Animal nutrition - feed intake

Question 1

The term „intake“ expresses

Answer 1

the daily consumption amount of natural feed, feed dry
matter, or any nutritive factor (ME, MP, etc.)

Question 2

Consideration of ration intake is the first step in

Answer 2

ration formulation

Question 3

In feeding, dry matter (DM) intake is

Answer 3

the most important, because this is limited by the
capacity of the digestive tract.

Question 4

DM intake =

Answer 4

feed amount – feed moisture

Question 5

DM intake is most commonly calculated in

Answer 5

kg per 100 kg live weight,
or in % of the animal’s body weight

Question 6

in farm animals, DM intake is about

Answer 6

2…5% of body weight,
in poultry slightly higher

Question 7

in dairy cows, DM intake is

Answer 7

in dairy cows 2.0…(3.0…3.5)…4.0 % of body weight

▪ if the ration contains only silage, then 2.2…2.5 %
▪ depends on the ratio of roughages to concentrates in the ration, i.e. the fibre content

Question 8

The lower the animal’s body weight is, the greater the

Answer 8

relative feed intake.

Question 9

Today, it is considered that high production cows eat more, because a lot of nutrients are excreted with the milk, and these nutrients must be received in the ration.

Thus, feed intake determines

Answer 9

the potential animal production!

Question 10

DM intake control is what type of process?

Answer 10

DM intake control is a neuro-hormonal process

Question 11

The food Intake controlling centre is located in

Answer 11

the hypothalamus

Question 12

According to a simplified scheme there are what two active centres involved in feed intake control

Answer 12

first: feeding centre, which motivates the animal to eat until an intake inhibiting signal is received from the other centre

second: satiety centre, which receives signals from the body about the intake, and if necessary inhibits the activity of the feeding centre

Question 13

How do Peptide hormones relate to feed intake control?

Answer 13

Peptide hormones have a central role in feed
intake control.

They provide the signals to the hypothalamus about the animal’s energy status.

Question 14

Most important peptide hormones are (4)

Answer 14

insulin
leptin (from adipose tissue)
ghrelin and gastrin (both synthesized in the GI tract)

▪ and others, like peptide YY, oxyntomodulin,
cholecystokinin, glucagon-like peptide 1 etc.

Question 15

What feeding related peptide hormones do not affect the hypothalamic satiety centre?

Answer 15

The exceptions are ghrelin (the so-called
“hunger-signalling hormone”, and thus affects
the feeding centre)

and gastrin (reduces the sensitivity of rumen tension receptors).

Question 16

Productive animals (dairy cows) intakes are
mainly determined by what 2 types of factors?

Answer 16

physical factors (these include chemical)
metabolic factors

Question 17

physical (and chemical) factors that detremine intake control are

Answer 17

related to total digestive tract capacity (rumen fill)

In practice, in dairy cows feed intake is limited at the beginning of lactation by the metabolic load, and at the second half of the lactation by the physical capacity of the rumen.

Question 18

metabolic factors that detremine intake control are

Answer 18

related to the animal’s ability to use feed energy

In practice, in dairy cows feed intake is limited
at the beginning of lactation by the metabolic
load, and at the second half of the lactation by
the physical capacity of the rumen.

Question 19

at the same growth phase grasses, compared to legumes, contain less

Answer 19

lignin, and therefore their digestibility is
higher which makes their intake / passage rate higher too

Question 20

at the same digestibility legumes, compared to grasses, contain less

Answer 20

cell wall and more intracellular substances,
and therefore their intake is ca 20% higher

Question 21

intense ammonia production in the rumen reduces

Answer 21

feed intake and in extreme cases can stop the
contractions of the forestomachs

Question 22

sugar and starch sources degrade in the rumen faster compared to

Answer 22

fibre sources (roughage to concentrate
ratio)

Question 23

passage rate of faster degradable feeds is higher, and therefore their intake is

Answer 23

higher

Question 24

acidic environment reduces rumen fibre digestion resulting in intake being…?

Answer 24

intake is lower

Question 25

rumen fibre digestion is associated with what type of bacteria?

Answer 25

rumen fibre digestion is associated with cellulolytic bacteria

Question 26

Digestibility of cellulose depends on

Answer 26

ruminal pH Digestibility of cellulose can be 98% at a pH of 6.4 ... 87% at 6.1 28% at 5.7 0% at 5.6

Question 27

At temperatures above 25°C, feed intake decreases by ?% for every 5°C

Answer 27

At temperatures above 25°C, feed intake decreases by 10% for every 5°C

Question 28

to avoid dairy cow overheating farmers can use

Answer 28

ventilators or water showers

Question 29

The maximum feed intake of cows is at what temperature?

