Examining the Microbial Basis of Forage Digestion Efficiency in Beef Cattle

Project Title

Examining the Microbial Basis of Forage Digestion Efficiency in Beef Cattle


Dr. Robert Gruninger robert.gruninger@canada.ca

Dr. Gabriel Ribeiro (Co-lead), University of Saskatchewan Dr. Wade Abbott, Agriculture and Agri-Food Canada Dr. Greg Penner, University of Saskatchewan Dr. Arun Kommadath, Agriculture and Agri-Food Canada Mr. Rodrigo Ortega-Polo, Agriculture and Agri-Food Canada

Status Project Code
In progress. Results expected in March, 2025 FDE.07.20


Improving feed efficiency can help both reduce feed costs and reduce the environmental impact of feed cattle. There is a large variation between animals when it comes to feed efficiency. Residual feed intake (RFI) is one way to measure efficiency in cattle, but doesn’t work as well on grazing animals. Cattle that are feed efficient on a more highly digestible concentrate diet aren’t as efficient on high fiber forage diets. These researchers want to better understand why some animals are more efficient at digesting forages than others.  


  •  Determine if the microbial ecology of the rumen and/or hindgut varies between animals that differ in forage digestion efficiency
  • Identify key genes and/or microbes in high efficiency animals that are not present in low efficiency animals
  •  Determine if animal physiology and host metabolism is a bigger factor in feed digestion efficiency than the microbial processes in the gut.
  • Determine if efficiency rankings in animals change as a result of changes in feed composition and how might this relate to animal and/or microbial factors.

What they will do

64 beef heifers will be fed a high forage diet in growsafe bunks and total tract digestibility will be estimated. The eight heifers with the highest and eight with the lowest digestibility will be canulated and used in a metabolism study. In the metabolism study the 16 heifers will be fed high forage diets and rumen, urine, and fecal samples will be collected and analyzed for differences between the two groups. They will then use the same heifers to see if their ability digest feed remains the same if the diet is changed. Cattle will be fed either a grass hay or legume hay diet at 90% or 10% forage for each. In a third study they will use metagenomics to analyze the rumen and digestive tract microbial community. They will then do a carbohydrate analysis on the feed and the indigestible feed residue in the rumen and feces to determine if carbohydrate digestion differs among high and low efficiency animals.


This project will help to better understand why some animals are better at digesting forage based diets than others. It will also examine whether the fiber digestion efficiency ranking of an animal changes when the feed composition is altered. A better understanding of digestibility will help in the development of tools to help select animals that are more efficient on pasture.