CELLULAR BIOLOGY - Ruminant Digestion and Metabolism Flashcards
List the three main carbohydrates found in the ruminant diet
Cellulose
Hemi-cellulose
Polysaccarides
List the three kinds of microbes found in the rumen?
Bacteria
Fungi
Protozoa
What are the two main classes of carbohydrate digesting bacteria found in the rumen?
Cellulocytic bacteria
Amylolytic bacteria
Which carbohydrates are digested by cellulocytic bacteria?
Cellulose
Hemi-cellulose
Which carbohydrates are digested by amylocytic bacteria?
Polysaccharides
Which type of carbohydrate digesting bacteria is predominately found in a ruminant fed a forage based diet?
Cellulocytic bacteria
Which type of carbohydrate digesting bacteria is predominately found in a ruminant fed a grain based diet?
Amylolytic bacteria
How does cellulolcytic bacteria digest carbohydrates?
Cellulolcytic bacteria produces cellulase which cleaves the cellulose and hemi-cellulose beta 1,4-glycosidic bonds to produce glucose
How does amylolcytic bacteria digest carbohydrates?
Amylolcytic bacteria produces amylase which cleaves the polysaccharide alpha 1,4-glycosidic bonds to produce glucose
Can glucose be absorbed by the rumen?
No, glucose cannot be absorbed by the rumen
How are volatile fatty acids produced?
Volatile fatty acids are produced from the anaerobic microbial fermentation of glucose in the rumen
What are the three main volatile fatty acids produced in the rumen?
Propionate
Acetate
Butyrate
How are volatile fatty acids absorbed from the rumen lumen into the bloodstream?
Volatile fatty acids are absorbed by the rumen papillae and into the bloodstream
Why is it essential there a continuous absorption of volatile fatty acids from the rumen into the bloodstream?
To prevent an excessive decrease in the rumen pH
How does the length of the luminal papillae differ depending on the ruminant diet?
Long papillae: high volatile fatty acid concentration
short papillae: nutritional deprivation, low volatile fatty acid concentration
What is the function of propionate?
Propionate enters gluconeogenesis in the liver and contributes to glucose production
What are the functions of acetate and butyrate?
Acetate and butyrate are converted to acetyl CoA which can be directed to the citric acid cycle for ATP production or fatty acid synthesis for storage
In which two tissue types do acetate and butyrate undergo fatty acid synthesis?
Adipose tissue
Mammary glands
Which of the volatile fatty acids can be converted into ketone bodies?
Butyrate can be converted into ketone bodies
Which volatile fatty acid is seen most predominately in ruminants fed forage based diets?
Acetate is seen predominately in ruminants fed forage based diets
Which volatile fatty acid is seen most predominately in ruminants fed grain based diets?
Propionate is seen predominately in ruminants fed grain based diets
How does increased acetate concentrations affect milk composition in ruminants?
Increased acetate concentrations lead to an increased butterfat percentage in the milk
How does increased propionate concentrations affect milk composition in ruminants?
Increased propionate concentrations lead to an increased protein percentage in the milk
Why is there less blood glucose fluctuation in ruminants compared to non-ruminants?
There are less blood glucose fluctuations as ruminants eat more continuously so microbial fermentation is continually producing volatile fatty acids to be used in continuous gluconeogenesis
What are the three main lipids found in the ruminant diet?
Triacyglycerols (TAGs)
Glycolipids
Phospholipids
Which enzyme breaks down triacyglyerols (TAGs) into fatty acids and glycerol in the ruminant?
Microbial lipase breaks down triacyglycerols (TAG) into fatty acids and glycerol
In the rumen, what happens to the glycerol released from the breakdown of triacylglycerols?
Glycerol undergoes microbial fermentation into propionate
In the rumen, what happens to the unsaturated fatty acids released from the breakdown of triacylglycerols?
Unsaturated fatty acids undergo biohydrogenation by the ruminal microbes to form saturated fatty acids
Why do fatty acids in the rumen undergo biohydrogenation?
Because too many unsaturated fatty acids can be toxic to the microbes in the rumen
What is the main site of saturated fatty acid absorption in the ruminant digestive system?
Small intestine is the main site of saturated fatty acid absorption
In which physiological state are ruminants most likely to experience ketosis and why?
Ruminants are most likely to suffer from ketosis during early lactation as the high energy demand causes intense gluconeogenesis which removes oxaloacetate from the citric acid cycle, preventing acetyl CoA from entering the citric acid cycle and instead being converted into ketone bodies in the liver
How can ruminants survive on a poor protein diet?
Because the ruminant can use microbial rumen content as a source of protein
