1. Nutrients, Feed analysis and feed stuffs

Question 1

How many Joules in 1 Calorie?

Answer 1

4.184J

Question 2

How many Calories in 1 Joule?

Answer 2

0.239cal

Question 3

List the major functions of lipids within the animal (5 points)

Answer 3

• Supply energy for normal maintenance and productive functions
• Serve as a source of essential fatty acids
• Carrier of fat-soluble vitamins
• Integral constituents of the lipid bi layer
• Important for skin and hair coat condition.

Question 4

List the major symptoms associated with long-chain fatty acid deficiency

Answer 4

• Growth Retardation
• Increased permeability to water
• Increased water comsumption
• Increased suspectibilitiy to infections
• Infertility
• Capillary Fragility
• Kidney damage, haematuria and hypertension
• Decreased visual acuity
• Decreased myocardial contractility
• Decreased ATP synthesis in the liver and heart
• Decreased Nitrogen retention

Question 5

Construct the 3 major unsaturated fatty acid families, naming the key members of each family.

Answer 5

• N-9 (Omega 9) Non-essential Fatty Acid
  
  • Oleic Acid - 18:1, Palmitic Acid - 16:0, Steric Acid - 18:0
• N-6 (Omega 6) Essential Fatty Acid
  
  • Linoleic Acid - 18:2, Arachidonic Acir - 20:4
• N-3 (Omega 3) Essential Fatty Acid
  
  • Linolenic Acid - 18:3

Question 6

Define why a fatty acid is considered essential and list the key essential fatty acids (EFA) for different species

Answer 6

• A fatty acid is considered essential when the mammal cannot synthesise the fatty acid de novo - eg Linoleic acid (18:2 n-6) and Linolenic Acid (18:3 n-3) These acids must be supplied within the diet.
• In Cats Arachidonic Acid (20:4) is required within its diet as even though it is synthesised from linoleic acid, one of the desaturation steps is rate limiting and therefore production is slow.
• In poultry only linoleic acid 18:2 is essential

Question 7

Show and be able to explain the biochemical derivation of eicosanoids and EFA

Answer 7

Eiccsanoids include

• Prostaglandins
• Thromboxanes
• Leukotrienes
• Prostacyclines

and can be Pro-inflammatory (stimulate platelet aggregation, vasodilation, chemotaxis and immunosuppressive at high doses) or anti-inflammatory

Question 8

List the major oils as sources of fatty acids in the diet, and appraise each as a source of Linoleic and or Linolenic Acid

Answer 8

• Corn Oil
  
  • 70% linoleic acid (n-6)
• Safflower Oil
  
  • 78% Linoleic Acid (n-6)
• Sunflower Oil
  
  • 69% Linoleic Acid (n-6)
• Cottonseed Oil
  
  • 54% Linoleic Acid (n-6)
• Soybean Oil
  
  • 54% Linoleic Acid (n-6)
• Coldwater Fish Oils
  
  • 12-15% EPA (n-3)
• Flaxseed/Linseed Oil
  
  • 57% Alpha-Linolenic Acid (n-3)
• Canola Oil
  
  • 8% Alpha-Linolenic Acid (n-3)
• Soybean Oil
  
  • 7% Alpha-Linolenic Acid (n-3)

Question 9

List and explain the major functions of eicosanoids in the animal

Answer 9

Can be Proinflammatory or anti inflammatory

• Regulate Blood Clotting by stimulating platlet aggregation
• Blood Pressure - Vasodilator
• Smooth Muscle Contraction -
• Immune Response -Chemotaxis -Immunosuppressive at high doses

Question 10

Explain the biochemical and nutritional rationale for n-6, n-3 ratios in the formation of dog foods

Answer 10

By increasing n-3 in the diet inflammation can be reduced

Question 11

Define a nutrient in the context of animal nutrition

Answer 11

Any element of compound that is required for normal reproduction, growth, lactation or maintenance of life processes

Question 12

What are the major categories of nutrients

Answer 12

1. Proteins
2. Carbohydrates
3. Fats
4. Vitamins (Fat and water soluble)
5. Minerals
6. Water

Question 13

Define the term ‘energy’ and appreciate its importance in animal nutrition

Answer 13

Energy is not strictly a nutrient a nutrient, but is rather the “ability to do work”. Energy is the primary “nutrient” that is the essential driver of maintenance, growth and production.

Question 14

List the 8 categories of feedstuffs as defined by the National Research Council (USA)

Answer 14

1. Roughage: dry forages >18% crude fibre (DM)
2. Pasture, range plants, forages fed green (not cut & cured)
3. Silages
4. Energy Feeds: <18% Crude Fibre (DM); <20% crude protein (DM)
5. Protein Supplements: >20% crude protein (DM)
6. Mineral Supplements
7. Vitamin Supplements
8. Feed Additives

Question 15

Explain the revelance of the variation in nutrient composition that occurs between ingredients/feeds

Answer 15

Feeds consumed by animals vary enormously in their nutrient composition. This variation exists both between feedstuffs (ie different ingredients have different composition) but also within specific feedstuffs (ie there will be a range of nutrient composition profiles for different samplese of batches of a given ingredient.

Question 16

Explain the importance of collecting representative samples for analyses

Answer 16

You want to have many samples to give a more representative range of the feed measured.

Question 17

Outline the differences between wet chemistry and NIR methods for analysis.

Answer 17

1. Wet Chemistry is slow and costly, based of sound chemistry principals and are considered the most extact method of analysis
2. NIR Near Infrared Reflectance - Rapid and lowcost for predicting the nutrient value of forages and grains. Uses light and measures the interaction of electo-magnetic radiation with the matter in the sample to determine protein, fibre, energy and mineral content of feed samples.
3. The main advantages of NIR over wet chemistry is NIR is faster and cheaper. Another advantage is that the sample is not destroyed.

Question 18

Outline the generalised scheme for chemical (proximate) analysis fo feed stuffs

Answer 18

Proximate analysis partitions the consittuents of feeds into six chemical groupings used to predict nutritive value.

1. Crude Protein
2. Crude Fibre
3. Nitrogen- Free Extract
4. Crude Fat (or ether extract)
5. Ash
6. Moisture

Question 19

Proximate Analysis Flow Diagram

Answer 19