Discuss the major source and fate of the following substances in ruminat digestion.
Ammonia
Ammonia is an important substance in ruminant digestion. It is primarily formed as a byproduct of microbial fermentation in the rumen, which is the first compartment of the ruminant stomach.
The major source of ammonia in ruminant digestion is the breakdown of dietary proteins by rumen microorganisms. These microorganisms break down proteins into their constituent amino acids, and subsequently deaminate the amino acids to produce ammonia. This ammonia is then used by the rumen microorganisms as a nitrogen source for their own growth and metabolism.
The fate of ammonia in ruminant digestion can vary depending on the conditions in the rumen. Some of the ammonia may be incorporated into microbial proteins and utilized by the rumen microorganisms. These microbial proteins are then digested by the ruminant host and provide a significant source of dietary protein.
However, excessive ammonia production can occur when the balance between dietary protein and carbohydrate availability is disrupted. In such cases, the excess ammonia may accumulate in the rumen and be absorbed across the rumen wall into the bloodstream. Once in the bloodstream, ammonia can be transported to the liver where it is converted into urea through a process called ureagenesis. Urea is then recycled back to the rumen via saliva or excreted via urine.
In summary, the major source of ammonia in ruminant digestion is the microbial breakdown of dietary proteins, while its fate depends on the balance between dietary protein and carbohydrate availability. Proper protein-carbohydrate balance is essential to ensure efficient utilization of ammonia as a nitrogen source for microbial protein synthesis, while excessive ammonia production can result in its absorption into the bloodstream and subsequent conversion to urea.