Individual variation and repeatability of fibre digestibility, gas emissions and feed efficiency and in beef heifers

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Source: Beef Farmers of Ontario

Executive Summary

The objectives of this project will help identify traits in the cow/calf industry associated with improved feed efficiency and reduced enteric methane emissions in forage-fed animals. Traditional feed efficiency measures (ie RFI) are challenging in forage-fed animals, due to low accuracy, re-ranking, and cost of measurement.

Residual feed intake in particular was developed on highly digestible diets and may underestimate the impact of individual animal variability & repeatability in digestibility and gas emissions (CH4, CO2, O2). Characterizing this variability and adaptability to less digestible forages may lead to improved identification of efficient animals. In addition, beef cattle account for 80% of total agricultural greenhouse gas emissions.

However, the majority of GHG data from beef cattle has been collected from Western Canada or confined feeding systems. Environmental and pasture conditions in Ontario differ greatly and therefore national average values for GHG emissions may also vary by region. In addition, climate change is expected to increase plant NDF, decreasing digestibility and increasing enteric methane emissions by 0.9% for every 1 degree increase in global temperature.

Therefore, reducing CH4 emissions, and associated feed digestibility also has positive impacts on environmental footprint of cattle production. Therefore, gas exchange (and associated indirect calorimetry calculations) and digestibility may prove to be a superior trait over only using RFI or feed conversion measures for the cow/calf sector, and in turn improve feed efficiency and the environmental footprint of cattle production.

Specific Project Area(s): Environmental Sustainability and Feed Efficiency 

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