(117153) Nutrition

Animal Production Topic 1

Why do we need food?

Why do we need food?

1. Fuel (Energy) : Providing ATP generated from oxidizing dietary nutrients to drive all chemical processes among cells.

2. Raw materials : Provide the buildings blocks for biosynthesis.

3. Essential nutrients : Provide molecules for chemical reactions in the body.

List 4 processes that use ATP

1. Basal metabolism

2. Thermoregulation

3. Maintenance of cell structures

4. Transmission of nerve impulses

What happens to food once they are ingested?

1. Digestion : Provide energy for chemical reactions

2. Absorption : Used for tissue production or body secretions

3. Storage/Utilisation : Converted into food storage

What happens when nutritional requirements are NOT met?

1. Breakdown of storage depots or body tissues

• Lose body condition

2. Reduced production/performance

• Slower growth

• Less milk

• Illness

How do we ensure nutritional requirements are met?

1. Feed budgeting & planning

2. Partitioning & Nutrient fate

• Partitioning = Splitting up into smaller parts that are easier to work with

• Nutrient fate = Unabsorbed nutrients that become ‘lost’

What is the importance of nutrition?

1. Influence all stage of production

• Lactation —> Reproduction —> Gestation —> Birth —> Growth —> Slaughter

2. Amount of nutrition relates to :

a) Milk production

b) Health of female during pregnancy

c) Health of offspring

What are the 3 main components in diet?

1. Protein

• Essential amino acids

• Non-essential amino acids

2. Lipids (Fat)

• Saturated fatty acids

• Unsaturated fatty acids

3. Carbohydrates

• Structural [Weetbix]

• Non-structural

a) Soluble (Readily-fermentable) [Lollies]

b) Storage [Pasta]

State the 4 main stages of Food Processing

1. Ingestion (Mouth)

• Teeth : Break down particle size

• Saliva : Act as a buffer for food to enter the rumen; Act as lubricant to assist in swallowing

2. Digestion (Stomach)

• Chemical & Mechanical breakdown of food into molecules that are small enough to be absorbed

3. Absorption (Small intestine)

• Some nutrients transported in the blood or lymph system

• Some digestion occurs

4. Elimination (Large intestine)

• Undigested material passes out of the GI tract as faeces

• Last chance to absorb water out of the food material

• Bacteria fermentation

Give an example of a co-factor (helper molecule).

1. Metal ion

• Essential trace elements

• Cytochromes : Perform oxidation/reduction reactions

2. Vitamins & Vitamin derivatives

• Folic acid (Vit B9) : Synthesise DNA bases

State the steps for measuring dry matter.

Steps :

1. Weigh wet sample

2. Dry at 100C for 18hrs

3. Weigh dry sample

State the steps for measuring ash content.

Steps :

1. Weigh dry sample

2. Muffle furnace at 600C for 16hrs

• Muffle furnace : Lab instrument to isolate a material while heating them up to extremely high temperatures.

3. Weigh remaining ash

• Organic matter = 100% - Ash %

Briefly describe the 3 methods for measuring crude protein content.

1. Kjeldahl (pronounced: kel-dal)

• Digest with H2SO4 (Sulphuric acid) —> Titrate the ammonia (NH3) released

• Assuming that all N is released from protein, Protein = 16% —> 100/16 = 6.25

• Crude Protein = Total N x 6.25

2. Dumas

• Combust sample —> Measure N

3. HPLC

• Measure individual amino acids

State the method for measuring lipid content.

Ether extract

Briefly describe 3 methods for measuring carbohydrates.

1. Crude fibre

• Ether extract —> Residue boiled in acids & alkali —> Crude fibre residue

2. Nitrogen-free extract

• Remaining DM (Dry matter) after all analyses assumed to be the carbohydrate NFE

• NFE = 1,000 - (Ash + Crude protein + Ether extract + Crude fibre)

3. Van Soest Fibre system

• (Natural Detergent Fibre) Boil in neutral detergent —> Residue is Hemicellulose + Cellulose + Lignin

• (Acid Detergent Fibre) Boil in acid detergent —> Residue is Cellulose + Lignin

• Dissolve in 72% H2SO4 —> Lignin (Insoluble)

• Colourimetric = Non-structural CHO; Measures sugar & starch

What is the digestive tract structure & function?

