Protozoa

• Protozoa are larger than bacteria, accounting for 106/ml of rumen liquid
• Make up to 50% of the total microbial biomass
• Two types of protozoa:
  1. Entodiniomorphs – beneficial, they produce enzymes that help digest the fiber in forage and plant particles
  2. Holotrichs – undesirable, they engulf bacteria, as well as soluble sugars, reducing bacterial numbers and the microbial protein supply
• Present in a normal rumen in young calves from 3-6 weeks of age
• Easily killed by a low rumen pH and so are usually absent in animals fed a diet that promotes low pH
• Ruminants can function fine without protozoa; however, when present they perform better
• Will consume bacteria
• Will live from 8 to 36 hours
  

Bacteria

Rumen fungi