Animal Nutrition Exam 2

difference between an animal's actual weight gain and its predicted gain based on its DMI, body weight, maintenance, and fat cover

looks at the difference between ADG

cattle with higher values are more desirable

Residual average daily gain

How do we improve feed efficiency?

Reduce feed costs, increase nutrition, and improve genetics

What is the importance of a feed analysis?

to determine the chemical composition (or nutrient) of feed ingredients

What does proximate analysis measure? *KNOW*

dry matter, ash, crude protein, ether extract, crude fiber, nitrogen-free extract

DM% of concentrate feeds (corn/soybean meal)

90%

DM% of corn silages

30-35%

What are possible errors in dry matter feed analysis?

Any materials that volatilize at high temperatures are lost

some liquids oxidize when heated and therefore increase in weight

includes fats, fatty acid esters, and fat-soluble vitamins often called crude fat

removes fat

Ether extracts

inorganic residue remaining after all the organic nutrients have been burned off or oxidized completely in an oven at 600C for 2 hours

only mineral is left

ash

What is a problem with crude fiber tests?

acid and base solubilize some of the true fiber, so it underestimates the true fiber in the test material

How is nitrogen-free extract found?

by difference

= (%DM - (% EE + % CP + % ash + % CF))

What does Nitrogen-free extract represent?

the soluble carbohydrates

- starch and sugar

What does proximate analysis directly measure? **KNOW**

Dry Matter

Nitrogen

Fat

Ash

What does proximate analysis indirectly measure?

moisture, crude protein, crude fiber, and nitrogen free extract

What 2 components of a Proximate Analysis are carbohydrates?

Crude fiber and Nitrogen-free extract

Proximate analysis measures...

dry matter, ash, crude protein, ether extract, crude fiber, nitrogen free extract

What is the benefit of proximate analysis?

Inexpensive, industry standard, works well for single ingredients and mixed feeds, and gets the basic information

What is neutral detergent fiber?

Hemicellulose, cellulose, and lignin

- predictor of voluntary intake

- intake of gut fill

cellulose and lignin

Used as an indicator of forage digestibility

Acid detergent insoluble fiber

Forages with a low ADF value are ______________

higher in energy

ADF =

cellulose + lignin

Hemicellulose =

NDF - ADF

Total digestible nutrients is the sum of

digestible fiber, proteins, lipids, and carbohydrate components

- it is directly related to digestible energy

How is metabolic water produced?

when lipids, carbs, and amino acids are catabolized to CO2 and H2O

100g of fat contributes to how many grams of water?

110g

100g of carbohydrates contributes to how many grams of water?

60g

Why is water important for livestock? *KNOW*

1. It is a universal solvent that facilitates cellular biochemical reactions involving digestion, absorption, and transportation of nutrients

2. Helps in the excretion of waste products

3. Helps regulate body temperature

soluble components of the plant (starches and beta-glucans)

available for fermentation

Alpha 1-4 linkage

What are the functions of polysaccharides?

energy storage in plant cells, energy storage in animal cells, and structural support

mixed CHO, contains more than one (often 2-6) types of sugar

- hemicellulose

- pectin

Heteropolysaccharide

a 1,4 linkage only

linear polymer of glucose molecules

15-30% of total starch in most plants

soluble in water

homopolysaccharide

amylose

form of starch found in animal tissue

mix of a 1,4 and a 1,6 bond

soluble in water

stored in liver and muscle tissue

homopolysaccharide

glycogen

- most significant factor limiting availability of plant cell wall to herbivores and microbes

- give rigidity to plant cell walls

-increases plan maturity

- provides plant rigidity

- not a carbohydrate

lignin

breaks down a 1,4 linkage via hydrolysis

amylase binds five consecutive glucose residues at specific subsites and cleaves between the second and third subsite

doesn't cleave a 1,6 linkage

Pancreatic a-amylase

amylase cleaves amylose to

maltose and maltotriose

amylase cleaves amylopectin to

maltose, maltotriose, and branched a-limit dextrins

What is the name of the reaction that breaks 1 molecule of maltose into 2 molecules of glucose?

hydrolysis

What is the correct order of enzymatic digestion of starch in the small intestine?

amylase then brush border enzymes

In ruminants, how much starch flows to the abomasum and SI? Is starch digested in the abomasum?

No, digestion of starch in abomasum due to HCl, it depends on the diet that the animal is receiving

- there is more starch in high-concentrate diets then the rumen is able to digest

What are the limitation of using F:G to measure feed efficency?

It doesn't distinguish between growth and maintenance requirements

Has little value as a trait used to genetically improve feed efficiency

Why is F:G still used?

It is easier to measure in practical conditions

Gold standard of feed efficiency

calculated as the difference between an animals actual intake and it's expected intake for body weight and level of production

cattle with lower values are more efficient than cattle with higher values

independent of production, growth, and body size

Residual feed intake

measures the chemical composition of feed

does not measure how much of a nutrient is available to the animal

Proximate analysis

Why do we dry feed at 105C?

