Methane emission in Jersey cows during spring transition from indoor feeding to grazing

摘要

In this study we evaluated the effects of gradual transitioning from indoor winter-feeding to outdoor grazing, 8 to 11 h daily, on methane emission and milk yield in an organic Jersey herd in Denmark. A total of 151 mixed-parity lactating Jersey cowswith free access to automated milking stations (AMS) were monitored from 30 d prior to barn release until 23 d post release. During each visit to the AMS, milk yield was measured and logged together with date and time. Methane (CH4) monitoring equipmentwas installed in the feed troughs of AMS. Methane and carbon dioxide (C0_2) were measured continuously in ppm using a non-invasive 'sniffer' method, and the CH_4/C0_2 ratio was used as emission trait. This trait was averaged over milking. Milk yield was19.4 kg d~(-1) in the indoor period and increased to 20.2 kg during grazing. A small increase (4%) in the CH4/C02 ratio at herd level was found when comparing indoor period with grazing period, while the variation from day to day increased in the grazingperiod compared with the indoor period. The correlation between indoor and grazing period was very high; however, slight re-ranking of animals was detected.