Food Animal Nutrition Flashcards
what are the 4 forestomach compartments and what are the functions of each?
rumen: fermentative vat of microbial digestion
reticulum: retention of coarse feed for more rumination and particle separation
abomasum: true stomach, acid secreting
omasum: sort feed and increase surface area to absorb water, VFAs, and electrolytes
how are the contents of the rumen stratified? (3)
upper layer is gases
middle layer is fiber/forage mat to maintain cudding and rumen health
lowest layer is grain and yesterday’s forage
what are the 4 different contraction patterns and what are the function of each?
- primary: mixing of feedstuffs (the rumen contractions felt on a physical exam); biphasic reticular contraction followed by contraction of rumen in dorsal and then ventral sac
- secondary: eructation (burping); contraction of cranial rumen pillar and pushing of rumen gas cap forward to cardia then out through esophagus
- rumination: cud chewing
- esophageal groove closing: during nursing, calves only
what nerve has the greatest impact on forestomach ability?
vagus nerve; parasympathetic; main driver of rumen contraction; primary stimulus for normal motor activity, is 90% sensory and 10% motor
what factors positively and negatively affect forestomach motility?
increase:
feeding, milking, low environmental temperature
decrease: general depression, sleep, anesthetics, satiety, pyrexia (fever), pain
what pair of salivary glands in ruminants produce the majority of saliva?
the parotid glands (L and R)
what is the chemical makeup and pH of saliva? how does this makeup influence its function?
high in Na, K, and HCO3-; means is very alkaline so can act as a buffer against rumen contents
what are the major end products of nutrient fermentation?
volatile fatty acids (VFAs):
acetate, proprionate, butyrate
what are the 3 primary VFAs produced and how does dietary makeup influence their ratios?
acetate: main produced in high forage diets
proprionate: main produced in high concentration diets
butyrate: stable at 10% of VFAs produced no matter the diet
which VFA is gluconeogenic? what is the fate of the other VFAs produced during fermentation?
proprionate; acetate and butyrate are converted to ketone bodies and oxidized for energy
what is the effect of effective fiber on rumen function? (4) how does a diet low in effective fiber impact digestion?
physically effective fiber is essential for proper rumen function for formation of the fiber mat, feed efficiency, rumen buffering via salivation and rumination, and rumen filling;
a diet low in effective fiber will see decreased rumination and buffering via saliva, decreased rumen mat formation, decreased feed retention time in rumen, and decreased fiber and feed digestion in the rumen
what are the 2 forms of dietary protein in ruminant rations and what do these terms mean?
- ruminally degradable protein (RDP)
- ruminally undegradable protein (RUP): escapes ruminal degradation
what happens to RDP following hydrolysis to peptides and AAs?
the peptides are incorporated into bacterial cells or deaminated to NH3, forming microbial crude protein that is digested post-ruminally (contains all 10 amino acids and allows ruminants to live for a short time with little to no dietary protein);
individual amino acids are fermented to branched chain VFA to feed the bacteria
what is the fate of ammonia that is generated during protein digestion in the rumen?
it provides a source of nitrogen for microbial protein synthesis
what are the products of fat metabolism in the rumen?
lipolysis yields glycerol and free fatty acids; the glycerol acts like proprionate and is fed to krebs cycle for gluconeogenesis and the free fatty acids are biohydrogenated to decrease toxic effect on microbes
