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BVetMed3 - PMVPH > Voluntary Feed Intake > Flashcards

Voluntary Feed Intake Flashcards

1
Q

What is the best measure of voluntary feed intake?

A

Dry matter intake

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2
Q

Why is voluntary feed intake important?

A

Production - want to maximise intake
Economics - want to optimise intake
Weight control - balance intake and expenditure
Weight loss- reduce intake

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3
Q

Which cows should NOT be losing weight?

A

Dry cows

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4
Q

What factors can decrease VFI?

A

Body fat
Pregnancy
Inert fill (similar to distension feedback)
Diet NDF

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5
Q

What does NDF stand for?

A

Neutral Detergent Fibre

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6
Q

How does distension feedback affect feeding of dry cows?

A

Feed dry cows to their abdominal fill needs
- Will continue to eat SAME VOLUME when lactating

Change quality/content to suit needs but keep volume the same

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7
Q

When does water affect VFI?

A

Water drunk WITH dry food - LITTLE EFFECT

Water IN plant material has significant effect

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8
Q

Why does water in plant material affect VFI?

A

Plants have to be broken down before water can be released - BULK is still there

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9
Q

What are NSPs and how can they affect feeding ?

A

Non- Starch polysaccharides / SOLUBLE FIBRE

Slows down the passage of feed and attracts fluids.

Better absorption of nutrients BUT reduced feed intake

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10
Q

What is the effect of giving chopped fibre?

A

Quicker transit

Increased feed intake

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11
Q

How is DMI related to transit time?

A

Increased dry matter intake results in shorter time spent in rumen/gut.

This affects how well nutrients are digested

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12
Q

What are feed tables for nutrient content based on?

How could this issue be overcome?

A

Maintenance level feed

NEVER occurs in dairy cows

Correction factors in modern software

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13
Q

What is inert fill?

How does it affect feeding?

A

Something in the abdomen (e.g. twins in cow or triplets in sheep) pushing on GIT

Intake drop, flow rate increases - POOR INTAKE

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14
Q

How can you counteract the effects of inert fill?

A

Feed more digestible feed to affected cows

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15
Q

What is the major factor affecting rumen outflow rate?

A

Particle size reaching the omasum

Pressure within rumen may have SOME effect in pushing feeds through

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16
Q

What affects particle size reaching the omasum (therefore rumen outflow rate)?

A

Ease of feed breakdown by chewing and fermentation

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17
Q

What effect can ruminal acidosis have on rumen outflow?

How might this be reflected in faeces?

A

More pressure in rumen due to stasis

May push through feeds without being fully digested

See indigested feed in dung

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18
Q

How can VFAs affect the rumen?

A

Feed back negatively on feed intake

Acetate and Proprionate almost same effect (Acetate slightly more effective)

Butyrate absorber slowe (as bigger) and more effective in causing ruminal stasis

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19
Q

What is heat stress in cows?

How does it affect feeding?

A

When it gets warmer, cows start eating less (above around 34 degrees)

20
Q

Outline the glucostatic theory of post digestive feedback.

What is the impact of this theory on ruminants?

A

If you have either a low glucose level in blood or a high glucose utilisation rate, it will trigger the hunger centre in the hypothalamus and therefore increase feed intake

LIMITED - short term control of appetite

21
Q

What are the main sources of glucose in ruminants?

A

Hepatic gluconeogenesis from amino acids and proprionic acid

22
Q

Why is the glucostatic theory of post digestive feedback of limited importance in ruminants?

A

Ruminant CNS is unusually INSENSITIVE to changes in blood glucose

23
Q

What is the Hepatic Oxidation Theory (HOT)

A

ATP levels in the liver determine the vagal stimulation

Low levels = stimulated hunger centre

24
Q

What are the sources of ATP in the liver?

A

VFA
Beta hydroxy butyrate - KETOSIS
NEFA - FATTY LIVER

These therefore feed back negatively on VFI

25
Q

What is leptin produced by?

What determines the level of leptin in the circulation?

A

fat tissue

More fat = more leptin in circulation

UNKNOWN role in domestic animals

26
Q

What is the role of leptin?

A

Inhibits hunger

27
Q

How could leptin be beneficial to dairy cows?

A

Energy deficit causes sustained reduction in leptin

Could benefit early lactating cows by promoting faster increase in feed intake and diverting energy from non-vital functions

28
Q

What factors affect how much an animal can eat?

A 
Weight 
Age 
Growth rate 
Production level
Health 
Environment
Non-production activity e.g. walking
Stress
Food palatability
Food type
Water 
Food availability
29
Q

How can we estimate the DMI of a dairy cow?

How might this vary for smaller animals?

A

2.5% body weigh (kg) + 10% milk yield (Kg)

Smaller animals, higher index

30
Q

What animals would be fed to be kept at maintenance balance?

A

Companion animals

31
Q

What is the energy requirement of milk production per litre?

A

5MJ/L

32
Q

What is the result of giving a ration that is too high in energy?

A

Rumen acidosis

33
Q

Why might weight loss during milking be beneficial?

A

CONTROLLED temporary negative energy

Decreased energy requirement for feed

Healthier rumen

34
Q

What are the sources of energy in forage?

How does their availability vary?

A

Cell contents - sugars, starches, proteins - 90% digestible, READILY AVAILABLE

Cell walls - cellulose, lignin, hemicellulose
SLOWLY AVAILABLE by fibre digesting bacteria
— good for bulk not energy requirement

35
Q

How does the percentage of lignin in a plant vary with age?

How does this effect digestibility?

A

INCREASES

Decreases as lignin is indigestible

36
Q

What does NDF stand for?

A

Non detergent fibre

37
Q

What are the constituents of NDF?

A

CELL WALLS

Hemicellulose,
Cellulose
Lignin

38
Q

How does %NDF affect feed intake ?

A

Measure of forage quality

Decreased NDF = increased intake

39
Q

What is acid detergent fibre?

What is it used to predict?

A

Cellulose and lignin

energy content of forage
Inversely related to digest ability

40
Q

What is the relationship between silage pH and intake?

How could this be explained?

A

Slight positive relationship at low pH

Adverse effect of acidity on fermentation need to eat more

41
Q

What are antinutritional factors?

A

Tannins
Lectins
Glucosinolates
Saponins

42
Q

What effect do tannins have at low and high quantities?

A

Low - destroyed in rumen

High - caustic to gut lining resulting in gut ulceration (oak poisoning)

43
Q

What are lectins?

How do they affect feeding ?

A

Glycoproteins found in legumes

Poor food utilisation and impaired growth

44
Q

What are glucosinolates?

How can they affect feeding?

A

found in cabbage and oil seed rape

Effects thyroid function

45
Q

What are saponins?

How can they affect feeding?

A

Found in soybeans peanuts sugar beets

Soapy - can affect rumen flora

46
Q

What ‘other’ factors (social, ration, cow) can affect VFI?

A

Feed space
Stocking density

TMR
Chopping length

Palatability
Adaptation time

BVetMed3 - PMVPH (8 decks)

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