Answer 29

The maximum feed intake of cows is at 7-10°C

Question 30

at the beginning of lactation the use of glucose in peripheral tissues...?

Answer 30

decreases, and majority amount of synthesised glucose is transported into the udder to support milk synthesis thus, insulin resistance is a normal state for high yielding dairy cows

Question 31

what type of effect growth hormone have when insulin content decreases?

Answer 31

antagonistic effect of growth hormone -> it increases, while insulin content decreases

Question 32

the main hormone in the blood which regulates the metabolism of carbohydrates (glucose)

Answer 32

insulin

Question 33

In monogastrics, what 2 hormones increase in the blood after feeding

Answer 33

glucose with insulin and leptin, increase in the blood, and due to this the animal stops eating

Question 34

In ruminants, at the beginning of lactation the glucose and insulin levels in blood are

Answer 34

low -> this stimulates gluconeogenesis in the liver and activates the enzyme lipase in adipose tissue

Question 35

In ruminants, at the beginning of lactation, tissue insulin resistance is high and due to this the increase of

Answer 35

glucose and/or insulin does not reduce the use of body fats use of body fats increases blood Non-esterified (“free” or unsaturated) fatty acids content and supresses intake

Question 36

In ruminants, as lactation progresses, the insulin content in blood, and tissue insulin sensitivity starts to

Answer 36

increase, and due to this feed intake increases

Question 37

The liver’s role in feed intake regulation is referred to as the?

Answer 37

hepatic oxidation theory The liver, as „hardware“, is connected to the intake centre in the brain via the hepatic vagus nerve. Feed intake is controlled via the stimulation intensity of the vagus nerve.

Question 38

Feed intake is controlled via the stimulation intensity of the vagus nerve. this is determined by

Answer 38

the amount of organic matter oxidised in the liver, and from this, ATP is produced

Question 39

reduced stimulation of the hepatic vagus nerve is associated with

Answer 39

a perception of satiety (more organic matter -> more ATP -> do not eat)

Question 40

increased stimulation of the hepatic vagus nerve is associated with

Answer 40

hunger (less organic matter -> less ATP -> eat)

Question 41

After calving dairy cow feed intakes are usually influenced by

Answer 41

metabolic load

Question 42

In the liver, two competing pathways work in parallel and in both the key compound is

Answer 42

oxalacetate

Question 43

In the liver two competing pathways work in parallel. What are they

Answer 43

1. Synthesis of glucose from propionate, AAs, and glycerol originating from adipose tissue 2. Oxidation of body FAs and VFAs into ATP

Question 44

In the liver two competing pathways work in parallel, and in both the key compound is oxalacetate. Which pathway is preferred?

Answer 44

2. Oxidation of body FAs and VFAs into ATP (1st being: Synthesis of glucose from propionate, AAs, and glycerol originates from adipose tissue) The second is preferred, and therefore the liver can convert propionate obtained from concentrates into ATP, which reduces intakes.

Question 45

Name 3 types of ruminal receptors that influence feed intake.

Answer 45

ToR – temperature receptors TR – tension receptors CR – chemo receptors

Question 46

Name 5 factors affecting feed intake in ruminants that aren't physicochemical or metabolic factors.

Answer 46

The animal itself per se (size and genotype) Composition of the feed ration Palatability of feeds Milk production Stage of lactation

Question 47

What attributes of feed composition affect feed intake (5)

Answer 47

silage quality, digestibility (amount and composition of cell wall substances), ration DM (ca 45%), level of feeding, roughage to concentrate ratio

Question 48

Cows eat ?% more wilted silage than unwilted silage.

Answer 48

Cows eat 16% more wilted silage than unwilted silage. It is believed, that due to dehydration, the volume of grass plant cells decreases, and therefore they can fit more easily into the rumen. The fine particles of the wilted silage pass through the rumen faster than unwilted silage particles.

Question 49

Cows eat most silage when its dry matter content is ?%.

Answer 49

Cows eat most silage when its dry matter content is 41.7%.

