treatment groups did not differ in birthweight ,weaning weight or survival to weaning . At the weaningof their lambs ,�High�treatment ewe lambs were heavier ( ５５ .８ ± １ .０７ kg ,P ＜ ０ .０５ ) than both �Medium�( ４７ .９ ± ０ .９０ kg )and �Low�(４５ .２ ± １ .０７ kg ) ewe lambs ,which did not differ . In study ２ ,ewe lamb treatment had no effect on pregnancy loss ,lamb weight at birth or weaning or lamb survival . At the weaning of their lambs ,�medium�liveweight gain ewes were lighter( P ＜ ０ .０５) than�High�ewes (４８ .９ ± ０ .９ vs ５７ .９ ± ０ .８ kg repectively ) .Conclusions The results of study one suggests that pregnant ewe lambs should be managed to avoid relatively low liveweightgains in pregnancy . Failure to do so will have adverse consequences for both the young dam and her offspring . In both studyone and two ,newborn lamb performance to weaning did not differ between those born to ewe lambs on either of the�Medium�or �High�liveweight gain regimens suggesting no advantage of a relatively high liveweight gain . However ,from the perspectiveof the young dam ,the higher liveweight gains in pregnancy resulted in heavier weights at weaning . A heavier young dam at theweaning of her lambs is more likely to achieve a suitable １８‐month breeding weight . Interestingly in study one ,high liveweightgains were associated with increased pregnancy loss which agrees with the findings of Wallace et al . ( ２０００ ) under houseconcentrate feeding conditions . This relationship was not observed in study two and warrants further examination to determineif there is an absolute minimum liveweight gain required to observe increased fetal loss .ReferencesKenyon PR ,Proctor L ,Morris ST ,West DM ( ２００７ ) Lambing as a hogget negatively affects two‐tooth ewe reproductiveperformance . In press accepted Livestock science .Wallace JM ( ２０００ ) Nutrient partitioning during pregnancy : adverse gestational outcome in overnourished adolescent dams .Proceedings o f the Nutrition Society ,５９ ,１０７‐１１７ .

Effect of High and Low Pasture Allowance during Pregnancy on Ewe Lamb Pregnancy Performance

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Effect of High and Low Pasture Allowance during Pregnancy on Ewe Lamb Pregnancy Performance

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