Estimation of CH4 emissions from milk MIR spectra using respiration chamber as reference technique


  • Vanlierde, A. , Gengler, N. , Soyeurt, H. , Grandl, F. , Kreuzer, M. , Khula, B. , Lund, P. , Olijhoek, D. . , Ferris, C. & Dehareng, F. (2017). Estimation of CH4 emissions from milk MIR spectra using respiration chamber as reference technique. Proceedings in: EAAP, Tallinn, August 2017,
Type Conference Proceedings
Year of conference 2017
Title Estimation of CH4 emissions from milk MIR spectra using respiration chamber as reference technique
Conference name EAAP
Conference location Tallinn
conference Date August 2017
Abstract Reducing the methane (CH4) emissions from dairy cows is a challenging aspect of the cattle breeding of today and tomorrow. In order to permit large scale studies focusing on genetics and management, an equation has been developed to estimate individual CH4 emission from milk MIR spectra. The existing equation is based on values obtained with the SF6 technique. However, the gold standard to measure CH4 is the respiration chamber (RC). Hence, the purpose of this work was to develop a new equation exclusively based on data collected with the RC technique and to compare its statistical performance (accuracy, robustness, etc.) with the existing SF6 equation. Daily CH4 linked with milk MIR spectra have been collected from Switzerland (60 data from 30 cows), Germany (115 data from 26 cows), Denmark (132 data from 19 cows) and Northern Ireland (24 data from 12 cows) yielding a total of 331 RC measurements from 87 cows. Cows were fed with different types of diets and were at variable lactation stages. The measured CH4 values ranged from 304 to 779 g/day with a mean of 504 g/day. The milk spectra were adjusted to take into account the days in milk. A fivefold cross-validation (CV) was performed to evaluate the robustness of the equation. The statistics of the equation based on RC measurements showed an R²cv of 0.62, a standard error of CV (SECV) of 60 g/day and the ratio performance deviation (RPD) was 1.6. In comparison, the equation based on 532 SF6 measurements (different countries and cows) showed an R²cv of 0.70, a SECV of 70 g/day and a RPD of 1.8. It appears that the SF6 equation seems to be more robust. It might be explained by the greater number of measurements, cows (165 vs. 87), lactation number and stage and different diets (pasture measurements are possible with SF6 technique). Thus, greater variability was included in the SF6 reference data set. Those results obtained with the gold standard technique (RC) confirm that it is possible to estimate CH4 emissions from milk MIR spectra.
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Authors Vanlierde, A., Gengler, N., Soyeurt, H., Grandl, F., Kreuzer, M., Khula, B., Lund, P., Olijhoek, D. ., Ferris, C., Dehareng, F.