Animal nutrition - rumen acidosis, milk fever

Question 1

Main factors related to rumen acidosis (3)

Answer 1

• Low fibre content and/or lack of effective fibre
  (mostly the lack of effective fiber)
• High percentage of cereals/concentrates in ration DM
• Low rumen buffering capacity

Question 2

Pathogenesis of acidosis

Answer 2

ruminal atony

Question 3

Clinical rumen acidosis is rare, but if it occurs the following happens: (5)

Answer 3

– fore-stomach contractions stop
– protozoa and cellulolytic bacteria die
– no digestion takes place (at least cellulose digestion stops)
– lactate is the main acid in the rumen
– treatment is hard and the disease often ends in death

Question 4

Acidosis mostly occurs in what form

Answer 4

in the subclinical form (SARA), which is associated with many diseases and problems in the herd

Sub-acute ruminal acidosis (SARA)

Question 5

Name 6 potential consequences of Sub-acute ruminal acidosis (SARA).

Answer 5

laminitis
low milk fat content
displaced abomasum
decreased fertility
ketosis
mastitis, metritis

Question 6

Clinical acidosis appears when rumen pH is

Answer 6

< 5.0

– Predominant bacteria is Streptococcus bovis which produces lactic acid
– Bacteria that consume lactic acid disappear

Question 7

In the case of subclinical acidosis, the rumen pH is mostly between

Answer 7

5.5- 5.6

– Subclinical acidosis is not necessarily caused by a high amount of lactic acid in the rumen -> the amount of total acids is more important.

Question 8

At a pH of 6.0 in the rumen, the lactate isomers are equal to what percentage of total acids?

Answer 8

D-lactate, and L-lactate only 20%.

If the pH drops to 5.0 the proportion of produced lactate isomers equalise (50:50).

Question 9

If the pH drops to 5.0, the proportion of produced lactate isomers do what?

Answer 9

equalise (50:50)

Question 10

Previously was wrongly thought that main acidosis
causer is L-lactate, which absorbs heavily.

Today is known that both isomers, D and L lactates, do what?

Answer 10

Today it is known that both isomers absorb at equal rates, converted into BHB and are used in the peripheral tissue (incl. rumen epithelia cells) as energy source.

they metabolises in slightly different pathways but with the same efficiency

Question 11

Surplus of lactic acid causes

Answer 11

subclinical acidosis,
more frequent shortly after calving when feeding is changed within a short period from silage-based to a cereal-based ration.

In this case there are more bacteria producing lactic acid than there are bacteria consuming it.

Question 12

Recovery time of bacteria in the rumen varies:
– bacteria producing lactic acid, how long?
– bacteria consuming lactic acid, how long?

Answer 12

– bacteria producing lactic acid -> 2-3 weeks
– bacteria consuming lactic acid -> 4-5 weeks

Question 13

Rumen papillae reach their maximum length at what point?

Answer 13

Rumen papillae reach their maximum length at 4 to 5 weeks after calving.

Question 14

Rumen epithelial cells are not similarly protected as abomasum epithelial cells, and therefore

Answer 14

organic acids produced in the rumen injure them easily

Question 15

Low rumen pH causes (4) morphological changes

Answer 15

rumenitis,
rumen parakeratosis,
erosion of the epithelial cells
and ulcers

Question 16

In normal nutrition conditions the lactic acid
produced in the rumen will be used/consumed by what bacteria specifically (latin name)?
Whats their pH optimum?

Answer 16

the bacteria Megasphera elsdenii, whose pH optimum is 5.5- 6.0

Question 17

If the acidity in the rumen increases and the
pH drops below 5.5, what type of bacteria prevail?
latin name?

Answer 17

lactic acid producing bacteria Streptococcus bovis start to prevail, whose pH optimum is 5.1- 5.3

Question 18

name the species of lactic acid producing bacteria and the species of lactic acid consuming bacteria

Answer 18

lactic acid used by Megasphera elsdenii,
lactic acid producing bacteria Streptococcus bovis

Question 19

At pH 5.1-5.3, what type of changes occur in the rumen and its microflora?