1. Hindgut (Mouth, Lips, Teeth, Tongue)

• (Prehension) Bring food → mouth

• (Mastication) Chewing

• Tasting

2. Foregut (Oesophagus, Stomach)

• Moving food → stomach

• Store, Mix, Absorb (a bit of) food

• Chemical & Physical breakdown of food

• Mediate flow of digesta → midgut

3. Midgut (Small intestine)

• Principal site of digestion for monogastrics

• Absorption & Mixing

4. Hindgut (Caecum, Large intestine, Rectum)

• Complete absorption of water & minerals

• Fermentation of bacteria to aid digestion

a) Monogastric : Caecum

b) Ruminant : Stomach

What are the processes of digestion?

1. Ingestion

• Teeth

(i) Obtain food

(ii) Reduce particle size

• Saliva

(i) Lubrication

(ii) Enzymes for initial digestion

2. Digestion

• Stomach

(i) Chemical & Mechanical breakdown

(ii) Receives & Stores ingested food

(iii) Start of absorption

(iv) Some absorption

3. Absorption

• Small intestine

(i) GI tract cells take up small molecules → Blood/Lymph → Body cells

(ii) Completion of digestion

(iii) Large surface area of absorption

4. Elimination

• Large intestine

(i) Water absorption

(ii) Bacterial fermentation

How does the digestive processes differ between animal types?

1. Ruminant

• Multi-chambered foregut to assist digestion of a fibrous diet

• Rumen microbes

2. Monogastric

• Single stomach that relies heavily on enzyme digestion

3. Pre-gastric = Bacterial fermentation in the stomach (usually rumen) [Foregut]

4. Post-gastric = Bacterial fermentation in the caecum & large intestine [Hindgut]

What are the end products of digestion? How do they differ between animals?

1. Monogastric (Small intestine)

• Carbohydrate → Simple sugars

• Protein → Amino acids

• Fat → Fatty acids & Monoglycerides

2. Ruminant (Rumen)

• Carbohydrate (Starch) → VFA

• Carbohydrate (Cellulose) → VFA + Gas (CO2 + methane)

• Protein → Ammonia

3. Ruminant (Small intestine)

• Protein → Microbial protein + Amino acids

• Fat → Fatty acids + Glycerol

Compare the digestive processes between monogastrics & ruminants?

Both monogastrics & ruminants have the same processes occurring in the small intestine (midgut) and the caecum & large intestine.

1. Mouth

• Monogastric = alpha-amylase breaks down starch

• Ruminant = -

2. Stomach

• Monogastric = Secretes HCl & pepsin to digest protein

*Gastric juice = HCl + pepsin = Prevent infection from reaching the small intestine

• Ruminant (Rumen - Reticulum) = Microbes…

(i) Produce enzymes for fermentation

(ii) Saturate fat

(iii) Use non-protein N to create protein

• Ruminant (Abomasum) = Enzyme digestion (like a monogastric)

What are the processes of metabolism?

OR

Outline the fate of absorbed nutrients.

(Monoastric) Simple Sugars

• Phosphorylated to glucose-6-phosphate (C6H13O9P)

• 5 major metabolic routes :

1. Oxidative degradation → CO2 + H2O + energy

2. Convert to glucose → in tissues in brain/udder

3. Storage to glycogen → in liver & muscles

4. Convert to fatty acid + cholesterol for fat synthesis

5. Degradation via Pentose Phosphate Pathway (PPP) → NADPH (→ electron donor/reducing power/anabolic reaction)

(Ruminant) Volatile Fatty Acids (VFA)

• TCA cycle → CO2 + H2O + energy (ATP)

Amino acids

• Absorbed by small intestine → Transported via portal blood to liver

• 4 metabolic pathways

1. Transport to tissues for protein synthesis

2. Synthesis of liver & plasma proteins

3. Conversion to nucleotides

4. Catabolism with ATP production

*Catabolism : Breakdown complex → simple molecules

• For ruminants, ammonia (end product of digestion) → urea → recycled back to rumen → excreted in urine

Fatty Acids & Glycerol

• Taken up by adipose tissue → Stored as triglycerides

• Taken up by mammary cell → Secreted in milk fat

• Esterification of glycerol with fatty acids for fat synthesis

• Fatty acids arise from

a) Circulatory lipids

b) Synthesised from acetate & beta-hydroxybutyrate

• Liver : Hydrolysis of triglycerides → fatty acids → 5 routes

1. Oxidation → CO2 + ATP

2. Formation of ketones

3. Synthesis of cholesterol & bile salts

4. Synthesis of plasma lipoproteins

5. Formation of plasma-free fatty acids

What are the main energy components from foods which animals catabolise to generate energy?