The boiling point of water is 100C, this way all of the water is taken out of the feed

Dry Matter

Dry weight/ fresh weight

The higher the DM, the ____________ the moisture

lower

Measures nitrogen

to convert nitrogen to protein multiply by 6.25

Crude Protein (Kjeldahl procedure)

What do you do to preform an ether extract?

Boil a dry sample in ether for 4 hours

Crude Fiber

cellulose, hemicellulose, and liginin

Is crude protein directly or indirectly measure?

Indirectly

What class of nutrient is missing from proximate analysis?

Vitamins

What type of NDF values are desired?

low

- high means there is a lot of lignin and cellulose

What type of ADF values are desired?

low

detect infrared light that measures the amount of energy required to vibrate chemical bonds between atoms within molecules

- different chemical bonds require different amounts of energy

- used to determine protein, moisture, starch, lipids, and ash

Near Infrared reflectance spectroscopy

What is the difference between wet chemistry and NIRS?

wet chemistry uses heat and chemicals and NIRS uses light reflections

Can cows eat snow to meet water requirements?

Mature beef cattle and sheep can rely solely on snow as a water source, but more productive animals, such as feedlot cattle and dairy animals, must have free access to drinking water.

one of the most likely toxicities in SD

Selenium toxicity

What is the structure of carbohydrates?

C atoms arranged in chains to which are attached H and O

What elements are apart of carbohydrates?

Carbon, hydrogen, and oxygen

most important sugar in nutrition

major end-product of CHO digestion for non-ruminants

primary form of sugar used for energy

Glucose

Cellulose *know*

B-D-glucose (up)

Insoluble components of the plant wall (cellulose)

- resistant to breakdown by enzymes

- microbes can digest cellulose

Beta- 1-4 linkage

glucose + galactose

- milk sugar

- critical component of milk replacers

Lactose

glucose + fructose + galactose

raffinose

How is hemicellulose different from cellulose?

hemi is heteropolysaccharides (different types) and is cellulose is only made up of one monosaccharides

special enzymes that are found on the microvilli of the small intestine that completes digestion

- they are not released in the lumen

brush border enzymes

Why is sucrase absent in ruminants?

sucrase is a simple form of sugar and as soon as it reaches the rumen the bacteria takes care of it - there is no need for it

Do we have enzymatic digestion in the large intestine?

No, only hindgut fermenters can

How much food does livestock eat that is inedible to human?

86%

What animals are the only species able to transform grass into food?

cattle and sheep

What % of the worlds land is not suitable for tillage?

67%

Is eating less meat really the solution?

No

How do you measure feed efficency?

lbs of feed/ lbs of gain, lbs of gain/lbs of feed, residual feed intake, and residual average daily gain

What is the most important nutrient for animals?

water

Do calves prefer warm or cold water?

warm

How do animals get water?

drinking water, water present in feed, and metabolic water

Where is water lost in animals?

urine, feces, sweat, saliva, milk, evaporation from the lungs through respiration

simple sugars that cannot be hydrolyzed into simpler compounds

- hexose and ribose

Monosaccharide

most important carbohydrate in animal feed

composed of many single monosaccharide units linked together

Polysaccharides

Most abundant CHO in nature

provides structural integrity to plant cells

B 1,4 linkage, straight chain, nonbranching

highly stable

- no enzymes can break it, only microbial cellulase

Cellulose

Is fiber digested in the small intestine? Why?

No, we do not have the enzymes to digest fiber

What is the factor used to calculate crude protein from nitrogen?

6.25

How does feed analysis for monogastrics and ruminants differ?

ruminant's feed needs to be tested for protein levels and monogastric's feed needs to be tested for amino acid levels

As the forages mature NDF.....

increases

How is neutral detergent fiber determined?

by boiling feed samples for an hour is a solution containing a pH of 7

- it extracts the soluble components of the feed and leaves the insoluble materials (NDF)

NDF =

cellulose + hemicellulose + Lignin

What is an indicator of voluntary intake?

NDF

- must be properly calculated

- are faster and cheaper than wet chemistry

NIRS instruments

Is water important for calves? Why?

Yes, it increases their feed intake which in turn increases their rumen development and it prevents diarrhea and dehydration

100g of protein contributes to how many grams of water?

42g

What are 3 factors that affect water requirements? *KNOW*

temperature, diet, physiological state, level of exercise, health

What happens when animals are not provided adequate amounts of water?

decreased feed intake, dehydration, less control of thermal regulation, and potential death

a build up leads to methemoglobin, a form of hemoglobin that lacks oxygen-carrying ability

Nitrate toxicity

PEM, blindness, ataxia, recumbancy, seizures

Sulfur toxicity

major components of plant material

hydrates of carbon formed by combining CO2 and H2O

serves as the structural component of plants

formed by photosynthesis in plants

Carbohydrates

What is the classification of CHOs?

Based on the number of carbon atoms and number of molecules of sugar

Which type of glycosidic bond can not be broken by mammalian animals?

beta

- pentose

- found in every living cell

ATP-> energy transfer

Riboflavin-> B-vitamin

RNA -> protein synthesis

DNA -> genetic coding

Ribose

glucose + fructose

- table sugar

- found in sugar cane and beets

sucrose

glucose + glucose (alpha 1-4 linkage)

- found in starch

Maltose