Biochemical consequences of (protein and energy) imbalance (ruminants)

Question 1

What is metabolism focused on in pigs and carnivores?

Answer 1

Pig - glucose and LCFA

Carnivore - amino acides

Question 2

What are the 2 routes of amino acid metabolism in pig liver?

Answer 2

Converted into either pyruvate (glucogenic) or acetyl CoA (ketogenic)

Question 3

What is the dual blood supply of the liver?

Answer 3

Blood from hepatic artery (from coeliac artery) and the HPV.

Question 4

In pigs, where do LCFAs from the gut go in the fed state? 5

Answer 4

MAJOR ROUTE: Primarily become amino acids, go to other tissues (fuel), adipocyte (–> fatty acid) or muscle (–>acetyl CoA),

MINOR ROUTE: to liver (–> acetyl CoA)

Question 5

What are the main metabolic pathways in the fasting omnivore?

Answer 5

LCFA –> muscle (acetyl coA), other tissues (fuel), liver (acetyl coa)

Muscle –> amino acids –> liver (pyruvate or acetyl coA depending on what is needed)

Question 6

What are the major pathways during perceived starvation/diabetes?

Answer 6

Adipocyte –> LCFA

LCFA –> liver (acetyl coA) [also to muscle (acetyl coA), other tissues (fuel)]

Acetyl coA (liver) –> ketone bodies

Question 7

Why do ketone bodies form?

Answer 7

beta oxidation happens so quickly that so much ATP is produced that the CAC is switched off therefore the only thing you can make with acetyl coA (liver) are ketone bodies (part of fasting response). This decreases the brain’s need for glucose as ketone bodies can be used instead. However RBCs are obligate glucose users.

Question 8

What are the major pathways in a steady state ruminant?

Answer 8

VFA (from GIT) –> liver (acetyl coA)
Glucose 6-P (liver) –> glucose
Glucose –> other tissues (fuel)

Question 9

What are the major metabolic pathways in a ruminant during a period of high demand?

Answer 9

Fatty acid (adipocyte) –> LCFA –> liver –> acetyl co A –> ketone bodies

GIT –> VFA

Question 10

Why is soya bean fed to ruminants?

Answer 10

it is a bypass protein if heat treated so not fermented to VFAs in rumen. Instead it is digested in the abomasum and SI.

Question 11

Where do cows get glucose from?

Answer 11

absorb very little so need to make it from propionate via an intermediate in the CAC, Thus you can change ruminant diet to increase amount of glucose they produce

Question 12

What are the VFAs?

Answer 12

Acetate (2 carbon)
Propionate (3C, important because it has an uneven number of carbons therefore unusual route of metabolism which is useful)
Butyrate (4C. broken down in last step of beta-oxidation to 2 acetyl coA)