3 ways digestibility & intake are inversely related
1. increased intake = increase rate of passage
2. fiber digestion = dec. in concentrate diets
3. soluble CHO digestion = dec.in whole grains
How does digestibility of feed impact rate of passage in upper GI?
dec digestibility = dec rate of passage
How does digestibility of feed impact rate of passage in lower GI?
inc digestibility = dec rate of passage
(GI has more to do, so process slows down)
3 reasons that increase digestibility in feedstuff
1. less digestible cell wall (fiber & lignin)
2. decreased rate of passage
3. inc rate of digestion
2 sources of carbohydrates fed
soluble CHO like starches
NDF (fiber sources)
90% of the glucose & fiber sources in the rumen are used for _________.
Microbial crude protein
With more soluble CHO in feed, VFA production increases. What happens to rumen pH?
decrease in pH
What VFA is produced more on a roughage diet? concentrate diet?
What should you feed if you want more milk fat? more milk yield?
milk fat: more roughage
milk yield: more concetrate
What happens to the starch that makes it to the sm. intestine? (only about 10% of ingested starch)
digested by pancreatic amylase into glucose
How much glucose is absorbed as glucose?
Where does the rest of the glucose come from?
metabolism of acetate or propionate
Propionate is main source
Where does metabolism of acetate occur?
acetate arrives in the mitochondria of adipocytes. it is converted to Acetyl Co-A and goes into the TCA cycle
Where does metabolism of propionate occur?
Most propionate removed by liver & converted to succinyl CoA. goes to TCA cycle
What is more energetically efficient: acetate or propionate?
Propionate is more energetically efficient because it nets more ATP molecules per mole than acetate
How does propionate compare to glucose directly absorbed from diet?
Propionate is 94% as efficient as glucose at generating ATP
it takes 2 moles of propionate to make mole of glucose
What is more important: unsaturated FA or saturated FA?
all FA are hydrogenated to saturated FA in the rumen
Where are lipids broken down? by what?
lipids enter the sm. intestine & are broken down by pancreatic lipase into monoglycerides
What helps the monoglyceride enter the sm. intestinal villus?
the bile from the gall bladder forms a micelle (which is polar) and draws the monoglyceride into the villus
After absorption, monoglycerides are converted to triglycerides & moved through lymph system. Where is there destination?