• Carbohydrates

• Lipids (Fat)

• Protein

• Secondary compounds

• Vitamins

Describe the major chemical components of the animal body.

Feed → Dry Matter + Water

Dry Matter (DM) → Ash + Organic matter

• Ash = Minerals & Inorganic matter

Organic matter = Protein + Lipid (Fat) + Carbohydrate + Secondary compounds + Vitamins

• Protein = Essential & Non-essential amino acids

• Lipid = Saturated & Unsaturated

Carbohydrate → Soluble + Storage + Structural

• Soluble = Pectin, Fructans, Monosaccharides, Disaccharides

• Storage = Starch

• Structural = Cellulose + Hemicellulose

Secondary compounds = CT + SMCO + Lignin

Vitamins = Water-soluble + Fat-soluble

*Fibre (Cell wall) = Hemicellulose + Cellulose + Lignin

Describe in broad detail the proximate analysis of feedstuffs.

Dry Matter

Steps :

1. Weigh wet sample

2. Dry at 100C for 18hrs

3. Weigh dry sample

Ash

Steps :

1. Weigh dry sample

2. Muffle furnace at 600C for 16hrs

• Muffle furnace : Lab instrument to isolate a material while heating them up to extremely high temperatures.

3. Weigh remaining ash

• Organic matter = 100% - Ash %

Crude Protein

1. Kjeldahl (pronounced: kel-dal)

• Digest with H2SO4 (Sulphuric acid) —> Titrate the ammonia (NH3) released

• Assuming that all N is released from protein, Protein = 16% —> 100/16 = 6.25

• Crude Protein = Total N x 6.25

2. Dumas

• Combust sample —> Measure N

3. HPLC

• Measure individual amino acids

Lipids

• Ether extract

Carbohydrates

1. Crude fibre

• Ether extract —> Residue boiled in acids & alkali —> Crude fibre residue

2. Nitrogen-free extract

• Remaining DM (Dry matter) after all analyses assumed to be the carbohydrate NFE

• NFE = 1,000 - (Ash + Crude protein + Ether extract + Crude fibre)

3. Van Soest Fibre system

• (Natural Detergent Fibre) Boil in neutral detergent —> Residue is Hemicellulose + Cellulose + Lignin

• (Acid Detergent Fibre) Boil in acid detergent —> Residue is Cellulose + Lignin

• Dissolve in 72% H2SO4 —> Lignin (Insoluble)

• Colourimetric = Non-structural CHO; Measures sugar & starch

Why, during the determination of crude protein content, is nitrogen multiplied by the factor 6.25?

Assuming that all N is released from protein, Protein has 16% N → 100/16 = 6.25

What chemical components are found in the acid detergent fibre & neutral detergent fibre?

Acid detergent fibre = Cellulose & Lignin

Neutral detergent fibre = Hemicellulose & Cellulose & Lignin

Describe the different parts of the mammalian digestive tract.

1. Lips, Mouth, Teeth

2. Stomach

• Smooth elastic wall

• Wall is folded (rugae) to allow for expansion

• Mucous membrane contains glands that secrete acid & digestive enzymes

3. Small intestine

• 3 areas (Duodenum, Jejunum, Ileum)

• Has villi to increase absorptive surface

4. Caecum

• Contains microorganisms that ferment food

• Smooth surface (No villi)

• Pouch-shaped (“Blind sac” nickname) & may have folds

5. Large Intestine

• Contains some bacteria

• Absorbs water

• No villi

• Cells in mucosa secretes mucus

  • Mucosa = Moist inner lining of some organs & body cavities

6. Rectum

Describe the avian digestive tract. What special features does the bird possess which support a high digestive efficiency?

