Review: Selecting for improved feed efficiency and reduced methane emissions in dairy cattle

Abstract

It may be possible for dairy farms to improve profitability and reduce environmental impacts by selecting for higher feed efficiency and lower methane (CH4) emission traits. It remains to be clarified how CH4 emission and feed efficiency traits are related to each other, which will require direct and accurate measurements of both of these traits in large numbers of animals under the conditions in which they are expected to perform. The ranking of animals for feed efficiency and CH4 emission traits can differ depending upon the type and duration of measurement used, the trait definitions and calculations used, the period in lactation examined and the production system, as well as interactions among these factors. Because the correlation values obtained between feed efficiency and CH4 emission data are likely to be biased when either or both are expressed as ratios, therefore researchers would be well advised to maintain weighted components of the ratios in the selection index. Nutrition studies indicate that selecting low emitting animals may result in reduced efficiency of cell wall digestion, that is NDF, a key ruminant characteristic in human food production. Moreover, many interacting biological factors that are not measured directly, including digestion rate, passage rate, the rumen microbiome and rumen fermentation, may influence feed efficiency and CH4 emission. Elucidating these mechanisms may improve dairy farmers ability to select for feed efficiency and reduced CH4 emission.

Methane and Carbon Dioxide Emission of Beef Heifers in Relation with Growth and Feed Efficiency

“…Both the methane and the metabolizable energy of the diet depend on the digestion process in the rumen-an increased digestion can provide more nutrients for the animal metabolism, as well as increased enteric methane production when roughage diets are consumed. In the review of Richardson and Herd [41], digestibility was assumed to account for 10% of the variation in RFI on average in beef cattle, while Lovendahl et al [42], in their review of dairy cattle, concluded that between-cow variation in digestibility alone was too small to explain the observed variation in feed efficiency. Nonetheless, higher digestibility of DM or NDF was found in low-RFI as compared to high-RFI cattle in the studies of McDonnell et al [15] and Oliveira et al [17] with beef cattle and Olijhoek et al [43] with dairy Holstein cows.…”

Defining the optimal period length and stage of growth or lactation to estimate residual feed intake in dairy cows

“…A positive RFI value means feed intake is greater than expected and indicates an inefficient animal, whereas a negative value means intake is less than expected and indicates a more efficient animal. Research on methods to estimate RFI, the biological basis of its variation, and its utility in genomic selection of dairy cattle continues to evolve since Koch et al (1963) first introduced RFI as an estimate of metabolic efficiency of growing beef cattle (e.g., see reviews by Berry and Crowley, 2013;Connor, 2015;Løvendahl et al, 2018). Implementation of genomic selection for improved (reduced) RFI in dairy cattle has been proposed (Gonzalez-Recio et al, 2014;Pryce et al, 2014;VandeHaar et al, 2016), although present accuracy of genomic breeding values is generally low (≤0.4), in part due to limited availability of RFI phenotypes from genotyped individuals (Pryce et al, 2014).…”

Intégrer les changements d’échelle pour améliorer l’efficience des productions animales et réduire les rejets

“…Pour des femelles laitières, si les approches basées sur la CMJR semblent également pertinentes, elles nécessitent de longues périodes de mesures d'ingestion pour prendre en compte la dynamique de la lactation, même si les travaux récents montrent que les mesures en milieu de lactation sont les plus représentatives de l'ensemble du cycle. Le modèle de calcul des CMJR pour les vaches laitières utilise le lait et la composition du lait, le poids et de façon moins systématique les variations de poids ou d'état corporel pour tenir compte des variations des réserves (Løvendahl et al, 2018). L'utilisation de ces indicateurs montre une variabilité importante de la CMJR dans la plupart des espèces.…”

“…En pratique, la sélection permettrait de gagner de l'ordre de 10 % sur la consommation d'aliments pour des animaux en croissance, mais probablement moins sur les femelles laitières. La faible corrélation entre l'efficience calculée en début de lactation et celle observée sur toute la lactation (Fischer, 2017 ;Løvendahl et al, 2018). D'autres approches analogues basées sur la production résiduelle au lieu de l'ingestion résiduelle ont été proposées à partir de modèles destinés à expliquer la production (lait ou gain de poids) à partir de variables décrivant l'ingestion et le poids de l'animal.…”