Question 50

Silage pH has a small impact on

Answer 50

feed intake

Question 51

NH3 is negatively correlated with

Answer 51

intake it is believed that intake is more inhibited by proteolysis intermediates, incl. biogenic amines, than ammonia per se

Question 52

Silage intake is most influenced by

Answer 52

acids produced VFA relative influences on intake: ▪ acetic acid -1,0 ▪ propionic acid -5,4 ▪ butyric acid -1,6

Question 53

the sum of the produced acids (incl. lactate) is important. if their amount exceeds 130 g/kg in DM, intake starts to

Answer 53

decrease

Question 54

Intensely fermented (biological inoculant) silage digestibility and feed intake is usually what? compared to extensively fermented (acidic preservative) silage digestibility?

Answer 54

lower than the extensively fermented (acidic preservative) silage digestibility

Question 55

The faster the silage pH decreases, the higher the

Answer 55

silage quality, the lower the nutrient loss and the higher the digestibility, and t he higher the intake is (less acids).

Question 56

The metabolic load is primarily related to the ability of the liver to

Answer 56

recycle the acids already produced in the silage and produced from feeds during ruminal fermentation.

Question 57

Each kilogram of concentrates in the feed ration reduces what?

Answer 57

silage dry matter intake – in case of lucerne silage 0.5 kg, and – in case of grasses 0.3kg

Question 58

the wetter the silage, the greater the depressive effect of the

Answer 58

concentrates

Question 59

Cows can eat a good silage dry matter at 15 kg, with 10 kg concentrates added. But if the silage is wet, what happens to its intake? And how about if the silage is dryish?

Answer 59

If the silage is wet and they're receiving 10 kg concentrate, silage intake will fall from 15 kg to 8 kg. If in the same case the silage is dry, intake will fall from 15 kg to 12 kg. This means wet silage with concentrates will have a depressive effect on intake and dry silage will not have quite as depressive an effect. Concentrates will always have a bit of a depressive effect on silage intake. (I guess)

Question 60

Feed intakes are controlled, in monogastric animals, by

Answer 60

the hormone insulin through the blood glucose level

Question 61

Feed intakes are controlled, in ruminants, by

Answer 61

the rumen fill and the amount of ATP produced by oxidation of organic matter

Question 62

What limits dry matter intake the most in practical feeding? A. Ration energy B. Ration crude protein C. Ration mineral elements

Answer 62

A. Ration energy

Question 63

Which feeds (DM) can dairy cows eat about 2% of their body weight of? A. Roughages & concentrates -> ratio 60:40 B. Silage & concentrates -> ratio 50:50 C. Roughages & concentrates -> ratio 90:10

Answer 63

C. Roughages & concentrates -> ratio 90:10

Question 64

Which hormones affect the body’s feeding centre and stimulate eating? A. leptin and ghrelin B. insulin and gastrin C. ghrelin and gastrin D. leptin and insulin

Answer 64

C. ghrelin and gastrin

Question 65

Which outside temperature ensures maximum intake for cows? A. -7...-10 °C B. -5...+5 °C C. +7...+10 °C D. +15...+20 °C

Answer 65

C. +7...+10 °C

Question 66

In which lactation stage is dairy cows feed intake regulated by metabolic factors? A. In far-off dry period B. At the beginning of the lactation C. In the middle of the lactation D. At the end of lactation

Answer 66

B. At the beginning of lactation In practice, in dairy cows feed intake is limited at the beginning of lactation by the metabolic load, and at the second half of the lactation by the physical capacity of the rumen.

Question 67

Which silage dry matter do cows eat the most? A. 25-30% B. 30-35% C. 35-40% D. 40-45%

Answer 67

D. 40-45% Cows eat most silage when its dry matter content is 41.7%.

Question 68

Which silage can cows eat more of? A. Wilted with high amount of total acids B. Wilted with low amount of total acids C. Wet with high amount of total acids D. Wet with low amount of total acids

Answer 68

B. Wilted with low amount of total acids Cows eat 16% more wilted silage than unwilted silage.

Question 69

When adding concentrates into the feed ration the roughage intake ... A. decreases B. increases

Answer 69

A. decreases Each kilogram of concentrates in the feed ration reduces silage dry matter intake.

Question 70

Oxidation of large amounts of organic matter in the liver ... A. increases intake B. decreases intake

Answer 70

B. decreases intake Feed intake is controlled via the stimulation intensity of the vagus nerve, this is determined by the amount of organic matter oxidised in the liver, and from this is produced ATP. Reduced stimulation is associated with a perception of satiety (more organic matter -> more ATP -> do not eat).