animal nutrition exam 2 (copy)

Which steer is more efficient?

steer A: FCR= 5:1

steer B: FCR= 7:1

steer A is more efficient because he needs less food to gain weight

Residual Feed Intake (RFI)

the difference between actual feed intake and expected feed intake

What does proximate analysis measure?

chemical composition of feed

What nutrients are directly measured in proximate analysis?

dry matter

nitrogen

ash (mineral)

fat (ether extract)

What nutrients are indirectly measured in proximate analysis?

moisture (water)

crude protein

crude fiber

nitrogen free extract (NFE)

Why is 6.25 conversion factor used to calculate crude protein?

most proteins contain 16% nitrogen

100 divided by 16 = 6.25

How to calculate DM and the indirectly measured nutrients?

% DM = dry weight divided fresh (as fed) weight times 100

100 - answer ^ = ___ % water

What are the two types of proximate analysis that estimate carbs?

nitrogen free extract (NFE)

crude fiber

What does NDF measure?

neutral detergent fiber

Structural components of the plant: hemicellulose, cellulose, lignin

What does ADF measure?

acid detergent fiber

Least digestible plant compnents: cellulose & lignin

What are NDF and ADF indicators of?

NDF- predictor of voluntary intake

ADF- indicator of forage digestibility

What are the main differences between wet chemistry and NIRS?

wet chemistry uses heat and chemicals 

NIRS uses light reflection

What is ones strength and one weakness of wet chemistry?

strength: accuracy and precision

weakness: time consuming

One strength and ones weakness of NIRS?

strength: fast and cheap 

weakness: properly calibrated 

Energy diagram from gross energy to net energy

gross energy (GE)

• fecal energy (FE)

digestible energy (DE)

• gaseous energy and urinary energy (GE) (UE)

metabolizable energy (ME)

• heat increment (HI)

net energy (NE)

What is digestible energy (DE)?

energy remaining in the diet after fecal energy is subtracted

digestible energy = gross energy - fecal energy 

What is metabolizable energy (ME)?

energy remaining after urinary loss and gaseous losses arising from the GI are subtracted from DE 

ME = DE - urinary energy - gaseous energy 

What is heat increment (HI)?

heat produced (energy lost) by eating, chewing, digesting, and absorbing nutrients

How do you define net energy (NE)?

the remainder of “useful” energy and can be used for maintenance and production

What are the two methods used to measure heat production and/or energy retention?

• indirect calorimetry: calculated from amount of oxygen consumed and amount of carbon dioxide produced (headboxes)

• comparative slaughter: feeding trial, difference between body energy content in initial baseline animals vs animals at the end of the trial 

What is TDN? How is it calculated?

total digestible nutrients, overestimates energy supply from high fiber feed ingredients compared to highly digestible low fiber

TDN = digestible crude protein + digestible crude fiber + digestible nitrogen free extract + (digestible ether extract times 2.25)

What are the 3 main functions of water?

universal solvent

regulate temperature

elimination/excretion

Do we need to provide water for baby calves? Why?

Yes. It increases feed intake, helps with rumen development & prevents diarrhea and dehydration

What are the primary sources of water (how do animals get water)?

drinking water

water present in feed

metabolic water

How do animals lose water?

urine 

feces

sweat

saliva

evaporation from lungs through respiration

milk in lactating animals

What factors influence the amount of water required by an animal?

temperature (humidity)

diet

physiological state

level of excercise

health 

What has the greatest water requirements (water intake)?

young vs mature animals - mature 

pregnant vs lactating - lactating (producing milk)

cow fed hay vs cow fed silage - hay (silage has water, hay is dry)

cow in high vs low temp - high (stay hydrated)

What happens in cases of moderate water restriction? Severe water restriction?

moderate: decreased feed intake

severe: dehydration, less control of thermal regulation (increase respiration rate, increase pulse rate, and increase rectal temp), death

Why is water quality important? Name two toxic substances in water

lower water quality = lower water intake, lower feed consumption and lower performance

toxic substances: nitrates and sulfur 

What elements (atoms) makeup carbohydrates?

Carbon (C) Hydrogen (H) Oxygen (O)

What are the three major functions of CHO?

source of energy

storage of energy

structural units

Why do we have little carbs in animal tissues?

carbs are stored in small amounts as glycogen and used to mostly generate energy, <1% stored. fats are primary energy reserve in animal tissues

Which CHO do we find in the cell content? And in the cell wall?

cell content: glucose, starch, glycogen

cell wall: cellulose

What is the most important (and most abundant) monosaccharide in animal nutriiton?

glucose

monsaccharides are bonded together by _____ in a reaction called _______ where we have the elimination of one molecule of ________.

glycocydic bonds

condensation

water

Give examples of two disaccharides

sucrase, lactose

What are the classes of polysaccharides?

Homopolysaccharides

Heteropolysaccharides

What are the main differences between homopolysaccarides and heteropolysaccharides?

homo: made up of one type of monosaccharide

hetero: made up of two or more types of monosaccharides

What are the two types of starch? What are the main differences between them?

amylose: linear, 15-30% starch in plants, only alpha 1-4 glycosidic bonds, soluble

amylopectin: branched, 70-85% starch in plants, a 1-4 and 1-6 bonds, insoluble 

What are the main similarities and differences between starch and cellulose?

similiarities: made up only by glucose, found in plants

starch: all animals can digest, alpha bonds, has branched

cellulose: no animal enzymes can break the bonds, but microbes can, most abundant CHO, beta bonds 

What are the main difference between starch, cellulose, and hemicellulose?

structure and bonds, function, digestibility

What is the major site of starch digestion in monogastrics? What type of digestion? What is the final end-product of starch digestion?

small intestine, enzymatic digestion, glucose

What are the sites of starch digestion in ruminants? What types of digestion? What are the final end-products of starch digestion?

rumen: Microbial Fermentation, VFA’s

Small Intestine: Enzymatic digestion, glucose

What is hydrolysis of carbs?

breaking down carbs into simple sugars using water and ezymes

Where is pancreatic amylase produced? Where is it released?

pancreas

small intestine (duodenum)

Amylase breaks down starch into______,_______, and ______.

maltase, maltotriose, and dextrins

Which brush border enzymes are involved in starch digestion?

maltase, isomaltase, and sucrase

Describe starch digestion in the small intestine

1. starch reached the small intestine

2. pancreatic amylase breaks down amylase to maltose and maltotriose; and breaks down amylopectin to maltose, maltotriose, and dextrins

3. brush border enzymes (maltase and isomaltase) will finish the digestion of the disaccharides and oligosaccharides by breaking them to glucose 

4. glucose is absorbed in the blood stream

Mention two brush border enzymes their substrates and final products of digestion

maltase: 

• substrate: maltose

• final product: glucose

lactase

• substrate: lactose

• final product: glucose and galactose

Do chickens have lactase? Why?

No. They do not produce or drink milk.

Why is lactase activity high in the first weeks of life and then it reduces over time?

newborn mammals rely on milk as their main food source which contains lactose. eventually milk is not their main food source so its a natural adaptation to food

What are the steps necessary for glucose absorption

• glucose enter the gut cells with help of sodium

• then glucose moves out of the gut cells into the blood

• involves active transport into cell and facilitated diffusion into the blood

What are the transporters involved in glucose absorption?

sodium glucose linked transporter 1 (SGLT1)

• brings glucose into the intestinal cells along with sodium

glucose transporter 2 (GLUT2)

• helps glucose move from the intestinal cells into the bloodstream