Answer 19

– the rumen papillae fall down/wither, epithelia damaged (rumenitis)

– bacteria named Fusobacterium necrophorum, reproduce quickly, which enter through injured rumen wall into the blood stream

Question 20

Fusobacterium necrophorum are characterized as (what type of respiration)

Answer 20

facultative anaerobes

Question 21

When Fusobacterium necrophorum enter the liver they

Answer 21

break up liver tissue,
feed on lactic acid produced during glycogenesis/glycogenolysis,
and encapsulate themselves in the liver’s serous membrane which results in liver abscesses.

Question 22

incidence of liver abscesses in cattle fed high concentrate diets range from

Answer 22

10 to over 50%

Question 23

why does epistaxis occur in SARA/ruminitis sometimes?

Answer 23

occurs secondarily to bacterial pneumonia or caudal vena cava
syndrome, both of which can be traced back to SARA induced rumenitis.

blood specifically originating from the lungs (not the nasal cavity)

Question 24

Which cows are most vulnerable to rumen acidosis

Answer 24

Those in the post-calving period, when rumen microflora are not adapted to high amounts of concentrate .

(adaptation to ration includes microbial population, papillae development)

Question 25

Cows with a high DM intake and/or who are fed a badly balanced ration are most susceptible to what

Answer 25

rumen acidosis

Question 26

what makes it possible to sort concentrates from the total mixed ration?

Answer 26

dry or coarse-chopped forage makes it possible for the cows to sort concentrates from the rest

Question 27

classic feed to induce rumen acidosis in the early post-partum period

Answer 27

excess of grain (rapidly digestible starch, e.g. high moisture cereals)

Question 28

Signs of subclinical rumen acidosis (4)

Answer 28

* decreased and varying dry matter intake * Undigested grains and fibre parts in the faeces (high passage rate, the feed stays in the rumen only for a short time ) * Milk fat content decreases * Limping, and cows with laminitis in the herd

Question 29

Why does milk fat content sometimes decrease in cows with subacute ruminal acidosis (SARA)?

Answer 29

Due to reduced pH (below 6) in the rumen – decreased amount of acetic acid produced (previous theory) – its been found that changes in the PUFA’s biohydrogenation pathways, and the produced FA intermediates (C18:2 t10, c12 (linoleic acid)) actually inhibit milk fat synthesis

Question 30

Note, that if a high amount of a PUFA-rich feed is fed the milk fat content does what

Answer 30

decreases, even when cows are not in acidosis! so its the ration PUFA content that can inhibit milk fat synthesis and thus decrease its concentration

Question 31

maximum amount of PUFAs per ration

Answer 31

should not exceed 25 g/kg DM

Question 32

3 methods to Prevent acidosis in order of importance

Answer 32

1. ration should contain adequate amounts of effective fiber 2. regulate starch amount and pay attention to the starch sources (rate of digestibility etc.) 3. Add sodium bicarbonate to the rations

Question 33

effective fiber prevents acidosis how?

Answer 33

prickly rough roughage stimulates the ruman epithelium (aids rumination) and salivary production, thus increases the rumen's buffer capacity and increases pH

Question 34

grass silage % DM in a ration should be about 50%. if grass and maize silage are fed together, what should be taken into account?

Answer 34

that maize silage also contains starch and sugars which must be adjusted for 260- 300g/kg DM mentioned in lecture but not sure exactly what - could be max. allowable starch content

Question 35

which cereals are digested faster than others?

Answer 35

from fastest to slowest digestion = barley > wheat/rye/triticale > oats > corn meal

Question 36

what physical factor affects grain digestion speed?

Answer 36

from fastest to digest to slowest = high moisture > ground/milled > cracked/crushed

Question 37

NaHCO3 is useful for?

Answer 37

sodium bicarbonate buffer can prevent acidosis if added to the ration at an amount of ≥ 0.5 kg per day to have any effect must be at minimum half a kg per ration

Question 38

Feeding additional yeast cultures can help to..? At what dose?

Answer 38

help in the prevention of acidosis. the theory is that they suppress the lactic acid producers and promote the lactic acid utilizers the yeast may be added at doses such as 50g/day into the mineral additive portion of the ration e.g. Saccharamyces servicie note: lecturer doesn't believe this theory but he presented it nonetheless

Question 39

Functions of saliva (5)

Answer 39

* Helps to moisten feeds * Ensures body's water balance * Avoids bloat * Ensures nitrogen recycling * Neutralises acids (is an endogenous buffer, pH > 8.1...8.9)

Question 40

what percentage of water enters into the rumen via saliva

Answer 40

70%

Question 41

how does saliva aid in avoiding bloat development?

