Nutritional Management of the Calving and Lactating Cow Flashcards Preview

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Flashcards in Nutritional Management of the Calving and Lactating Cow Deck (19)
1

What are the risks of having a low body condition score (BCS) at calving in dairy herds?

• Decreased dominant follicle diameter

• Reduced insulin and IGF-1

• Low LH pulse frequency

• Poor Fertility!

• Plus increased risk of :

• Retained placenta

• anoestrous

• metritis

• Lameness

• All of which contribute to further reductions in conception rate and increased days open (not in calf)

2

What are the risks of having a high BCS at calving in dairy herds?

•Increased risk of:

• Metritis • Ketosis

• Milk fever

• Cystic ovaries

•All of which are likely to reduce conception rate and increase days open

• Poor fertility!

3

What is the recommended BCS for calving?

Avoid more than .... loss from partition to insemination

 

Calve in BCS 3 (on a scale of 1 to 5)

• 5 on a scale of 1 to 9

• Midrange

Avoid more than 0.5BCS loss from parturition to insemination/joining

- Quality & quantity of DMI

4

High ..... can reduce progesterone [ ] and can lead to embryo loss

High DMI/energy

5

High ..... and high .... in diet around insemination reduces chances of conseption

high protein and high energy

6

How do we calculate the mineral requirement for a lactating cow?

  • Requirements calculated in similar way to energy and protein i.e. replace endogenous losses (faeces, urine skin)
  • Using factorial methods and balance studies 
  •  Recommended feeding values
  • Requirements are usually in gross amounts
  • Need to consider availability in feed

7

Ca and P in regards to lactation?

  • Net req. for lactation is amount deposited in milk
    -milk quality
  • High at peak lactation
    -may be difficult to obtain all from diet
  • Absorption highly variable
  • Ratio important
    - MORE CA THAN P

8

Where does most Ca loss occur?
How can we combat these losses through nutrition?

• Renal losses small, but can be elevated with anionic feeds

Negatively charged feeds (salts)

• DCAD (Dietary Cation Anion Difference)

Prevent hypocalcaemia during transition

Most lost through faeces, colostrum and milk

• PTH and 1,25-dihydroxycholecalciferol (calcitriol or 1,25- dihydroxyvitamin D3 ) and calcitonin key hormones

9

What is the process of hyPOcalcaemia (low)?

• PTH synthesised by parathyroid gland

• Stimulates Ca resorption from bone

• PTH stimulates calcitriol synthesis in kidneys from precursor (25 hydroxyvitamin D3 )

• Stimulates Ca transport proteins in gut to absorb more Ca, also stimulates Ca resorption

• Requires vitamin D from diet or synthesis from cholesterol in skin on UV exposure

10

What is the process of hyPERcalcaemia (high)?

Calcitonin released from thyroid gland to promote bone mineralisation and reduce renal Ca reabsorption (increasing Ca excretion)

11

What are the direct economic costs of milk fever?

• Treatment cost and reduced milk yield

• 4-28% of cows relapse and may become ‘downer’ cows (20-67% of these die)

12

What are the indirect economic costs of milk fever?

• Dystocia

• poor appetite

• uterine prolapse

• retained placenta

• Metritis (inflammation of uterine wall)

• displaced abomasum

• greater risk of developing ketosis and mastitis

• All related to reduced muscle function

• Low [Ca] also reduces insulin production

13

What are the dietary options for reducing milk fever?

Ca and vitamin D

• Manipulating dietary cation-anion difference (DCAD) by feeding anionic salts

• Mobilise Ca from bones during transition

• Replenishing Ca reserves

14

What are the non-diet risk factors associated with milk fever?

•Breed

- Channel Island breeds most susceptible

- Reduced concentration of intestinal receptors for calcitriol

• Climate
- Incidence increases with evaporation rate

- Greatest in cold, wet weather when big difference between max and min temperatures
- Related to DMI and stress-induced adreno-cortical hyperactivity
- Ca and Mg metabolism alter in cold-stressed sheep

- Greater Ca excretion and lower plasma [Mg]

15

How can we manage milk fever?
-think age, BCS, genetics

  • Management
  • Greater in older cows
    - Reduced ability to mobilise bone Ca, reduced calcitriol production, reduced number of intestinal Ca receptors (ie less Ca absorbed)
  • Greater if BCS >3.5 and <2.5
    - Reduced DMI
    - Greater tissue catabolism
    - Increased milk protein (and therefore Ca secretion) 
  • Greater in assisted cows
  • Less in induced cows and twin-bearers
    - More favourable physiological status
  • Genetics
    - More likely if already had Milk Fever
    - h2 estimates 0.09-0.13

16

Response to energy supplements

1. efficiency of ME use for milk

How do acetate levels affect this?

  • Too low
    - Insufficient short to medium chain fatty acids synthesised required for milk synthesis
  • Too high
    - Insufficient propionate for gluconeogenesis

17

Response to energy supplements

2. Diet Substitution 

 

  • Predicted increase in milk yield often not achieved due to substitution
  • Substituting forage for supplement vis. vis. 
  • Greater for high quality forages
  • Greater at higher concentrate intake
  • Adjust stocking rate accordingly

18

Response to energy supplements

3. Milk yield and liveweight 

  • Energy above maintenance partitioned between milk and liveweight gain/reduction in liveweight loss
  • Varies between genotypes
  • Proportion diverted to milk tends to decrease with increased energy intake
  • Affected by rumen VFA proportions
    Increase acetate = more milk
    - Increase propionate = more LWG
  • Stage of lactation
  • Milk yield response greatest in early lactation

19

response to energy supplements

4. Milk components

• Increasing concentrates tend to suppress milk fat levels

• Insufficient acetic acid

• 22-24% ADF (32-36% NDF) commonly recommended