1.2 Comparative Nutrition - Nutrient review

Question 1

Essential nutrient

Answer 1

• Nutrient cannot by synthesized by metabolism
• Must be provided in the diet

Question 2

Conditionally essential nutrient

Answer 2

• Nutrient can be synthesized from suitable precursor, but not enough during some physiological stages
• Semi-essential: nutrient can be synthesized, but only from an essential precursor in the diet

Question 3

Nonessential nutrient

Answer 3

Nutrient can be synthesized in sufficient quantities

Question 4

6 categories of nutrients

Answer 4

1. water
2. aa (protein)
3. cho
4. fats and oils
5. minerals
6. vitamins

Question 5

What is quantitatively the most important nutrient?

Answer 5

Water

Question 6

What can water be a source of?

Answer 6

Nutrients
- Na, Ca, trace minerals, others

Question 7

How are water requirements described?

Answer 7

“Sufficient quantities of water of adequate quality”

Question 8

What are 2 reasons why water can be a major source of problems?

Answer 8

1. Microbiological contamination
   - Biofilms
   - Groundwater contamination
2. Chemical contamination
   - Nutrients - Na, Ca, phosphates etc. in high quantity
   - Toxic compounds
   - pH
   - Oxidation/reduction potential

Question 9

How much water do chickens normally consume? What do requirements depend on?

Answer 9

• Water normally ~2x feed intake
• Req depends on: environment (temp and humidity), health, stress
  *water intake decrease usually precedes feed intake decrease in sickness

Question 10

What does water consumption of a pig depend on?

Answer 10

1. Body weight and feed intake
2. Physiological stage

Question 11

What are the 4 conditionally essential AA?

Answer 11

1. Arginine
   - essential for piglets and birds
2. Histidine
   - essential for pregnant sows
3. Proline
   - may be essential for piglets and for chickens fed purified diets
4. Glutamate
   - may be limiting for weanling pig, chick growth

Question 12

What are the 2 semi-essential AA?

Answer 12

1. Tyrosine
   - can be supplied from excess Phe
2. Cysteine
   - can be supplied from excess Met

Question 13

Do animals have a protein requirement?

Answer 13

NO! They require essential AA
- Diet must also contain sufficient amino nitrogen to allow synthesis of non-essential AA by the animal; this is why we consider crude protein level when formulating diets
- Commercial nutritionists have moved away from the concept of formulating to a protein “requirement”

Question 14

Nutritional valuation of CHOs for pigs and chickens

Answer 14

1. Consider starch and fibre separately
   - Starch (generally) more available than fibre to monogastrics
2. Understanding is more advanced for pigs than in chickens
   - greater hindgut fermentation in pigs
3. Starch and fibre influence gut health
   - microbiome
   - microbially-synthesized nutrients
4. Enzymatic digestion
   - starch and sugars (lactose, sucrose, maltose)
   - not all starch is digested (resistant starch) and can behave like fibre (hindgut fermentation)
5. Not enzymatically digested but fermented:
   - Non-starch polysaccharides
   - Cellulose, hemicellulose, pectin, fructans
   - Oligosaccharides

Question 15

What CHOs get fermented?

Answer 15

Fibre and resistant starch
- Yields VFA (acetate, propionate, butyrate) absorbed in the hindgut and metabolized for energy
- Energy loss during fermentation (pigs)
- Energy utilization of VFA (pigs is 15% lower than ME from glucose

Question 16

What are non-starch polysaccharides?

Answer 16

Technically, any polysaccharide that is not starch
- cellulose hemicellulose, pectins, xylans, glucans
- In common usage, “NSP” is usually in the context of SOLUBLE non-starch polysaccharides, typically: arabinoxylans and beta-glucans

Question 17

What do soluble NSP do?

Answer 17

Increase digesta viscosity
- Reduce mixing of digesta = reduced expose to enzymes = reduced movement of nutrients to absorptive surfaces
- Create a more anaerobic environment = microbial proliferation = many pathogens are anaerobes = immune activation

Question 18

How are soluble NSP dealt with?

Answer 18

NSP-degrading enzymes
- major effect in decreasing viscosity
- minor effect is the release of sugar molecules for absorption

Question 19

Utilization of NSP

Answer 19

Energy utilization 0-79% in pigs
- fermentability differs among types of NSP
- affected by feeding level, physiological stage
- lower in poultry

Does not include effects of NSP on digestibility of other nutrients

Feed (exogenous) enzymes can increase utilization
- xylanase to digest arabinoxylans
- B-glucanase to digest B-glucans

Question 20

What are 2 essential fatty acids? What is a conditionally essential fatty acid?

