Relationships between methane production and milk fatty acid profiles in dairy cattle

Abstract

There is a need to develop simple ways of quantifying and estimating CH4 production in cattle. Our aim was to evaluate the relationship between CH4 production and milk fatty acid (FA) profile in order to use milk FA profiles to predict CH4 production in dairy cattle. Data from 3 experiments with dairy cattle with a total of 10 dietary treatments and 50 observations were used. Dietary treatments included supplementation with calcium fumarate, diallyldisulfide, caprylic acid, capric acid, lauric acid, myristic acid, extruded linseed, linseed oil and yucca powder. Methane was measured using open circuit indirect respiration calorimetry chambers and expressed as g/kg dry matter (DM) intake. Milk FA were analyzed by gas chromatography and individual FA expressed as a fraction of total FA. To determine relationships between milk FA profile and CH4 production, univariate mixed model regression techniques were applied including a random experiment effect. A multivariate model was developed using a stepwise procedure with selection of FA based on the Schwarz Bayesian Information Criterion. Dry matter intake was 17.7±1.83kg/day, milk production was 27.0±4.64kg/day, and methane production was 21.5±1.69g/kgDM. Milk C8:0, C10:0, C11:0, C14:0 iso, C15:0 iso, C16:0 and C17:0 anteiso were positively related (P<0.05) to CH4 (g/kg DM intake), whereas C17:0 iso, cis-9 C17:1, cis-9 C18:1, trans-10+11 C18:1, cis-11 C18:1, cis-12 C18:1 and cis-14+trans-16 C18:1 were negatively related (P<0.05) to CH4. Multivariate analysis resulted in the equation: CH4 (g/kg DM)=24.6±1.28+8.74±3.581×C17:0 anteiso−1.97±0.432×trans-10+11 C18:1−9.09±1.444×cis-11 C18:1+5.07±1.937×cis-13 C18:1 (individual FA in g/100g FA; R2=0.73 after correction for experiment effect). This confirms the expected positive relationship between CH4 and C14:0 iso and C15:0 iso in milk FA, as well as the negative relationship between CH4 and various trans-intermediates, particularly trans-10+11 C18:1. However, in contrast with expectations, C15:0 and C17:0 were not related to CH4 production. Milk FA profiles can predict CH4 production in dairy cattle.This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.