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BIOLOGY OF TRANSITION & ADAPTIVE
MECHANISMS
José Eduardo P. Santos
Veterinary Medicine Teaching and Research Center
School of Veterinary Medicine
University of California - Davis
Transition Period
• 3 wk before to 3 wk after parturition
• Biggest metabolic and endocrine challenge during the
lactation cycle
– Dramatic increase in nutrient requirements
– Dramatic decrease in DMI
• Period when the cow is most susceptible to metabolic
and infectious problems
Four Major Tasks Must be Achieved During the
Transition Period:
• Adapt the rumen to a high energy diet
– Rumen papillae and microflora
• Minimize the degree of negative EB
• Maintain normocalcemia
• Reduce the degree of immunosuppression around parturition
Mechanisms of Adaptation
by the Cow to Dietary
Changes and the Onset of
Lactation
Average Cross Section Area of Rumen Papillae
Dirksen et al. (1985)
1.3
1.2
1.1
1
0.9
mm2
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
week relative to calving
Low energy
High energy
3
4
5
6
7
8
9
Rumen Papillae Measurements in Transition Dairy
Cows
Day Relative to Calving
-21
-7
10
22
Length, mm
8.3
7.6
6.4
8.6
Width, mm
2.5
2.1
2.2
2.5
17.8
14.2
14
17
Surface area, mm2
Reynolds (1999).
Dietary Energy Concentration, Papillae Surface
Area and Rate of VFA Absorption (Dirksen et al., 1985)
50
45
40
35
30
25
20
15
10
5
0
Low
High
Low
Diet Energy Density
Surface area (mm2)
Absorption rate (mmol/min)
VFA Absorption from the Forestomachs
• Passive diffusion or transcellular transport
• Damage to the epithelium of rumen papillae:
Parakeratosis
– Reduces VFA absorption from the forestomachs
(keratinized epithelium works as a barrier)
• Turnover time of rumen epithelium (Goodlad, 1985)
– Sheep
• high concentrate diet: 10.9 d
Impaired VFA Absorption
• VFA accumulation in the forestomachs
– Propionate reduces smooth muscle motility
• Increases osmolarity and decreases pH of the rumen
fluid
– Decreases DMI
• Reduces energy absorption
Impaired VFA Absorption
• Predisposes the cow to digestive disorders:
– Indigestion
– Displacement of abomasum
– Ruminal acidosis-laminitis
Effect of initiation of lactation on DMI and nutrient requirements
of dairy cows (CPM-Dairy, 1999)
Day Relative to Calving
Item
Multiparous
Primiparous
- 21
+1*
-21
+1**
BW, kg
720
730
610
620
DMI, kg/d
13.2
9.90
9.50
7.71
DMI, % BW
1.84
1.36
1.56
1.24
Energy, Mcal/d
16.8
20.5
15.5
17.7
MP, g/d
880
3,155
884
2,730
Ca, g/d
13.0
43.0
13.0
36.0
Requirements
 * 13 kg of colostrum with 5% fat and 16% CP
 ** 10 kg of colostrum with 5% fat and 16% CP
Metabolic and Endocrine Adaptations
• Dramatic increase
synthesis)
in
nutrient
requirements
(colostrum
• Cow has two mechanisms to compensate:
– Increase DMI
– Redistribute nutrients away from nonmammary tissues
• However, DMI decreases!!
• Endocrine changes:
 bST levels
 ß-adrenergic receptors on adipose tissue
 insulin resistance in the adipose tissue
 insulin concentration in plasma
 glucagon concentration in plasma
Altered ratio insulin:glucagon
activity of HS Lipase
 IGF-1 concentration in blood
• Parturition:
 cortisol
 estrogens
 progesterone
Such changes increase hepatic gluconeogenesis and
increase lipid mobilization from the adipose tissue
Adaptation to supply precursors for lactose, fat and protein
synthesis in milk
• Changes in the ratio lipolysis:lipogenesis
• Increased liver output of glucose
• Decrease in the ratio glycogen:TG in the liver
• Increased protein synthetic activity of the liver
• Higher plasma levels of:
– NEFA
– BHBA
– Glucose
• Decreased plasma Ca and P
• Decreased plasma retinol (38%), a-tocopherol (47%), and
ß-carotene (30%)
• Impaired leukocyte function:
– Neutrophils exhibit impaired ability to ingest and kill
bacteria
– Lymphocytes exhibit depressed blastogenic activity
• Results in lower antibody production
Estimated Energy Required by Prepartum Holstein Cows
2.5
NEL, Mcal/kg
2.25
2
1.75
1.5
1.25
1
-25
-20
-15
-10
Day relative to calving
Mature
Young
-5
0
g/d
Supply and Demands of Glucose for Transition
Cows Fed for Ad Libitum Intake
2500
2250
2000
1750
1500
1250
1000
750
500
250
0
-21
-17
Adapted from Overton (1998)
-13
-9
Supply
-5
-1
3
Requirements
7
11
15
19
Decrease in Whole Body Glucose Oxidation in
Cows During the Transition Period (Bennink et al., 1972)
DIM
Glucose
entry, g/d
Glucose
oxidized, g/d
Glucose
oxidized, %
-30
1480
522
35.3
-7
1600
504
31.5
+10
2000
166
8.3
+40
2560
282
11.0
Conversion of Propionate and Alanine to Glucose
During the Transition Period (Overton et al., 1998)
4
umol/h * g wet weight
3.5
3
2.5
2
1.5
1
0.5
0
-21
1
Propionate
21
Alanine
65
Lipid Accumulation in the Liver
Adipose tissue
LIVER
NEFA
Other tissues
- Oxidized
- Ketogenesis
- Reesterified to TAG
VLDL
