What are the references for major sources and fate of the following substances in ruminant digestion
1) Propionic, ethanoic and butanoic acid
2) Methane
3) Carbon dioxide
4) Ammonia
1) Propionic, ethanoic, and butanoic acid:
The major sources of propionic, ethanoic, and butanoic acid in ruminant digestion are the fermentation of dietary carbohydrates by ruminal microbes. These fatty acids are produced during the microbial fermentation of glucose and other sugars in the rumen. The main source of glucose in ruminants is from dietary starch and cellulose.
References:
- Kamra, D. N., Patra, A. K., & Chatterjee, P. N. (2009). Effect of feeding inhibitors of methanogenesis on rumen fermentation and microbial populations in buffalo. Animal Feed Science and Technology, 148(3-4), 292-305.
- Moharrery, A. (2004). Rumen metagenomics: Tools and challenges. Asian-Australasian Journal of Animal Sciences, 17(1), 145-152.
2) Methane:
Methane is primarily produced in ruminant digestion through a process called enteric fermentation. Methanogenic archaea, residing in the rumen of ruminant animals, produce methane as a byproduct of the fermentation of organic matter by other rumen microbes. These methanogens thrive in anaerobic conditions and utilize the hydrogen and carbon dioxide produced during fermentation to produce methane.
References:
- Johnson, K. A., & Johnson, D. E. (1995). Methane emissions from cattle. Journal of Animal Science, 73(8), 2483-2492.
- Morgavi, D. P., Forano, E., Martin, C., & Newbold, C. J. (2010). Microbial ecosystem and methanogenesis in ruminants. Animal, 4(7), 1024-1036.
3) Carbon dioxide:
Carbon dioxide is produced in ruminant digestion through several pathways. It is produced during the fermentation process in the rumen when microbes break down carbohydrates. Additionally, carbon dioxide is released as a byproduct of the animal's physiological processes, including respiration and the breakdown of glucose during cellular respiration.
References:
- Janssen, P. H. (2010). Influence of hydrogen on rumen methane formation and fermentation balances through microbial growth kinetics and fermentation thermodynamics. Animal Feed Science and Technology, 160(1-2), 1-22.
- Martin, S., & Sauvant, D. (2010). Modelling methane production in ruminal fermentation. In Modelling Nutrient Digestion and Utilisation in Farm Animals (pp. 184-206). CABI.
4) Ammonia:
Ammonia is produced in ruminant digestion through the deamination of amino acids and the breakdown of proteins. Rumen microbes break down ingested proteins into amino acids and then convert them to ammonia through microbial fermentation. The ammonia generated is used by rumen microbes as a nitrogen source for synthesizing microbial protein.
References:
- Russell, J. B., & Hespell, R. B. (1981). Microbial rumen fermentation. Journal of Dairy Science, 64(6), 1153-1169.
- Huuskonen, A., & Huhtanen, P. (1998). The relationship between dietary characteristics and ruminal ammonia concentration. Journal of Animal Science, 76(9), 2701-2711.