Daily Saliva Secretion in Adult Cow

Normal secretion of saliva per day by an adult cow is about-

Correct Answer: 150 Litres / day

An adult cow secretes approximately 150 litres of saliva per day — remarkably high compared to humans (1–1.5 litres/day), reflecting the critical physiological role of saliva in ruminant digestion.

Why Do Ruminants Need So Much Saliva?

• 1. Rumen buffering (most important): Alkaline saliva (pH ~8.0; rich in NaHCO₃ and Na₂HPO₄) neutralizes VFAs continuously produced by fermentation → maintains rumen pH 6.5–6.8
• 2. Lubrication: Lubricates dry feed for bolus formation, swallowing, and rumination
• 3. Rumen fluid supply: Major water source for ruminal contents
• 4. Urea recycling: Salivary urea → rumen → ammonia → microbial protein (Nitrogen recycling)
• 5. Anti-bloat: Mucin in saliva prevents frothy bloat by destabilizing foam

Key Salivary Facts

• Ruminant saliva: pH ~8.0, NO salivary amylase, alkaline (NaHCO₃ + Na₂HPO₄)
• Pig and human saliva: Contains salivary amylase (ptyalin) → starch digestion starts in mouth