Answer 41

saliva has antifoaming properties

Question 42

salivary pH is

Answer 42

8.1...8.9 an endogenous buffer so ruminant saliva neutralises acids acids in the rumen are both produced there and gotten from acidic feeds (silage, e.g. 4.2-4.7 -> 6.0-6.5)

Question 43

Amount of saliva produced depends on

Answer 43

effective fiber & rumination activity

Question 44

cows can produce how many liters of saliva per kg of ration dry matter

Answer 44

10-32 litres

Question 45

saliva production can be how much higher when the ration contains more roughages instead of concentrates

Answer 45

about 5 times higher when the ration contains more roughages instead of concentrates

Question 46

rumen pH depends on

Answer 46

the amount of saliva (and other factors but this is a big one)

Question 47

Correlation between ration NDF content and rumen pH is

Answer 47

weak

Question 48

describe Chemical fibre

Answer 48

– NDF (min 26%), ADF (min 19%), CF (min 14%) – has low nutritional value; is measured in the laboratory; characterises plant cell wall substances

Question 49

Effective fibre (feed physical properties) ensures (5)

Answer 49

– normal ruminal digestion – rumen acidity -> pH – rumination activity – saliva production – sufficiently high milk fat content

Question 50

Possibilities of checking the amount/presence of effective fibre (3)

Answer 50

▪ Sifting of feed particles (if there is less than 7% long feed particles in the TMR there is a high risk of SARA) ▪ Count the ruminating cows -> at least 50% of laying cows and 40% of standing but not eating cows should be ruminating ▪ Sensorally -> prepared TMR should prick your own hand

Question 51

What are you counting when Counting the ruminating cows

Answer 51

looking for signs of appropriate presence of effective fiber at least 50% of laying cows and 40% of standing, but not eating, cows should be ruminating

Question 52

Biogenic amines are formed mainly by

Answer 52

decarboxylation of amino acids in feeds when other sources for producing ATP are in short supply

Question 53

Biogenic amines are produced in the

Answer 53

rumen or in the large intestine as a result of microbial fermentation, primarily when energy is deficient

Question 54

Amino acids that may be decarboxylated when microbes are deficient of other energy sources (5)

Answer 54

Arginine -> Putrescine + CO2 Glutamine -> γ – aminobutyrate + CO2 Histidine -> Histamine + CO2 Tryptophan -> Tryptamine + CO2 Tyrosine -> Tyramine + CO2

Question 55

Endotoxins, lipopolysaccharides, may be produced in the rumen and can play a role in the etiology of

Answer 55

laminitis

Question 56

especially what two species of gram negative rumen bacteria produce ruminal endootoxins

Answer 56

Megasphera elsdenii and Selenomonas ruminantium

Question 57

Endotoxins reduce rumen (3)

Answer 57

motility, promote rumenitis and laminitis

Question 58

Laminitis is a

Answer 58

Multifactorial disease, related to low rumen pH and histamine concentration in rumen and blood. Acidosis increases the blood flow. Blood pressure increases due to endotoxins and histamine production Histamine is a vasoactive amine which causes arterial constriction and permeability of the blood vessels. Blood vessels break, bleed and bruise.

Question 59

Laminitis and histamine theory

Answer 59

multifactorial disease centering around histamine release

Question 60

Reasons related to feeding that cause laminitis (5)

Answer 60

* High proportion of rumen fermentable concentrates in the ration * Lack of effective fibre * Lower saliva production * Deficiency of minerals * Deficiency of vitamins

Question 61

How to strengthen hooves? (4)

Answer 61

* Check nutrients needed for the keratinisation process * Amino acids (especially those which contain sulfur such as cysteine and methionine) * Minerals * Vitamins

Question 62

amino acid with the most important role in the keratinisation process

Answer 62

cysteine with the sulphur contained in it

Question 63

most important minerals for hoof health (5)