1. Mouth

2. Oesophagus

3. Crop

• Enlarged area of oesophagus

• Food storage

• Adds moisture to soften food prior to entering stomach

4. Proventriculus

• Glandular stomach

  • Mucus secretion to protect stomach lining from effects of HCl

• Chemical digestion using HCL & digestive enzymes (pepsin)

5. Gizzard

• Muscular part of the stomach

• Mechanical digestion

  • Grinds & Mixes food

6. Small intestines

7. Caecae

• Birds have multiple caecum called ‘caecae’

6. Cloaca

Special feature

Shorter intestinal tract

• Can quickly turn food → fat for storage

• Shorter digesta retention → Less weight for flight efficiency

Describe the foregut of the ruminant. Why have ruminants evolved a specialised foregut?

Rumen → Reticulum → Omasum → Abomasum

• Rumen

  • Microvilli (Papillae lining)

  • Digestion & Fermentation vat

  • Has rumen microbes

• Reticulum

  • Honeycomb

  • Captures longer particles to be regurgitated back up

• Omasum

  • Folded lining (Straight folds)

  • Intense water absorption (60% removed) → Solid & hard digesta

• Abomasum

  • (Messy folds)

  • True gastric stomach (Like monogastric) with digestive secretions

  • pH decreases from 6.5 → 2.5

    • Denature proteins

    • Kill bacteria & pathogens

    • Dissolves minerals

    • Gastric digestion

  • Last chance to get nutrients from food

Reason

To digest fibre

Describe the development of the bovine foregut from birth to maturity.

Calves are basically monogastrics

• Milk directly goes into abomasum

• Suckling creates a reflex that shuts off the rumen & allows passage into omasum

• Omasum only captures long particles so milk passes through to abomasum

• Reticular group shuts

  • If the milk does go into reticulum, fermentation will occur → Won’t release the right nutrients

What are the products of digestion of foods :

• Carbohydrates

• Proteins

• Lipids?

Why are digestive enzymes important to the animal? What are the major preenzymes & enzymes responsible for digestion of the main components of feed?

Importance of Digestive Enzymes

• Breakdown & digestion of food

• Help absorb nutrients

Major preenzymes & enzymes

What is rumination? Why is physical reduction in feed particle size an important determinant of intake rate of ruminants?

Rumination (Chewing cud)

• Physical digestion

• Increases surface area of food for microbes in the foregut (stomach)

Reasons

• Increased dry matter intake

• Increased organic matter digestibility

• Efficient digestive function

List the type of micro-organisms present in the rumen, their approximate numbers (where given) and their role in digestion.

1. Fungi

• Grow down into plant material

• Fibre degradation & digestion

2. Protozoa

• Fermentation

• Utilise dietary soluble carbohydrates & insoluble protein

• Engulf starch/bacteria

3. Bacteria

• Fermentation

• Break down CHO & lipids

• Convert carbohydrates → VFA

• Convert amino acids → ammonia

• Saturate fatty acids

• Protein contributes to animal’s protein supply

General functions

• Carbohydrate (Starch, Cellulose) → VFA → Fat in cells OR Glucose in liver OR Degraded via TCA cycle to release energy

• Production of enzymes that ferment food

• Saturate fat

• Use non-protein N to create protein

• Provide 70 - 90% of a cow’s protein requirements

What are the main end products of carbohydrate digestion in the rumen & what happens to them subsequently? How does the form in which energy reaches the body tissues differ between ruminants & monogastric animals?

Describe why a ruminant animal can survive and grow on a diet devoid of dietary protein whereas a pig cannot.

Ruminant animals have microbes in their rumen that can synthesise protein using N, and thus require no dietary protein.

Monogastric animals like pigs are unable to do so, so they require dietary protein to survive.

In what circumstances would you advocate feeding a urea-based supplement to beef cattle? Explain your decision.

1. Cost-effective

• Effective source of protein

• Urea is a non-protein N compound → Rumen microbes can use non-protein N to create protein

• Urea → Ammonia + CO2 + protein

a) Ammonia → Microbial protein

b) Ammonia → Detoxified in liver → Excreted in urine

2. Dry season = Poor-quality grazing

3. Low protein but high energy

• Boosts microbial protein synthesis in low true protein diets

• Proper protein intake

Why are the body lipids in ruminants generally in saturated form?

Unsaturated fatty acids are toxic to many rumen microbes, especially those involved in fibre digestion.

Saturated fatty acids provide an energy source for the animal.