Disposal of FA by the Bovine Liver
• Oxidation of TAG by hepatic cells:
– Limited by the lack of high hepatic lipase activity in
ruminants
– Limited by the lack of precursors for oxidation of
Acetyl CoA
– Limited by the lack of Carnithine to transport FA from
the cytosol to the mitochondria of the cell
Disposal of FA by the Bovine Liver
• TAG secretion
– Limited by the low secretion of VLDL
• Limited TAG hydrolysis
• Transfer of FFA from the cytosol of the cell to the
SER
• Activity of Microssomal Transfer Protein (TAG to
the site of VLDL packaging)
• Apo B synthesis and incorporation into VLDL
• Ketogenesis
Predicted DMI (% BW) of Prepartum Holstein Cows
Grummer (1998)
2.2
2
1.8
1.6
1.4
1.2
1
-21
-18
-15
-12
Mature
-9
Young
-6
-3
0
Effect of Prepartum DMI on Energy Metabolism of Transition Cows
Control
Force-Fed
D -2
D1
D 28
D –2
D1
D 28
Glucose, mg/dl
63.4
60.3
56.7
76.5**
59.0
50.1
BHBA, mg/dl
11.9
17.6
17.1
12.5
18.1
18.2
NEFA, mEq/l
0.876
0.992
0.395
0.641
1.064
0.534
Total lipid, %
30.7*
30.6
---
23.5
35.1
TG, %
Glycogen, %
23.2**
2.5
26.9
3.6
-----
12.4
4.2
25.3
2.7
Hepatic (DM basis)
Bertics et al. (1992)
Performance of primiparous when grouped separately from
multiparous cows
Item
Multipar. + Primip.
Primiparous Only
Eating time, min/d
184
205
Eating bouts / d
5.9
6.4
Concentrate intake, kg/d
10.1
11.6
Silage intake, kg/d
7.7
8.6
Lying time, min/d
424
461
Resting periods/d
5.3
6.3
Milk yield, kg/130d
2,383
2,590
Milk fat, %
3.92
3.97
Adapted from Grant and Albright (1997)
Fractional Protein Synthetic Rate in The Liver of Holstein
Cows (Bell, 1995)
Hepatic protein synthesis (%/d)
40
30
20
10
0
-47
-9
6
Day relative to calving
44
Why Transition Cows are More Susceptible
to Metabolic Disorders and Become Sick?
Adaptation Failures
• Digestive problems happen because the rumen
epithelium and its microflora are not adapted to
the new diet
– Indigestion, rumen
abomasum, laminitis
acidosis,
displacement
of
• Problems related to mineral metabolism happen because the
endocrine system is capable of setting homeorrhetic controls
to overcome the high demand for minerals
– Hypocalcemia
• Immunosuppression: Decrease in plasma concentration of
vitamins and minerals with antioxidant properties, energy
and protein deficiency, endocrine challenges, and
hypocalcemia
– Retained placenta, mastitis, and secondary problems such
as ketosis, LDA, and laminitis
Immunosuppression
• Progesterone drop (not a factor)
• Estrogen rise (may play a role)
• Cortisol rise (contributes, but too late)
• Milk Production??
– Mastectomy study from Iowa
Nutritional Strategies to Prevent Metabolic
Disorders During Transition
• Energy is the most important factor
– Formulate diets with high fermentable energy content
• This supplies energy as VFA and amino acids in the
form of microbial protein
• Adapts the rumen epithelium and its microflora to
periods of high intakes of high energy diets
– Avoid drastic changes in diet energy content ( 10%)
Manage BCS at the End of Lactation
• Difficult in one-group TMR herds
• Reproductive efficiency is a key factor to avoid a large
number of obese cows in the herd
• Avoid any loss of BCS during the dry period
– Weight loss will predispose cows to ketosis and
subsequent problems
Effect of BCS at Calving on LDA Incidence
1401 cows in 95 Michigan dairy herds (Dyk et al., 1995)
9
8
Prepartum DMI, % BW
7
6
5
4
* BCS
<3
> 3 to 4
>4
1.76
1.76
1.65
3
2
1
0
< 3.25
3.25 - 4.0
LDA Incidence, %
> 4.0
• Adjust fiber level and forage source for the target group
– Corn silage: high in fermentable energy, low in Na and K
– Add some high quality long hay to the TMR to provide
adequate physically effective NDF (23%)
• Increases rumen fill, stimulates rumination and helps
prevent digestive problems
• Adjust CP for primiparous cows
– Multiparous cows: more prone to TAG infiltration in the
liver  Reduces ureagenesis
– No evidence that feeding prepartum a high protein diet to
mature cows is beneficial to lactation performance
– Caution with high prepartum protein diets to Multiparous
• Use acidogenic salts whenever necessary for multiparous
cows, but avoid it in prepartum heifer diets
– Potential for reducing DMI
– Data from laboratory animals suggest that a slight
metabolic acidosis may:
• compromise hepatic gluconeogenesis
• reduce amino acid
gluconeogenesis
uptake
by
the
liver
for
– Data from dairy cows: reduced insulin secretion and
impaired hepatic uptake of NEFA
• Boost trace mineral and vitamin content of prepartum diets
– Zn, CU, Se, Vit. E and Vit. A
– This might partially
immunosuppression
minimize
the
degree
of
– Reduces incidence of new IMI
• Use gluconeogenic precursors when necessary
– Insulin response: inhibits HSL, which decreases the flux
of NEFA from the adipose tissue and reduces
ketogenesis