quiz #1: digestion

about how much of production costs is feed?

60-75%

who’s feed costs the most out of livestock animals?

1. swine (60-80%)

2. finisher cattle (70%)

3. broilers/turkeys (65%)

4. dairy/cow calf (50-60%)

5. poultry (55%)

6. feeder lambs (50%)

how much fructose is in corn?

not a large amount (<1%)

we get fructose from converting corn starch to fructuose

what is nutrition?

a function of living plants and animals consisting of the taking in and metabolism of food material whereby tissue is built up and energy is liberated

what is metabolism?

the sum of the chemical and physical changes occuring in tissue, consisting of anabolism and catabolism

what is anabolism?

the building up in the body of complex chemical compounds from simpler compounds, usually with the use of energy

what is catabolism?

the breaking down in the body of complex chemical compounds into simpler ones, often accompanied by the release of energy

what is homeostasis?

the state of equilibrium in the body with respect to various functions and to the chemical compositions of the fluids and tissues

what is a nutrient?

any chemical (element or compound) in the diet/ration/feed that supports normal reproduction, growth, lactation, or maintenance of life processes

energy values of feedstuffs are difference for various species primarily due to the animals ability to utilize __

fiber

what are the 2 types of nutrients?

essential nutrients and non-essential nutrients

what is an essential nutrient?

can NOT be made at all or in great enough quantities in the body and it (or a derivative) must have a critical biological function

ex: lysine, calcium, vitamin E

what are the classes of essential nutrients? (5)

1. water

2. amino acids

3. essential fatty acids

4. energy

5. minerals

what is a non-essential nutrient?

can be made in the body and is not needed in the diet - function is for flavor

ex: alanine, glucose (carbs), vitamin C (in most species)

what are the 10 essential amino acids?

PVT TIM HALL

• Phenylalanine

• Valine

• Threonine

• Tryptophan

• Isoleucine

• Methionine

• Histidine

• Arginine

• Leucine

• Lysine

what nutrients do humans need but not ruminants?

vitamin C, possibly fiber

what is the water composition of plants vs animals?

plants - 70%

animals - 54%

animals store energy as _, but plants store energy as _

fat ; carbohydrates

what are the essential macrominerals?

Ca, Cl, Mg, P, K, Na, S

what are the essential microminerals?

Cu, I, Fe, Mn, Se, Zn

what are the fat soluble minerals?

A, D, E, K

on a dry matter basis, how much of plants is carbohydrates (CHO)?

75%

what is the carbohydrate composition of plants vs animals?

plants - 25%

animals - <1%

what is the lipid composition of plants vs animals?

plants - <1%

animals - 26%

what are sugars, starches, and fiber?

carbohydrates (CHO)

how much of animals is carbohydrates (CHO)?

essentially none

how does animal composition vary with age?

lipid content is low at birth

what is an autotroph?

an organism that produces organic compounds from carbon dioxide as a carbon source, using either light or reaction of inorganic chemical compounds, as a source of energy

ex: plants

what is a heterotroph?

an organism that requires organic substrates to get its carbon for growth and development

ex: animals

how do heterotrophs and autotrophs relate?

both depend on one another and can’t function without each other

are energy values and other chemical components dependent on the species?

energy values are a biological value and vary between species but all other values are a chemical determination that is independent of species

energy is determined by how an animal digests fiber, which differs greatly between species

alfalfa meal has the most energy in _ and the least in _

horses ; swine

are labels on food completely accurate?

no, they give us a good idea but are not entirely accurate

how to find the proximate calorie count?

[fat x9] + [carbs x4] + [protein x4]

what are 3 components of animal feed labels?

1. guaranteed analysis (based on proximate analysis)

2. ingredient list (in order of abundance)

3. quality assurance (for pet food only)

what is nutrient analysis?

analysis of the chemical composition of a feed or feed ingredient

the most common is proximate analysis

what is proximate analysis?

provides an approximation of the chemical composition of a feed

has a lot of gravimetric determinations

what are the components of proximate analysis? (6)

1. dry matter

2. ash

3. crude protein

4. ether extract

5. crude fiber

6. nitrogen free extract

what is dry matter?

the moisture content of a sample

process includes weighing before and after being heated, and the different is equal to the moisture loss

what temperature is dry matter typically heated at?

100-105 °C

what are factors that can affect dry matter?

1. time and temperature can afffect the results

2. volatile compounds other than water can be lost (VFA) when at temperatures less than 100°

what is crude protein?

the nitrogen content of a sample to indicate protein

what method is used to measure crude protein?

kjeldahl procedure

what is the kjeldahl procedure?

a process where a sample is digested in concentrated sulfuric acid, which converts all nitrogen to ammonium sulfate

the ammonium ion is then determined by titration with KOH

the analysis determines the N content, NOT the protein (N x 6.25 = CP)

what are some faults with the crude protein process?

1. it does not distinguish between types of nitrogen (it assumes all N is amino acids)

2. does not indicate the quality of the protein

3. can only run a limited number of samples per day

why is N multiplied by 6.25 in crude protein analysis?

the average protein content is 16% (16/100 = 6.25)

a different number is used based on the amino acid content in the food

is not an entirely accurate calculation

what was the 2007 pet food recall?

many cases of kidney failure as a result of contaminants in vegetable proteins imported into the US from china

caused by melamine, which is 66% N and toxic particularly to cats

what was the 2008 chinese milk scandal?

a food safety incident in china where melamine was added to milk to cause it to appear to have a higher protein content, resulting in kidney damage

what has recently replaced the kjeldahl procedure to measure crude protein?

the dumas method, which is a nitrogen analysis which is less expensive and has no acid waste since the method is based on combustion where the N gas given off is measured

what is ether extract?

measures the lipid content of the sample

extracts the lipid with ether using the soxhlet procedure using a gravimetric procedure and whats lost is the lipid content

what are some of the faults in ether extract?

