• Frothy Bloat (Primary Ruminal Tympany):
• Occurs when cattle graze succulent, immature legume pastures (alfalfa, white clover) rich in soluble leaf proteins (18S chloroplastic proteins, saponins).
• During rapid microbial fermentation in the rumen:
• Soluble proteins and bacterial mucopolysaccharides act as foaming agents, trapping fermentation gases ($CO_2$ and $CH_4$) inside fine, persistent liquid bubbles.
• This creates a stable, tenacious foam throughout the ruminal digesta.
• The foam covers the cardia, inhibiting the eructation reflex and preventing free gas clearance, leading to life-threatening ruminal distension.
• nalysis:
• (Formation of a stable foam in the rumen): Correct primary cause.

Correct option: (2) Formation of a stable foam in the rumen