Answer 20

Linoleic acid and Linolenic acid

Arachidonic acid - derived from linoleic acid

Question 21

7 macrominerals and 8 trace minerals

Answer 21

Macrominerals
- Ca, P, Na, K, Cl, Mg, and S

Trace minerals
- Fe, Zn, Mn, Cu, Co, Cr, I, and Se

Question 22

Macro-mineral supply

Answer 22

In grain-based diets
- Ca, Na, Cl: insufficient amounts; addition to diet as limestone
- Phosphorus: problem is it is stored in phytate leading to inadequate available (or digestible) P; addition of mono/di-calcium phosphate, rock phosphate, bone meal or phytase
- K, Mg, S: sufficient contents

Question 23

What 4 things can phytic acid bind and thereby, reduce the availability of?

Answer 23

1. Phosphorus
2. Protein
3. Starch
4. Divalent cations
   - Ca, Mg, Zn, Cu, Fe

Question 24

Phytase

Answer 24

Breaks down phytate molecule
- present to some degree in plants
- endogenous phytase (made by the animal) is low; higher in chicken intestine than pig intestine
- exogenous phytase (added to feed) is produced by microorganisms (yeast and bacteria)
- increased digestibility of minerals: P, Ca, Zn, Na, etc.
- increased digestibility of AA, starch and energy

Question 25

What are good sources for Fe, Mn, Cu, Zn (trace minerals)?

Answer 25

- sulfates, chlorides - chelated ("organic"): complex with AA or protein; increased availability bc it is protected from binding by phytate

Question 26

What are poor availability sources for trace minerals?

Answer 26

Oxides and carbones

Question 27

How is Se (trace mineral) added to a diet?

Answer 27

Na-selenate, Na-selenite, organic selenium

Question 28

How are trace minerals usually added to a diet?

Answer 28

Provided in a premix

Question 29

How are fat-soluble vitamins included in a diet since they are usually low in grain-based diets?

Answer 29

Provided in premix at ~10x requirement or more - Vit A and carotenoids - Vit D is added as: feed-grade D3 or vit D metabolites (25-OH vit D3 most important) - Vit E: a-tocopheryl acetate (synthetic) - Vit K: included in premixes as menadione (synthetic)

Question 30

Why is vit C not required by pigs or poultry?

Answer 30

Unlike humans, they can synthesize their own

Question 31

Water-soluble vitamins

Answer 31

- biotin - choline - folate - niacin - pantothenic acid - riboflavin - thiamin - pyridoxine - cobalamin

Question 32

How are water-soluble vitamins included in a diet?

Answer 32

1. provided in premix - different mixes for growing pigs and sows - different mixes for layers, broilers, breeders, turkeys 2. choline, thiamin, B6 in grain-based diets - sufficient for growing pigs, but not sows - usually supplemented for poultry 3. Other water-soluble vitamins - marginal contents for growing pigs, inadequate contents for sows, supplemented - supplements in poultry

Question 33

5 important notes about energy

Answer 33

1. A property, not a nutrient 2. Derived from nutrients: - protein, lipids, CHOs - VFA (from hindgut digestion) 3. Energy yield differs btw nutrients 4. No energy from minerals or water 5. Most expensive feed component - proportional increase in energy costs more than a similar proportional increase in any other nutrient

Question 34

Limiting nutrient is a concept that relates...

Answer 34

Performance to nutrient supply - asking if the diet has enough of a particular nutrient to support the desired performance

Question 35

First limiting nutrient

Answer 35

Nutrient present at the lowest amount relative to the requirement - amount of this nutrient will determine the level of production, regardless of other nutrients that might be deficient - can apply to any req nutrient; most commonly individual AA

Question 36

First limiting vs second limiting nutrient

Answer 36

First limiting - most deficient relative to requirement Second limiting - still deficient relative to requirement - not relevant until the first limiting nutrient has been addressed

Question 37

Commonly limiting nutrients

Answer 37

1. AA - Lys usually 1st limiting for pigs - Met usually 1sst limiting for chickens - Possibly limiting: threonine, tryptophan 2. Energy (limit to intake) - For chickens, pigs with high growth potential 3. Vitamins and minerals - Supplemented to diets to avoid them from being limiting

Question 38

Limiting AA

Answer 38

- When the supply of one essential AA is insufficient, protein synthesis is reduces - Which AA is limiting is specific to a feedstuff - Different feedstuffs may have different limiting AA

Question 39

In cereal grains (barley, wheat, corn), what is the first limiting AA?

Answer 39

Lysine - Threonine or typtophan is second limiting in many feedstuffs

Question 40

High protein diets vs. low protein diets in terms of limiting AA

Answer 40

High protein diets more likely to provide sufficient amounts of a greater number of essential AA Low protein diets - reduce N excretion, pollution - becomes more important to balance for a greater number of essential AA