PASTURE BLOAT

Bloat is a form of severe indigestion marked by a collection of gas in
the rumen that the animal is unable to expel. Normal digestive
processes create gases consisting chiefly of carbon dioxide and
methane in the rumen.  Most of the gases are eliminated by belching.  
Gases that are trapped may form a foam or froth in the rumen which
further prevents their elimination.  Froth formation can be caused by
many factors resulting from interactions between the animal, rumen
microorganisms, and differences in plant biochemistry.  The main
causes of bloat are an inherited tendency for bloat, certain proteins in
forage (particularly in legumes), the coarseness of the roughage and
the type of rumen microbial population.  Pasture bloat usually occurs in
animals grazing wheat pasture, lush legumes (alfalfa, Ladino, red
clover) or fed green-chopped legumes.  To prevent pasture bloat in
cattle you should plant pastures so that no more than 50 percent of the
forage mixture is alfalfa or clover, fill cattle on dry roughage or grass
pastures before turning to legume pastures, provide grass hay or
graze in a rotation using grass pastures.

Visual signs of bloated cattle include distension of the left side of the
animal, discomfort as indicated by stomping of feet or kicking of belly,
labored breathing, frequent urination and defecation, and sudden
collapse.