Feedstuffs in Animal Nutrition

Question 1

What is AAFCO?

Answer 1

Association of American Feed Control Officials

Question 2

What is the most expensive part of running a farm?

Answer 2

65-75% of input costs deal with feeds. Processing feeds increases this input cost.

Question 3

What is a forage (roughage)?

Answer 3

A feed that contains more than 20% crude fiber and is less less than 70% TDN (total digestible nutrients)

Roughages account for around 54% of all feed for livestock in the U.S., especially for grazing animals

Question 4

What are concentrates? What two categories are there?

Answer 4

Concentrates are less than 20% fiber.

The two categories are energy concentrates and protein concentrates.

Question 5

What is a protein concentrate?

Answer 5

A concentrate with more than 20% crude protein (low fiber, high protein)

Question 6

What is an energy concentrate?

Answer 6

A concentrate with less than 20% crude protein (low fiber, low protein)

Question 7

What constitutes fats and oils?

Answer 7

They contain more than 50% lipids

Question 8

What constitutes minerals?

Answer 8

They are less than 20% organic material

Question 9

How do forages account for the majority of feed?

Answer 9

Pasture, rangeland (account for 36% of feed for livestock, grazing)

Harvested forages (account for 18% of feed for livestock)
- silage
- hay
- haylage

Question 10

What are some types of roughages?

Answer 10

1. Grasses
2. Legumes
3. Forbes (broad leaved plants like dandelions)
4. Browse
5. some byproducts

Question 11

Discuss grasses

Answer 11

Grasses are a roughage typically used for grazing or making hay.

Some grasses are annuals, and need to be planted seasonally. Others are perennial, and grow indefinitely.

Some grasses include the cool season (C3) grasses and warm season (C4) grasses.

Grasses have a wide range of nutrient availability affected by:
- age of the grass
- rain
- fertilizer
- soil
- region

Question 12

What are some physical characteristics of grasses?

Answer 12

long, narrow leaves

cylindrical stems with nodes or seeds

Question 13

What’s the difference between C3 and C4 grasses?

Answer 13

C3 grow in cool seasons and produce more water and less CO2

C4 grasses grow in warm seasons and produce more CO2 and less water

Question 14

Discuss legumes

Answer 14

Legumes are more upright than grasses because they tend to have more lignin, which provides rigidity.

Legumes often have woody stems and trifoliate leaves.

Legumes have more protein than grasses.

Question 15

Describe the relationship between rhizobia and legumes.

Answer 15

Rhizobia are a bacteria that convert N2 to NH4+ for the plant to use. This ammonium is why legumes contains more crude protein than grasses.

The plant supplies energy and other nutrients to the bacteria.

Question 16

Discuss the nutritive value of grasses compared to legumes.

Answer 16

Legumes have a greater amount of key nutrients, including calcium and protein. However, legumes also have a higher amount of lignin, which decreases digestibility.

Question 17

What factors affect the nutritive values of forages?

Answer 17

1. Maturity: quality declines as the plant matures because lignin concentration increases
2. Species and cultivars: some are selected for quality or yield
3. Leaf-stem ratio: leaves have more nutrient dense, non-structural carbs (mores leaves = better)
4. Harvest and storage method

These factors are more variable than grains/concentrates

Question 18

Discuss plant maturity and quality.

Answer 18

Different species and segments of the plant decline at different rates as the plant matures.

Leaves remain digestible despite increasing age.

ex. Brown mid rib, a GMO corn, has lower lignin and improved digestibility at the cost of reduced structural integrity.

Question 19

Discuss how plant parts differ in nutritional quality.

Answer 19

Leaves have greater nutritional quality because they contain more non-structural carbs, more protein, and less structural carbs.

Stems are less nutritious because they are largely composed of vascular tissue and structural carbs.

Question 20

What relationship exists between quality, yield, and plant maturity?

Answer 20

As plant maturity increases, plant quality decreases, but yield increases.

Question 21

Discuss grains and list important energy concentrates.

Answer 21

Grains have greater nutrient availability than forages, and are still a popular feed for ruminants. They are also good for animals with simple stomachs that cannot handle variable forages.

Grains are often energy concentrates.

Some important energy concentrates are:
- corn
- barely
- sorgum
- wheat
- oats
- rye

Question 22

Why is corn “king?”

Answer 22

2/3 of the corn kernel is starch. This makes it a good source of energy as it is broken down in the small intestine.

Fiber is found in the corn bran.

Fat is in the corn germ.

Question 23

What are some origins of protein concentrates?

