Finished Last updated: 24.11.2016
End: jun 2017
Start: jan 2013
Status Concluded
Start - end date 07.01.2013 - 30.06.2017
Project manager Håvard Steinshamn
Total budget 3875000

Publications in the project

To document

Abstract

Globalt representere husdyrproduksjon 14,5 % av antropogene klimagassutslipp, mens landbruket i Norge står for tilsvarende 9 %. Innenfor husdyrproduksjon kommer den største andelen av klimagassutslippene fra metanutslipp hos melkekyr. Dette skyldes den mikrobielle fermenteringen i vomma, som medfører et overskudd av hydrogen. Metanogene bakterier bruker hydrogen som et substrat, og sluttproduktet er metan. Mengde frie hydrogenmolekyl er styrt gjennom produksjonen av eddiksyre, smørsyre og propionsyre. Hensikten med denne oppgaven var å undersøke om tre ulike beitemetoder hadde en påvirkning på metanutslipp og fôropptak hos melkekyr. Metanproduksjonen ble målt ved hjelp av SF6 metoden. Metoden går ut på at du bruker en kapsel med kjent frigjøringsrate som en referanse for å beregne metanproduksjonene. Prosjektet hadde to perioder, en om våren og en om sensommeren. Hypotesen om at stripebeiting vil føre til mindre metanutslipp ble ikke bekreftet. Selv om min studie ikke fikk påvist at ulike beitemetoder påvirker metanutslipp, kan det likevel ikke utelukkes da resultatene for beregnet metanproduksjon var varierende og upresise. Metanutslippet variert fra 263 g/dag til 315 g/dag gjennom forsøket. Melkeproduksjonen var høyest om våren og gikk ned med noen kilo til sensommeren, generelt sett fulgte også fôropptaket denne trenden. Det ble heller ikke påvist at de ulike beitemetodene hadde en effekt på melkeproduksjonen og fôropptaket. Det har i tidligere studier blitt vist at SF6 metoden gir store variasjoner i beregning av metanutslipp og at den er noe upresis, noe som denne studien også fant. Det har blitt antatt at firgjøringsrate av SF6 er konstant, men nyere studier har påvist at dette er feil.

Abstract

We assessed milk production with 24 mid-lactation Norwegian Red dairy cows on a spring pasture dominated by timothy (Phleum pratense) for a period of 21 days using three pasture allocation techniques (n=8). Cows received weekly allowances at once (7 day-set-paddocking; 7SP), grazed 1/7 of 7SP allowance each day (daily-strip-grazing; 1SG), or grazed like 1SG but also had access to the previously grazed part of the paddock (daily-forward-grazing; 1FG). We hypothesized that 7SP would deteriorate sward quality and quantity over the grazing days whilst the other two treatments would provide balanced pasture quality and intake. These changes were expected to result in differences in milk yield and its components. However, changes in sward chemical composition (e.g. neutral netergent fiber, crude protein) over the grazing days in each week were not different among treatments (treatment × grazing day; P>0.05). Furthermore, no effect of treatments on milk yield and its components was observed. Nonetheless, the effects of grazing days over a week on milk yield and components were different among treatments (treatment × grazing day; P<0.05). These treatment by grazing day interaction effects, in the absence main effect of treatment, could be due to fluctuations in daily DMI among treatments over the grazing days in each week.

Abstract

We assessed milk production with 24 mid-lactation Norwegian Red dairy cows on a spring pasture dominated by timothy (Phleum pratense) for a period of 21 days using three pasture allocation techniques (n=8). Cows received weekly allowances at once (7 day-set-paddocking; 7SP), grazed 1/7 of 7SP allowance each day (daily-strip-grazing; 1SG), or grazed like 1SG but also had access to the previously grazed part of the paddock (daily-forward-grazing; 1FG). We hypothesized that 7SP would deteriorate sward quality and quantity over the grazing days whilst the other two treatments would provide balanced pasture quality and intake. These changes were expected to result in differences in milk yield and its components. However, changes in sward chemical composition (e.g. neutral netergent fiber, crude protein) over the grazing days in each week were not different among treatments (treatment × grazing day; P>0.05). Furthermore, no effect of treatments on milk yield and its components was observed. Nonetheless, the effects of grazing days over a week on milk yield and components were different among treatments (treatment × grazing day; P<0.05). These treatment by grazing day interaction effects, in the absence main effect of treatment, could be due to fluctuations in daily DMI among treatments over the grazing days in each week.