practice problems - nutrition exam 3

Which of the following is a major contributor to developing the structure of the rumen in pre-ruminants?

VFAs

Which of the following feeds would result in longer rumination times and longer retention compared to the other others?

alfalfa hay

What process is inhibited in ruminants that leads to the development of bloat?

eructation

Which compartment of the ruminant stomach is responsible for absorption of VFAs and ammonia?

rumen

The atmospheric environment of the rumen is ______ which enables fermentation. In order to absorb the products of fermentation, the rumen includes structures that increase surface area called ______

anaerobic, papillae

The largest proportion of rumen microbes belong to which class?

bacteria

Protein entering the small intestine comes from what sources?

• feed protein unmodified in the rumen

• microbial protein produced in the rumen

Match the rumen bacteria with its substrate: Cellulytic, Amylolytic, Proteolytic, Intermediate acid utilizers

• cellulytic - cellulose

• amylolytic - starch

• proteolytic - proteins

• intermediate acid utilizers - succinate

Which of the following are the major VFAs produced in the rumen?

Butyrate, propionate, acetate

______ modify the rumen environment by ____ gram positive bacteria. The overall effect is greater efficiency of fermentation and results in ______ methane production

ionophores, inhibiting, reducing

What are the potential sources of NPN in the rumen?

• urea from the host

• RDP

• urea in feed

When nitrogen is recycled in the rumen, what is the ultimate product?

amino acids

What distinguishes RDP and RUP?

degradability

Both the Total Digestible Nutrients (TDN) and Net Energy System (NE) can be used for applied feeding of animals. What are some limitations of using the TDN system?

• New methods for fiber analysis have been developed

• As we have selected for more productive animals over the years feed intake has increased

• Feed quality is dynamic and changes over time

• Based on data from experiments that were conducted many decades ago

What are consequences of feeding phytate without phytase products?

• Increased chelation of ions by phytate

• Limited bioavailability of metal ions like zinc, calcium, and iron

• Excretion of phosphorus into the environment increases

Which of the following is not a possible purpose for including feed enzymes in rations?

eliminate all anti-nutritional components

Do ruminants need phytase supplementation to enhance digestibility of phosphorus and other minerals?

No, some rumen microbes have phytase activity making exogenous phytase supplementation unnecessary

In animals, ______ diets require less digestive capacity in the gastrointestinal tract. Whereas ________ diets (containing things such as more plant material/fiber) require more digestive capacity and complexity in the gastrointestinal tract. 

more digestible, less digestible

Carbohydrates that escape digestion in the small intestine of simple stomached animals enter the ______________ for fermentation

large intestine

Match the hormone to its role in gluconeogenesis: insulin, glucagon, cortisol

• insulin - strongly inhibits gluconeogenesis

• glucagon - promotes gluconeogenesis

• cortisol - stimulates gluconeogenesis

what makes up a ruminant stomach?

rumen, omasum, reticulum, abomasum

what are the four steps of rumination?

regurgitation, remastication, reensalivation, reswallowing

what does fermentation always follow?

hydrolysis

what is the summation of methane?

hexose → 2 acetate + CO₂ + CH₄

what is the summation of acetate from CO₂?

hexose → 3 acetate

rumen modifying compounds _____ fermentation products to support _____ efficiency

improves, greater

what are the four important irreversible enzyme steps?

• pyruvate carboxylase

• phosphoenolypyruvate carboxykinase

• fructose-1,6-bisphosphate

• glucose-6-phosphatase