Answer 23

1. Plants (ex. soybeans)
2. NPN (non-protein nitrogen)
3. animal (meals)

Question 24

Why is protein and N recycling important to ruminants?

Answer 24

Ruminants can recycle N and the microbial population can use it to make proteins in the rumen, which can be digested in the small intestine.

Question 25

What are some examples of protein concentrates?

Answer 25

soybeans, canola seeds, flax, sunflowers, cottonseed

Question 26

What are oilseeds?

Answer 26

Seeds that are high in fat and protein, like soybeans, canola seeds, etc

Question 27

What is gosypol?

Answer 27

Gosypol is a phenolic chemical present in cottonseed. It binds to the amino acid lysine and reduces its biological availability for the animal. Ruminants are more tolerant than non-ruminants. Issues that gosypol can cause include: - green egg yolks due to interaction with Fe - liver lesions - cardiac failure, pulmonary edema, and labored breathing (thump piglets) - decreased reproduction The issues associated with gosypol is mostly due to raw cottonseeds, therefore, processing is important.

Question 28

What are some byproduct proteins?

Answer 28

millfeeds plant or animal byproducts

Question 29

What is the maillard reaction?

Answer 29

In the presence of heat and water, the carboxyl group of a sugar is bound to the free amino end of lysine, making it into a less digestible compound. If the heat is not excessive, this bond is broken in the acidic conditions of the abomasum, and the amino acids are available in the small intestine. (bypass protein) If the heat is excessive, and artificial, indigestible polymer is formed. (heat damaged protein)

Question 30

What are some general characteristics of plant byproducts?

Answer 30

Low starch content high fiber high fat (traditionally, not so much anymore) Generally, the starch and fats are used for human purposes, leaving behind a low starch high fiber byproduct. Most mill feeds are used on cattle of hindgut fermenters that have the ability to handle the high fiber thanks to their microbial populations.

Question 31

What two processes are used to process corn?

Answer 31

wet milling and dry milling

Question 32

What does wet milling produce?

Answer 32

Wet milling is used to make corn starch, corn bran, corn syrup and corn oils. Wet milling is for human food application. The byproducts produced for animal use include corn gluten meal and corn gluten feed. Corn gluten meal is often used as poultry feed, and the highly fibrous corn gluten feed is often included in cattle rations.

Question 33

What does the dry milling process produce?

Answer 33

This process is used to make ethanol. The byproducts produced that are used in animal feeds include wet distiller's grains and dried distiller's grains.

Question 34

What are some general characteristics of animal byproducts?

Answer 34

ex. meals low starch content high protein that is also high in quality variability

Question 35

What are some rules and regulations surrounding the use of animal proteins in feeds, and why do they exist?

Answer 35

Animals over 30 months of age are not allowed to be slaughtered for use of their proteins in feeds. No "high risk" protein byproducts are allowed to be used for cows, humans, or pets. Ruminant byproducts cannot be fed to other ruminants. The reason for these regulations is that on December 23, 2002, mad cow disease (bovine spongiform encephalopathy) was detected in the U.S. Since BSE does not manifest in younger cattle, this is why the 30 month rule is in place

Question 36

Describe the energy qualities of fats and oils

Answer 36

Fats contain 2.25 times the energy of carbs, and are more energy dense. They work well as pellet binders.

Question 37

Why should fats and oils not be overfed?

Answer 37

In ruminants, high concentrations of unsaturated fats are toxic to the microbes and reduce fiber digestibility. In swine, they deposit the type of fat they're fed. Too much fat can lead to poor quality cuts.

Question 38

What is rumen protected fat?

Answer 38

Ex. Megalac Fatty acids bound with calcium, which prevents the microbes from recognizing the fat. Therefore, this fat is not biohydrogenated, and is allowed to pass to the small intestine for digestion without being altered.

Question 39

Define drugs

Answer 39

Substances intended for use in the diagnosis, care, mitigation, or treatment or prevention of disease; or substances, other than food, intended to affect the structure or function of the body drugs require FDA approval

Question 40

What are non-nutritive feed additives?

Answer 40

any compound added to the diet for reasons other than to supply nutrients

Question 41

Describe the Food, Drug, and Cosmetic Act

Answer 41

For animal drugs to be used in the U.S., they must be... 1. proven safe and effective (for the target animal and when used as labeled) 2. food must be safe for human consumption 3. FDA is responsible for enforcement (delegated to the Center of Veterinary Medicine)

Question 42

What are some non-regulated feed additives?

Answer 42

flavors buffers probiotics and prebiotics intake regulators yeast- "armaferm" fungal products - "vitaferm" anti-oxidants enzymes

Question 43

What is GRAS?