Answer 63

calcium, copper manganese selenium, zinc

Question 64

most important vitamin for hoof health

Answer 64

biotin -> needs longer feeding (10-20 mg per day)

Question 65

Displaced abomasum is a disease caused by

Answer 65

low ration fibre content and low rumen fill * Reasons are – low amount of effective fibre – large amount of easily digestible fibre in the pre- and post calving rations (pectin, hemicellulose -> distillers & brewer’s grains, soyabean hulls etc.) – large amount of rumen fermentable concentrates

Question 66

Displaced abomasum Usually appears

Answer 66

in the first month after calving

Question 67

Milk fever is a

Answer 67

calcium metabolism-related disease, which occurs most frequently in high yielding dairy cows up to 48 hours after calving, less often before calving

Question 68

In milk fever, the cow's body cannot mobilize what?

Answer 68

calcium from either bones (resorption) nor from feed (absorption)

Question 69

What hormones may be inactive during milk fever?

Answer 69

parathyroid hormone (PTH) but also, enzyme 1α-hydroxylase (catalyzes the synthesis of the active form of vitamin D), and the vitamin D metabolite [1,25(OH)2D3] are inactive

Question 70

What receptors may be insufficient in number during milk fever?

Answer 70

insufficient number of Ca-mobilizing hormone receptors in target tissues (bones, intestine)

Question 71

In the dry period, the cow’s calcium requirement is very low – about

Answer 71

20g /day

Question 72

grass-legume mixture silages canccontain Ca in excess of

Answer 72

10g/kg DM

Question 73

due to calcium oversupply what happens?

Answer 73

calcitonin is active and the excess calcium is excreted via faeces

Question 74

1 kg of colostrum contains how much Ca+?

Answer 74

2.5g of calcium per kg of colostrum

Question 75

For colostrum production, calcium is removed from where?

Answer 75

body fluids and from peripheral tissues into milk

Question 76

clinical signs of milk fever (2)

Answer 76

the animal is unable to rise, and the rear of the body becomes insensitive muscles cease contracting and nerve impulses are no longer transmitted

Question 77

Feeding strategy to reduce hypocalcaemia (milk fever)

Answer 77

The idea of the strategy is to activate „wake up“ parathyroid hormone (PTH) at calving time. In the dry period the Ca requirement is low and PTH is inactive. * Strategy must increase Ca availability either from feeds or from bones. * Two possibilities: – feed low Ca-containing ration to activate PTH or – induce metabolic acidosis

Question 78

Two possibilities for activating PTH

Answer 78

– feed low Ca-containing ration to activate PTH or – induce metabolic acidosis

Question 79

(CAB)

Answer 79

(dietary )Cation-anion balance Body’s acid-base balance can be influenced by positively charged ions [cations -> potassium (K+) and sodium (Na+)], and by negatively charged ions [anions -> chlorine (Cl-) and sulphur (S2-)] potassium sodium chloride sulphur are used to calculate this dietary balance

Question 80

Metabolic acidosis can be induced when

Answer 80

anionic salts are fed to cows. This induces a shift in the cation-anion balance which can stimulate PTH to "wake up".

Question 81

Negative Cation-anion balance in the ration results in (4)

Answer 81

– increases Ca mobilizaton from the bones – activates Ca absorption mechanisms – reduces hypocalcaemia – prevents milk fever

Question 82

It is Mostly recommended that the prepartum ration Cation-anion balance should be from

Answer 82

-100 to -250 mEg/kg DM – no clear agreement between researchers

Question 83

If the CAB is < 250 mEq/kg we can use

Answer 83

Anionic salts to shift this balance and thus increase the Sensitivity of PTH receptors

Question 84

if the CAB is > 250 mEq/kg we can administer

Answer 84

feed with Low ration Ca content < 20 g/day, Vitamin D analogues (increase Calciotropic hormones) or Ca gels, pastes, rumen boluses (Passive absorption)

Question 85

describe using anionic salts as a Feeding strategy to avoid hypocalcaemia

Answer 85

Anionic salts -> feed only 2-3 weeks before calving. – the most advanced and simplest way to avoid hypocalcaemia; can be easily used in the composition of TMR

Question 86

in order to avoid hypocalcemia, keep K

Answer 86

as low as possible (<1.2%), + narrow ratio of Ca:P (1.3 : 1)

Question 87

in order to avoid hypocalcemia, Add anionic minerals into the ration but also reduce

Answer 87

amount of cationic feeds in the ration

Question 88

Adding anionic minerals into the ration (but also reducing the amount of cationic feeds in the ration) – decreases what?

