|Title||Methane concentration phenotypes of dairy cows measured in automatic milking systems|
|Author(s)||Engelen, S. van; Bovenhuis, H.; Tol, van der, P.P.J.; Visker, M.H.P.W.|
|Event||6th Greenhouse Gas and Animal Agriculture Conference, Melbourne, 2016-02-16|
Animal Breeding and Genetics
Wageningen Institute of Animal ScienceWIAS
|Publication type||Poster (scientific)|
|Keyword(s)||Dairy cow - Methane - AMS - Infrared sensor|
|Abstract||The objective of this study was to explore methane (CH4) concentration phenotypes that can be used to perform genetic analyses on CH4 production of dairy cows.
Methane was measured with Fourier transformed infrared sensors twice per second during visits of automatic milking systems (AMS). Data were available for 549 Dutch dairy cows from 6 commercial farms with on average 66 AMS visits per cow. Mean and median of CH4 were calculated per AMS visit, for visits of at least 3 minutes. Data was analysed in ASReml 3.0 using the following model:
Yijkl = µ + date.herd.AMSijk + animall + eijkl
where Yijkl is the dependent methane concentration phenotype; µ is the general mean; date.herd.AMSijk is the combined fixed effect of date i, herd j, and AMS k; animal is the random effect of lth animal; and eijkl is the random residual. Resulting variance components were used to estimate the repeatability as the animal variance divided by the total, animal and residual, variance.
The coefficient of variation for mean CH4 concentration was 99 % and for median CH4 concentration it was 97 %. The repeatability was 0.27 ± 0.01 for mean CH4 concentration and 0.22 ± 0.01 for median CH4 concentration. Repeatabilities are in line with other studies exploring CH4 production and suggest variation in CH4 production between cows. We expect that part of that variation is due to the genetic differences between cows. We are currently evaluating whether quality-filtering of data is needed, exploring different additional CH4 concentration phenotypes, and extending our dataset with the aim to perform genetic analyses of CH4 production of dairy cows.