Methane emissions of dairy cows cannot be predicted by the concentrations of C8:0 and total C18 fatty acids in milk

• DOI: 10.1071/an14292
• Publication Date: 2014-12-05T00:10:18Z
• Authors: S. R. O. Williams; P. J. Moate; M. H. Deighton; M. C. Hannah; W. J. Wales
• Keywords: Methane Emissions; Concordance correlation coefficient; Linear relationship

Methane (CH4) emissions from dairy cows are technically difficult and expensive to measure. Recently, some researchers have found correlations between the concentrations of specific fatty acids in milk fat CH4 that could obviate need for direct measurement. In this research, data on individual cow concentration caprylic acid (C8:0) total C18 were collated eight experiments involving 27 forage-based diets 246 Holstein-Friesian cows. Linear regressions both C8:0 produced published used calculate 95% prediction regions a new observation. The proportion observed methane fell outside region was 27.6% model 26.3% model. Neither predicted emission well with Lin’s coefficient concordance less than 0.4 Nash–Sutcliffe efficiency approximately zero models. addition, general linear analysis showed significant differences their intercepts (P < 0.001) slopes 0.001). It is concluded relationships tested cannot be accurately predict when fed wide range diets.