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Methods

Title:		Repeatability and ranking of long-term enteric methane emissions measurement on dairy cows across diets and time using GreenFeed system in farm-conditions
Author(s):		Coppa M; Jurquet J; Eugene M; Dechaux T; Rochette Y; Lamy JM; Ferlay A; Martin C;
Address:		"Independent researcher at Universite Clermont Auvergne, INRAE, VetAgro Sup, UMR 1213 Herbivores, F-63122 Saint-Genes-Champanelle, France. Institut de l'Elevage, 42 rue Georges Morel CS 60057, 49071 Beaucouze Cedex, France. Universite Clermont Auvergne, INRAE, VetAgro Sup, UMR 1213 Herbivores, F-63122 Saint-Genes-Champanelle, France. Institut de l'Elevage, Maison Nationale des Eleveurs - 149 Rue de Bercy, 75595 Paris Cedex 12, France. Ferme experimentale des Trinottieres, 49140 Montreuil-sur-Loir, France. Universite Clermont Auvergne, INRAE, VetAgro Sup, UMR 1213 Herbivores, F-63122 Saint-Genes-Champanelle, France. Electronic address: cecile.martin@inrae.fr"
Journal Title:		Methods
Year:		2021
Volume:		20201128
Issue:
Page Number:		59 - 67
DOI:		10.1016/j.ymeth.2020.11.004
ISSN/ISBN:		1095-9130 (Electronic) 1046-2023 (Linking)
Abstract:		"The aims of this work were to study on dairy farm conditions: i) the repeatability of long-term enteric CH(4) emissions measurement from lactating dairy cows using GreenFeed (GF); ii) the ranking of dairy cows according to their CH(4) emissions across diets. Forty-five Holstein lactating dairy cows were randomly assigned to 3 equivalent groups at the beginning of their lactation. The experiment was composed of 3 successive periods: i) pre-experimental period (weeks 1 to 5) in which all cows received a common diet; ii) a dietary treatment transition period (weeks 6 to 10); and iii) an experimental period (weeks 11 to 26) in which each group was fed a different diet. Experimental diets were formulated to generate more or less CH(4) production: i) a diet based on ryegrass silage and concentrates, low in starch and lipid, designed to induce high CH(4) emissions (CH4+); ii) a diet based on maize silage and concentrates, rich in starch, designed to induce intermediate CH(4) emissions (CH4int); iii) a diet based on maize silage and concentrates, rich in starch and lipid, designed to induce low CH(4) emissions (CH4-). Gas emissions were individually measured using GF systems. Repeatability of gas emissions, dry matter intake (DMI) and dairy performances measurements was calculated from data averaged over 1, 2, 4, and 8 weeks for each animal. Hierarchical cluster analysis was performed to rank individual animals according to their CH(4) emissions. No significant differences were observed for daily CH(4) emissions (g/day) among diets, because of lower DMI of CH4+ cows. When CH(4) emissions were referred to units of DMI or milk, the differences among diets emerged as significant and persistent over the observed period of lactation. Repeatability values of gas emissions measurements were higher than 0.7 averaged over 8 weeks of measurement, but still higher than 0.6 for CH(4) g/day, CO(2) g/day, CH(4) g/kg milk, and CH(4)/CO(2) even averaging only 2 weeks of measurement. The repeatability of CH(4) emissions measurement was systematically lower than those of DMI or dairy performance parameters, like milk and FPCM yield, irrespective of the averaged measurement period. The dairy cow ranking was not stable over time between all individuals or within any of the diets. In our experimental conditions, the GF performance in the long term can be considered reliable in differentiating dairy herds by their CH(4) emissions according to diets with different methanogenic potential, but did not allow the ranking of individual dairy cows within a same diet. Our data highlight the importance of phenotyping animals across environment in which they will be expected to perform"
Keywords:		"Animals Biological Variation, Population Cattle Ecological Parameter Monitoring/*methods/statistics & numerical data Farms/statistics & numerical data Female Gastrointestinal Microbiome/*physiology Greenhouse Effect/*prevention & control Lactation/metabol;"
Notes:		"MedlineCoppa, Mauro Jurquet, Julien Eugene, Maguy Dechaux, Terrence Rochette, Yvanne Lamy, Jean-Michel Ferlay, Anne Martin, Cecile eng Research Support, Non-U.S. Gov't 2020/12/01 Methods. 2021 Feb; 186:59-67. doi: 10.1016/j.ymeth.2020.11.004. Epub 2020 Nov 28"