factors affecting digestibility
1) rate of passage
4) nutrient excess/deficiency
2 methods of digestion
takes place in true stomach/abomasum/gizzard.
acid hydrolysis and enzyme breakdown
evaluate animal performance fed graded levels of nutrient or ingredient
measure of amount of nutrients going in and those coming out
digestibility measures the amount of nutrients going in and those _____ _____
((weight feed X % nutrient in feed) - (weight feces X % nutrient in feces)) / (weight feed X% nutrient in feed)
sources of errors in digestibility trial
1) enzymes secreted into GI tract
2) nutrient of bacteria origin
3) nutrients from epithelium cells
4) feed waste and spillage
5) errors in proximate analysis
difference between intake and excretion.
doesn't take into account losses/gains from fermentation.
simple, fairly precise
difference between intake and excetion but collected at end of small intestine
bypasses microbial fermentation
surgery, more precise
measures enzyme and sloughed cell contribution
identical to ileal digestibility but also takes into account nutrients from digestive enzymes and slough intestinal cells
most precise, requires nutrient free diet.
hormone responsible for stimulating nutrient uptake by cells
Acid secretion in poultry occurs in the ____