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The climate-efficient dairy cow: Effect of feed intake, nutrient manipulation, and individual cow phenotype on enteric methane

Publikation: Bog/antologi/afhandling/rapportPh.d.-afhandling


Dairy production generates essential nutrients, but microbial fermentation in the rumen of dairy cows results in a considerable amount of methane, a potent greenhouse gas, which is released into the atmosphere. Is it possible to have climate-efficient dairy cows, with reduced methane emission, while retaining the benefits of dairy production? Enteric methane emission from dairy cows can be reduced by improving feed efficiency, through manipulation of dietary nutrients, and by genetic selection of lower emitting animals. In this dissertation different aspects are addressed: 1) a novel system involving 3D cameras to measure feed intake, was validated, as feed intake is essential to understand feed efficiency; 2) methane production was quantified from cows fed diets with manipulated nutrient composition, either by the type and source of carbohydrate, or by the source and concentration of fat; 3) between-cow variation response in methane emission was investigated in relation to methane mitigation diets; 4) the explanatory power of individual and grouped performance measures was quantified on between-cow variation in enteric methane production. The 3D cameras were assessed with cross-validation, and an error in feed intake measurements below 10% was found. The relationship between the volume measured from 3D cameras, and the weight measured from weighing scales, was tested for curvilinear effect, and for the effect of the push of the feed, but neither of these effects reduced the error when cross-validating the model. The effects of the type of dietary carbohydrate from silages and concentrates were not additive. Grass-clover silage and maize silage were tested with barley and dried beet pulp, and while barley compared to dried beet pulp decreased methane emission in cows fed maize silage, the emission did not decrease in cows fed grass-clover silage. Dietary fat reduced methane emission, when cracked rapeseed and palm kernel fatty acids were tested at different dietary concentrations. Cows fed rapeseed were able to decrease methane emission without compromising their productivity, unlike cows fed palm kernel, where a further decrease in methane emission was accompanied by a loss in productivity. Finally, cows responded differently to methane reducing dietary treatments. Lower methane emitting cows reduced methane emission more than high methane emitting cows did. The between-cow variation in methane production was explained best by dry matter intake when considering individual performance measures (milk yield, body weight, and milk nutrients), and grouping the performance measures did increase the explanatory power, but this increase wasnot considered sufficient to justify the use of grouped measures besides dry matter intake. In conclusion, there are opportunities to promote the climate-efficient dairy cow by measuring feed intake, manipulating the diet, selecting low methane emitting phenotypes, but optimization of these strategies requires further investigation.
ForlagAarhus University
Antal sider178
ISBN (Trykt)978-87-94253-60-4
StatusUdgivet - 3 nov. 2023

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