PSXIV-12 - Genetic Selection Using Ecofeed Index Reduces Carbon Footprint in Lactating Dairy Cows

Abstract: Improvement in feed efficiency affects the carbon footprint of a dairy production system. The objective of this study was to determine the overall effect of using the EcoFeed index by STgenetics to reduce enteric methane, crop production and manure related emissions. Genomic estimated breeding values for residual feed intake (RFI) in lactating dairy cows were calculated using genetic parameters estimated for DMI, energy-corrected milk (ECM), body weight, and body weight change. A dataset containing phenotypic and genomic information on 639 lactating dairy cattle was used for the analysis. The dairy cattle were divided into low, medium and high EcoFeed classes. Genomic RFI class was determined based on animals being +/- ½ SD from genomic RFI. A life cycle assessment according to international standards (ISO 14040/44) and Livestock Environmental Assessment and Performance Partnership guidelines was conducted to calculate the carbon footprint of the three EcoFeed classes. Production of a kilogram of ECM emitted 0.94, 1.00 and 1.04 kg CO₂ equivalent (CO₂e) from high, medium and low EcoFeed classes, respectively during a 305-day lactation cycle. In all cases, manure management and enteric methane emissions contributed the most to the carbon footprint. The greater contributions from manure was due to assumption of manure being managed in a lagoon system that carries relatively greater emission factor compared with solid storage. Crop production contributed to 0.11, 0.12 and 0.13 CO₂e from high, medium and low EcoFeed classes, respectively. This is due to reduced amount of feed required in high and medium EcoFeed classes compared with the lower class because of efficiency gains. If high EcoFeed class dairy cattle were to be used in the US, there will be an estimated annual potential reduction of 10 billion CO₂e. Therefore, genomic selection is a powerful tool to reduce carbon footprint in dairy cattle.