Large volumes of gas are generated in the rumen on regular basis by microbial fermentation .
Bloat occurs when bulk of this gas is not eliminated from the rumen by eructation or belching which is usually the means.
The rumen and reticulum becomes abnormally distended or enlarged with gases derived from rumen fermentation.
Frothy bloat may result in animals on pasture containing high amounts of alfalfa or clover or similar legumes which are rapidly digested in the rumen producing large bubbles of gas.
Frothy bloat can also occur in animals fed high levels of grains and concentrate rations.
Frothy bloat occurs after rapid ingestion of high protein, highly digestible feed that results in formation of excess amounts of stable foam in the rumen.
Free gas bloat occurs when the animal is unable to eructate free gas in the rumen.
The condition maybe due to partial obstruction of the esophagus by foreign bodies or tumors.
Consequences of bloat
Distension of the rumen puts pressure on thoracic and abdominal organs reducing blood flow to such organs.
Also, pressure on the diaphragm interferes with lung function leading to death due to hypoxia ( tissues and organs deprived of adequate oxygen).
Clinical signs
Left side abdominal distension
Affected animal stops eating and shows signs of distress
Breathing difficulties (rapid breathing)
Reluctance to move and recumbency and death
Cattle with tetanus, rabies, oesophageal obstruction and ruminal acidosis may also develop bloat.
With rabies there is a behaviour issue, with oesophageal obstruction there is profuse salivation and with acidosis there is also dehydration and liquid brown faeces.
In tetanus, the animal appears stiff.

Bloat is usually a life-threatening situation in livestock. A veterinarian should be sought immediately.
Insertion of a rumen trochar through the left flank into rumen is sometimes done but is often followed by complications such as peritonitis.
In less severe cases, stomach tube could be passed down the oesophagus into the rumen to relieve it of free gas.
Antifoaming agents such as vegetable oils, paraffin, etc can be delivered directly into the rumen via stomach tube or by drenching in cases of frothy bloat.
A veterinarian may recommend rumenotomy if none of the above worked.
The best control is to maintain balance between hay and legume pastures. Usually it is better to feed hays before introducing the animals to pasture.
Another way is to incorporate antifoaming agents in their feed or small pasture to prevent bloat.
Grains given to feedlot animals should not be finely ground as this induces bloat. Ensure to include roughages such as straw or hay in feedlot rations
As much as possible, minimize competition during feeding
Cattle areas must be kept free of wastes such as plastic, string, rope and wire that may lodge somewhere in the tract and cause bloat through obstruction.