Answer 88

decreases metabolic alkalosis and shifts the organisms acid-base balance towards metabolic acidosis – this helps after calving to increase the availability of Ca from bones and Ca absorption from small intestine

Question 89

describe Oral administration of CaCl2 give a pro and a con

Answer 89

Calcium chloride is an inorganic compound used to avoid hypocalcemia and consequent milk fever. administer 2...3 times if a water solution, before and after calving; is effective, but vary labour intensive as a paste/gel administer 2...3 times -> during calving, 12h and 24h after calving Pro: both decrease blood pH, which stimulates Ca-releasing hormones Con: both have corrosive effects and can, in excess, induce metabolic acidosis, which reduces feed intake

Question 90

describe Oral administration of Ca-propionate paste/gel give a pro and a con

Answer 90

has slower effect than CaCl2 Pro: blood acidifier effect is missing and propionate is a glucose precursor in gluconeogenesis Con: contains a smaller amount of Ca and therefore the administration amount should be large than CaCl2

Question 91

How does calving affect the immune system

Answer 91

Ability of the immune system declines with respect to calving – the ability of neutrophils to destroy invasive bacteria in the body decreases about 40% – the ability of lymphocytes to produce antibodies decreases by about 30%

Question 92

Effect of hypocalcaemia and milk fever on immunity

Answer 92

As a result of Ca deficiency – increased cortisol secretion, which in turn can cause retained placenta – decreases muscular tone (cortisol = flabby smooth muscles), as a result: ▪ a flabby teat sphincter can allow bacterial invasion resulting inmastitis ▪ flabby uterus muscle -> retained placenta -> bacterial invasion -> metritis

Question 93

Possibilities to strengthen the immune system (2-3)

Answer 93

* Ensure the necessary metabolisable protein level (glutamine!) * Ensure requirements for the following are met (on DM basis in kg): – vitamins A (7500 IU) and E (60 IU) – Copper (15mg) , zinc (60mg), selenium (0.3mg) – check iron content

Question 94

high iron cotent can compete with what other mineral

Answer 94

can impede assimilability of copper Also note, * Free iron ion generates free radicals in the tissues, which cause "oxidative stress„ * Free iron ions required by bacteria = too much iron bad

Question 95

Iron content should be – in the ration ? mg per kg DM – in drinking water ? mg per litre

Answer 95

– in the ration ‹ 750 mg per kg DM – in drinking water < 0.4 mg per litre * Free iron ion generates free radicals in the tissues, which cause "oxidative stress„ * Free iron ions required by bacteria

Question 96

How much time is needed to recover the population of lactic acid consuming bacteria?

Answer 96

B. 4-5 weeks

Question 97

What is the most important nutritional tool to avoid subclinical SARA? A. Adding high moisture barley B. Using buffers C. Increase amount of effective fibre D. Using yeast cultures

Answer 97

C. Increase amount of effective fibre

Question 98

What kind of relationship is between ration fibre (NDF) content and rumen pH ? A. Weak B. Medium C. Strong

Answer 98

A. Weak

Question 99

Which minerals we should look when we form close-up dairy cow ration? A. Ca, P, K, Na and Mg B. Ca, P, Cl, S and Mg C. Ca, P, K, Na, Mg, Cl and S

Answer 99

C. Ca, P, K, Na, Mg, Cl and S

Question 100

What is the most effective nutritional tool to prevent milk fever? A. Use of Ca pastes and gels B. Use of anionic salts and/or minimise Ca and K amount in the ration C. Inject calciotropic hormones

Answer 100

B. Use of anionic salts and/or minimise Ca and K amount in the ration

Question 101

What can probably indicate more, that we have hypocalcaemia in the herd? A. Low milk fat content B. Reduced dry matter intake C. Increased incidences of mastitis and metritis

Answer 101

C. Increased incidences of mastitis and metritis