Oat Hulls as a Feed Source for Livestock

Overview
Oat hulls are commonly incorporated into cattle diets as a fibre source. Typical nutrient values include:
  • Crude protein: 2–4%
  • ADF: 40–50%
  • NDF: 80–90%
Research from the University of Saskatchewan demonstrates that significant differences exist in ruminal fibre degradability among oat varieties, largely due to variation in cell wall components—particularly acid detergent lignin (ADL).
 
Background
Oat hulls, a major by‑product of the milling industry, represent up to 25% of the oat grain’s weight. Their high fibre content makes them well suited for ruminant diets, but feeding value is strongly influenced by lignin concentration, which limits ruminal digestibility.
A study evaluated hulls from 10 widely grown western Canadian oat varieties:
  • Calibre
  • Derby
  • Triple Crown
  • AC Assiniboia
  • AC Juniper
  • AC Medallion
  • AC Mustang
  • AC Preakness
  • CDC Boyer
  • CDC Pacer
Chemical composition was assessed for all varieties. In situ rumen degradability was measured on hulls from AC Assiniboia and Calibre, along with Calibre straw.
 
Key Findings
1. Large Variation in Lignin Levels
  • AC Assiniboia hulls: 1.3% ADL
  • Other nine varieties: 5.4–7.7% ADL
This indicates a substantial range in fibre composition among oat varieties.
2. Higher Ruminal Fibre Degradability in Low‑Lignin Varieties
  • AC Assiniboia hulls showed nearly double the ruminal fibre degradability of Calibre hulls.
  • Fibre degradability of AC Assiniboia hulls was comparable to Calibre straw, reflecting their low lignin content.
 
Implications for the Oat Milling and Livestock Sectors
For Feed Value
  • Low-lignin oat hulls provide greater rumen digestibility, improving their usefulness as a fibre ingredient in cattle diets.
  • This may enhance energy availability from a feedstuff often considered low in nutritive value.
For Oat Processors
  • Selecting or contracting low-lignin oat varieties (such as AC Assiniboia) can increase the economic value of oat hulls by producing a coproduct better suited for ruminant feeding markets.