Answer 43

GRAS = Generally Recognized As Safe Too add a chemical to this list, it must be ... - submitted to the FDA - have a compilation of available information on utility and safety that is normally published in literature For use in a new product, efficacy must still be proven

Question 44

What are some regulated feed additives?

Answer 44

antibiotics ionophores anthelmintics hormones beta-antagonists coccidiostats

Question 45

Describe antibiotics

Answer 45

- "against life" or "destructive to life" - bacteriostatic prevents the growth of bacterial - bactericidal kills bacterial Modes of action: - control sub-clinical disease - nutrient sparing effect - metabolic effect - more ATP

Question 46

What are some issues associated with feeding antibiotics?

Answer 46

They can be used as growth promotants Antibiotic resistance can develop and be transferred to people We are no longer able to give antibiotics to animals without a veterinary prescription

Question 47

What is the veterinary feed directive?

Answer 47

States that no antibiotics used for humans, can be fed with a "growth promotant" claim Antibiotics can still be used to prevent and treat diseases with veterinary prescription

Question 48

What are anthelmintics?

Answer 48

Dewormers that can easily be delivered by feed Commonly used in swine and poultry diets Ex. Dichlorvos, Levamisole, Ivermectin

Question 49

Describe buffers

Answer 49

Buffers are non-regulated feed additives that can be added to the diet to reduce the acid load placed on the rumen when high levels of grain are fed or when hay and grain are fed separately. Often used in lactating dairy cows or feedlot cattle during diet adjustments. examples: Sodium Bicarbonate Remember, the rumen pH is generally happy around 6

Question 50

How are organic acids used in feeds?

Answer 50

They are used to lower stomach pH and improve protein digestion, which helps reduce incidence of pathogens. Ex. citric cid in used in piglet and chick feeds. In cattle, weak bases are used to raise rumen pH

Question 51

Describe how enzymes are used in feeds.

Answer 51

Enzymes are non-regulated feed additives. A common one is phytase, and it is used to release phosphorous to increase its absorption in the body while reducing its excretion. Enzymes also help increase the digestibility of non-starch polysaccharides. ex. avizyme contains xylanase, protease, and amylase

Question 52

Describe feed flavors

Answer 52

Flavors are a non-regulated feed additive They are added to: - improve uniformity of taste - mask foul odors - improve palatability of objectionable ingredients - attract animals - help market the diet

Question 53

What are some eating behaviors associated with flavor?

Answer 53

Aversion: flavors associated with discomfort will be avoided ex. ewes teach their lambs to avoid certain plants that can be toxic Imprinting: flavors associated with desirable sources of nutrition will be sought ex. sows and piglets fed the same diet have better gain and intake

Question 54

Describe direct fed microbials

Answer 54

non-regulated additives Probiotics: microbes themselves Prebiotics: food for microbes Yeast and other fermentation products are also examples

Question 55

Describe ionophores

Answer 55

Ionophores are a bacteriostatic antibiotic that allow ions to move through the membranes of gram-positive bacteria. This slows the growth of Streptococcus bovis They are a regulated feed additive. Ionophores increase propionate and decrease acetate in the rumen. Propionate is more efficient for rumen fermentation purposes, as acetate promotes carbon loss Horses are sensitive to ionophores because they absorb them too well, leading to toxicity

Question 56

What is the relationship between ionophores and metabolism?

Answer 56

Ionophores increases feed efficiency.

Question 57

Describe growth-promotants like beta-antagonists

Answer 57

They shift energy partitioning from fat to lean tissue They are not an antibiotic or a hormone, and they have no withdrawal time before a harvest

Question 58

What are the benefits of paylean in pigs? Optaflexx in feedlot cattle?

Answer 58

Paylean is a growth promotant. Using it requires an increase in dietary crude protein. It increases carcass weight, feed efficiency, and daily gain. Optaflexx increased carcass weight and feed efficiency.

Question 59

Describe immunocastration of boars.

Answer 59

Boar taint is an adverse flavor caused by androstenone and skatole in pork. Vaccinations can promote antibodies against gonadotropin-releasing hormone (GnRH). This causes the boars to continue to grow rapidly, but not have boar taint or a need for physical castration.

Question 60

Describe hormones.

Answer 60

They are a regulated feed additive. There are 24 FDA approved proteins, based on estrogen, androgens, or progestins. ex. Melengesterol acetate (MGA) - synthetic progestin - prevents estrus behavior - improves gain and feed efficiency - no withdrawal period - only fed hormone Most hormones are implantable, and are often used in beef cattle.