1. does not distinguish between nutritive (triglycerides) and non-nutritive (waxes, etc.)

2. ether is highly flammable

3. ether can be anesthetic if there is bad ventilation

what is ash?

measures the total mineral content

heats at 600°C for 16 hours and uses a gravimetric method where the residue is the ash (burns everything else off)

what are some faults in measuring ash?

1. does not indicate the specific minerals in it (Ca, P, etc. - could be good or bad minerals)

2. a high value may indicate some kind of contamination of an ingredient with soil, limestone, or salt

what is crude fiber?

represent the structural carbohydrates - cellulose, hemicellulose, lignin

what is the process to extract crude fiber?

a process supposed to resemble digestion where fat free residue is boiled in a dilute base and then a dilute acid and dried

has largely replaced the van soest procedure

what is nitrogen free extract (NFE)?

represents the soluble or readily available carbohydrate fraction of the feedstuff

is a calculated value, not an extract (NFE = DM - CP - EE - CF - ash), whats remaining after everything

is mainly starch

what is the van soest procedure?

a process to replace crude fiber measurement (may show more than what the CF value says)

measures hemicellulose (NDF - ADF = hemicellulose)

what is neutral detergent fiber (NDF)?

boiling in sodium lauryl sulfate under neutral conditions to extract all of the cell contents to leave the cell wall (hemicellulose, cellulose, lignin)

what are the components of the cell wall?

hemicellulose, cellulose, lignin

what is acid detergent fiber (ADF)?

boiling in detergent (cetyl trimethylammonium bromise and sulfuric acid) to leave cellulose and lignin

crude fiber is most similar to ADF value

what is a calorie?

the amount of energy needed to raise the temperature of 1 mL of water 1°C

what other analytical procedure is used to measure energy?

bomb calorimeter

what other analytical procedure is used to measure amino acids?

amino acid analyzer

what other analytical procedure is used to measure minerals

atomic absorption spectrophotometer, inductive coupled plasma spectrophotometer

what other analytical procedure is used to measure fatty acids?

gas chromatography

what other analytical procedure is used to measure multiple feed components?

near infrared reflectance (NIR)

what does liquid chromatography measure?

amino acid analysis

what does gas chromatography measure?

fatty acid analysis (saturated, unsaturated, chain length)

what does HPLC measure?

amino acids, steroid hormones (drug residue analysis), vitamins

in a chromatography graph, how do you find concentration?

peak height is proportional to the concentration

the elution time is characteristic for particular amino acids

what does atomic absorption and ICP measure?

mineral profile

what are some considerations to have for analytical procedures? (4)

1. in feed mill vs commercial lab (speed vs accuracy)

2. cost

3. speed

4. simplicity

what 2 things are necessary for nutrient utilization?

1. digestion

2. absorption

what is digestion?

the preparation of food for absorption

what percent of food we eat is actually utilized?

80-85%

what are the 4 processes of digestion?

1. mechanical (chewing, muscle contractions)

2. chemical (stomach acid, bile)

3. enzymatic hydrolysis

4. microbial (fermentation)

what is fermentation?

the breakdown by bacteria under anaerobic conditions

what is the overall function of digestion?

to reduce food to a molecular size that allows absorption

what is absorption?

processes that result in the passage of small molecules from the lumen of the interstitial tract through the mucosal cells lining the lumen and into the blood or lymphatic system

what are the mechanisms for absorption (4)?

1. simple diffusion (water)

2. facilitated diffusion (amino acids)

3. active transport (glucose)

4. pinocytosis or endocytosis (immunoglobulins)

what 4 things determine the mechanism for absorption?

1. size

2. solubility

3. concentration

4. charge

what is simple diffusion?

no carrier required, moves down concentration gradient (high to low)

ex: water

what is facilitated diffusion?

a carrier protein helps to move down a concentration gradient (no energy expended)

ex: amino acids

what is active transport?

a carrier protein uses energy to transport molecules against a concentration gradient

ex: glucose

what molecule uses pinocytosis/endocytosis?

immunoglobulins

digestion + absorption = ?

digestibility

what 2 things determine the digestibility of a nutrient in a feed or an ingredient?

1. energy digestibility or availability

2. lysine digestibility or availability

where are mucosal cells found?

in the lumen

why might one look at the composition of feces?

to measure digestibility where everything that disappears has been digested and absorbed

what animals are considered carnivores?

cats and dogs

what animals are considered omnivores?

pig, human, chickens

what animals are considered herbivores?

horse, rodents, cattle, sheep

oligovore vs omnivore?

omnivore - generalist ; oligovore - specialist

what are the 2 types of hind gut fermentors?

1. cecal fermentors (rat, rabbit)

2. colonic digestors (horse, pig, human, dog, cat)

what are the 2 types of pregastric fermentors?

1. ruminants (cattle, sheep, deer)

2. nonruminants (colobine, monkey, hamster, kangaroo, hippo)