Abstract

Enteric methane (CH4) emissions vary between individual cows, and this variation is attributed to both animal and dietary factors. In addition, measurement technique of in vivo CH4 emissions from individual animals still represents a major challenge for successful emissions mitigation strategies. This thesis investigated the contribution of different factors to between-animal variation in CH4 production, in order to improve the current knowledge of its biological basis. In a study comparing on-farm systems for measuring CH4 emissions from large numbers of animals and the variation between individual animals, the GreenFeed system was used as the normal set-up (flux method) or modified to mimic gas analysers systems based on CH4 concentrations (sniffer system) to measure CH4 emissions. Measurements taken by the GreenFeed system proved be more reliable than those made by the simulated sniffer method. The GreenFeed data were consistent with literature values determined in respiration chambers, while the sniffer method were poorly correlated to flux method values and were not significantly related to either feed intake or milk yield. Despite GreenFeed being a spot sampling method, it proved to be a promising tool for ranking cows as high and low CH4 emitters. A meta-analysis based on an individual cow dataset investigating the effects of between-cow variation and related animal variables on predicted CH4 emissions from dairy cows. Between-cow variation in fermentation pattern are not likely be the major factor influencing predicted in vivo CH4 emissions. Variation and repeatability for volatile fatty acid concentrations were greater for ruminal concentrations than molar proportions, indicating strong control by the individual cow. Digestion kinetics variables were more repeatable than rumen fermentation or microbial synthesis, as a result of variations in passage rate. In studies in which late-cut silage and rolled barley were gradually replaced with early-cut silage in the diet of dairy cows, production responses and in vivo CH4 emissions were studied in 16 intact lactating cows and possible physiological mechanisms were assessed in four rumen-cannulated cows. Improvements in forage quality by graded addition of early-cut silage was an effective strategy to reduce concentrate supplementation, without compromising performance or increasing CH4 emissions in lactating dairy cows. Differences in intake between treatments were partly compensated by differences in silage digestibility.

Keywords

dairy cattle; methane yield; between-cow variation; repeatability

Published in

Acta Universitatis Agriculturae Sueciae
2017, number: 2017:43
ISBN: 978-91-576-8859-0, eISBN: 978-91-576-8860-6
Publisher: Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences

SLU Authors

• Hernando Cabezas Garcia, Edward

  • Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Animal and Dairy Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/81014