Dairy Transition Period

Question 1

Transition

Dairy Cattle

Answer 1

Changing from dry cow to milking cow
21 d before to 21 d after calving

Demands:
- energy req 🡢 2x
- protein req 🡩 90%
- Ca req 🡢 2x
- Mg req 🡩 50%
- MG produces 900 g/d lactose 🡢 huge 🡩 in liver gluconeogenesis

Goo transition:
- moderate weight loss (~80-100 lbs)
- high milk production

Poor transition:
- significant weight loss (150 lbs+)
- poor milk production
- illness

Question 2

Lypolitic State Peripartum

Answer 2

• 🡩 catecholamine 🡢 hormone sensitive lipase
• 🡣 insuline sensitivy 🡢 starts ~ 3wks prior to calving, lowest at ~4d postpartum
• mobilization of FA late gestation = lipolysis 🡢 🡩 [NEFA]plasma 🡢🡩 NEFA uptake by liver
• normal process, up to a point

Question 3

Fate of Fats Pre-Partum

Answer 3

• oxidized, stored or exported
• storage in liver 🡢 hepatic lipidosis
• some TG storage is normal
• excessive TG impairs liver function

Question 4

Consequences of Fatty Liver

Answer 4

• low DM immeidately after calving
• low milk production
• 🡣 gluconeogenesis

impaired immune function
- 🡣 neutrophil function
- 🡣 antibody prod. B lymphocytes
- 🡣 detox of endotoxin 🡢 🡩 risk of exdotoxemia to mastisis/metritis

Question 5

Post-Partum Lipolysis

Answer 5

• 🡩 energy demands for lactation
• low DMI 🡢 NEG
• 🡩 GH + 🡣 insulin
• rapid mobilization of fat from adipose 🡢 support milk prod.
• normal process, up to a point

Question 6

Fate + Consequences of Ketones

Answer 6

• used by all tissues for energy
• problem 🡢 comsumption < generation
• outcome 🡢 ketones accumulate
  **
  Ketosis **
  1) subclinical 🡢 [BHB]plasma 1400-3000 umol/L
• LDA 7x more likely
• metritis 3x more likely
• 🡣 milk 2-3 kg/d

2) clinical 🡢 [BHB]plasma > 3000 umol/L
- 🡣🡣 DMI
- 🡣🡣 milk prod.
- require med tx

Question 7

Preventing Ketosis + Fatty Liver

Answer 7

• don’t over-feed dry cows
• limit energy to maintenance needs

Question 8

Rationale for energy restriction

Answer 8

• avoid well-fed state
• 🡩 energy 🡢 🡩 acetyl-CoA carboxylase 🡢 🡩 malonyl-CoA 🡢 🡩 esterfication FA 🡢 TG
• malonyl-CoA inhibits CPT-1 🡢 🡣 FA oxidation

ample energy 🡢 🡩 fat deposition, 🡣 FA oxidation
restricted energy 🡢 turnover FA from adipose + 🡩 FA oxidation

Question 9

Implementation

Answer 9

energy req. very low 🡢 easy to overfeed energy
feed low quality forage (straw) 🡢 preferred
limit quantity feed delivered

Question 10

Other diet consideration

dairy cattle

Answer 10

Choline 🡢 improve export of liver TG via VLDL
- 15g/day, rumen protected product

Chromium 🡢 reduce insulin resistance
- 0.12 mg/d
- IC insulin signaling 🡢 reduced resistance
- 🡣 [NEFA] serum pre-partum

Question 11

Non-dietary issues

dairy cattle

Answer 11

minimize stress
- stress 🡩 catecholamines 🡢 🡩 lipolysis

Stressors:
- overcrowding
- poorly designed stall 🡢 🡣 resting time
- heifers housed with older cows
- heat

Question 12

Ca Requirements + Dysregulation

Dairy Cattle

Answer 12

Maintenance 🡢 mature cow ~ 20 g/d
growth
fetal growth late gestation

lactation
- colostrum 🡢 2.1 g/kg
- milk 🡢 1.2 g/kg
- daily req. for Ca 2x w/ onset lactation

Dysregulation 🡢 post-partum cow not ready 🡢 hypocalcemia
- kidney 🡢 fast, limited capacity
- bone 🡢 slow, moderate capacity
- GI 🡢 slow, large capacity

Question 13

Subclinical Hypocalcemia

Answer 13

[Ca]serum < 7.5 mg/dl

🡩 risk of disease:
- RP
- LDA
- Dystocia
- uterine prolapse
- immunosuppression
- ketosis (reduced DMI)

Question 14

Milk Fever

Answer 14

[Ca]serum < 5mg/dl
- muscle fasiculation
- weakness
- ataxia
- recumbency
- cold extremities

Question 15

Controlling Ca2+ at calving

Answer 15

• manipulate DCAD
• limit Ca in diet
• extra Vit. D

Question 16

DCAD

Answer 16

excess of anions 🡢 metabolic acidosis
- (Na + K) - (Cl + S)
- 🡩 urinary excretion of Ca2+
- 🡩 PTH receptor binding

Feeding extra Cl- easiest
- soychlor (soybean meal + HCl)
- biochlor (Cl + S) 🡢 byproduct of MSG manufacture

Feed anionic salts last 2-3 wks of dry period
monitor urine pH
can 🡣 DMI

Question 17

Low Ca Diet

Dairy Cattle

Answer 17

• need < 20 g/d to work 🡢 difficult to achieve

calcium binding agents
- Zeolite 🡢 sodium aluminum silicate
- phytic acid 🡢 rumen protected rice bran

Question 18

Vitamin D

Answer 18

• toxic at very high doses
• feeding ~4-5x normal amounts in combo with negative DCAD diet can improve calcium homeostasis

Question 19

Transition Cow Diseases

Answer 19

• LDA
• RP / metritis
• Milk fever
• ketosis/fatty liver

all secondary to energy + Ca homeostasis in dry period + early lactation